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Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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MEETING ABSTRACTS
Open Access
Parasite infections of domestic animals in the
Nordic countries – emerging threats and
challenges. Proceedings of the 22nd Symposium
of the Nordic Committee for Veterinary Scientific
Cooperation (NKVet)
Helsinki, Finland. 7-9 September 2008
Published: 13 October 2010
These abstracts are available online at http://www.actavetscand.com/supplements/52/S1
S1
Climate change, parasites and shifting boundaries
Lydden Polley1*, Eric Hoberg2, Susan Kutz3
1
Department of Veterinary Microbiology, Western College of Veterinary
Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4,
Canada; 2National Parasite Collection, Agricultural Research Service, United
States Department of Agriculture, Beltsville, Maryland 20705, USA;
3
Department of Ecosystem and Public Health, Faculty of Veterinary Medicine,
University of Calgary, Calgary, Alberta T2N 4N1, Canada
E-mail: [email protected]
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S1
Background: Around the world the three major components of climate
change already evident and escalating in magnitude and significance are;
1) warming; 2) altered patterns of precipitation; and 3) an increased
incidence of extreme climatic events [1]. For the structure and function of
ecosystems, impacts of climate change vary with place and with time,
and among the key outcomes are shifting boundaries for many
components and processes within the systems. Among these
components are pathogens and infectious diseases, including those
caused by helminth, arthropod and protozoan parasites in people,
domestic animals, and wildlife [2].
For host-parasite assemblages, boundaries potentially vulnerable to
climate change include those for spatial and temporal distributions of
hosts and parasites, for parasite survival and development in hosts and in
the environment, for risks of transmission to hosts at critical points in
parasite webs, and for health effects on hosts, including the emergence
or resurgence of disease. The often complex and obscure linkages and
inter-relationships among components of an ecosystem, coupled with the
uncertain and variable trajectories for climate change, make it difficult to
identify all these vulnerabilities, particularly in the medium to long term.
Also, faced with non-overwhelming “stress” most ecosystems display a
degree of resilience that may mitigate some of the consequences of
climate change [3,4], and in some circumstances the significance of
parasites remains essentially unchanged. Finally, some recent shifts in
disease occurrence that intuition might suggest are associated with
climate change have proved likely to be wholly or partly the result of
other factors [5,6].
The primary aim of this paper is to provide a framework for thinking
about the critical potential connections between climate change,
parasites, people, and wildlife in the circumpolar North, and between
these host groups, climate change, parasites and domestic animals in
other areas of the world.
Approaches: Much of the information currently available on climate
change and infectious disease relates to people and is based on
retrospective analyses of associations between components of climate
involved in climate change and the occurrence of disease in human
populations [7,8]. In other instances, features of parasite ecology have been
linked to model-based scenarios for future climate change to generate
medium to long-term projections for parasite and disease distribution and
occurrence [9,10]. Underlying these approaches are observational and
experimental studies in a range of systems exploring, on a more intimate
scale, the relationships between climate and parasite, and sometimes host,
ecology [11-13]. All these lines of enquiry are increasing understanding of
the mechanisms generating boundary shifts for parasites and diseases
resulting from climate change, and are assisting proper targeting of
measures to minimize their impacts on human and animal health.
Encouragingly, effective climate-based forecasting, developed decades ago
for ruminant fascioliasis [14], is now a reality for some epidemic human
malaria in Africa [15] and is being evaluated for other human parasitic
diseases, for example human fascioliasis [16] and leishmaniasis [17] in South
America. Exploration of the effects of climate change on infectious disease
ecology presents many opportunities for valuable comparisons across
pathogen and host groups, and across ecosystems.
Central to understanding these climate change-host-parasite linkages is
the ability to detect and measure shifts in key features of parasites and
hosts and to assemble data unequivocally establishing or refuting links to
climate change. Given relevant meteorological data, although monitoring
and surveillance of parasitic infections and diseases may be possible to
some extent in people and domestic animals, even in remote areas with
limited infrastructure, it is usually more difficult in wildlife [18]. A
particular issue for this host group, especially in Arctic and the North and
other relatively isolated areas, is the currently limited understanding of
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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the parasite fauna, including species diversity and distribution, and its
health significance, especially in the absence of obvious disease or
mortality [19,20]. A recently initiated and very promising approach in
northern Canada and elsewhere is to recruit, train and fund northerners,
particularly harvesters who have frequent contact with wildlife, as health
monitors. This program is greatly enhanced in the longer term where
wildlife and wildlife health are introduced into curricula for schools in
northern communities (see http://www.ccwhc.ca/Sahtu/index.php).
The fragile North: The North is among areas of the world where climate
change is already having significant and obvious effects and is impacting
northerners and the animal and plant resources vital to their health and
well-being [21,22]. For example, at risk on land are keystone wildlife
species, including caribou, reindeer, moose, thinhorn sheep and muskoxen,
waterfowl, and fish, together with berries and other foods of plant origin.
In the surrounding oceans, polar bears, seals, walrus, seabirds and fish are
all vulnerable. Among the elements of climate change threatening the
health and sustainability of people and wildlife in the North, perhaps the
most significant is warming, which is shifting boundaries for animals and
plants [23], and for sea ice, permafrost, snow cover, and hydrology, as well
as local and regional infrastructure [22]. Warming is also a cause of rising
sea levels and the consequent erosion and flooding of coastal areas and
disruption of coastal ecosystems and settlements [22].
People and animals that inhabit the North are beset by an array of helminth,
arthropod and protozoan parasites. Most of these are restricted to one of
the two host groups, but several – the zoonoses – are transmissible
from animals to people, often through foods integral to traditional local
cultures [18]. These zoonoses include (in North America) Trichinella,
Anisakis, Diphyllobothrium, Echinococcus, and Toxoplasma, and perhaps
Cryptosporidium and Giardia. All of these can cause obvious clinical disease
in people, but not in everyone who is infected.
Host and parasite vulnerabilities: Many aspects of host and parasite
ecology in the North and elsewhere have been identified as potentially
vulnerable to climate change. Among possible consequences are boundary
shifts that can alter the structure and function of host-parasite
assemblages [24,25]. The speed and extent of these shifts vary with place
and with time. For example, those linked to extreme climatic events may
be rapid and localized, whereas those resulting from warming may be
more gradual and widespread. For definitive and intermediate hosts,
including arthropod vectors, these shifts include: 1) geographic
distributions – expansion into new areas and/or loss from old areas and, in
some cases, local to regional extinctions, together with shifts in migration
routes; 2) faunal structure – qualitative changes in the composition of
multi-species host communities, including shifts in opportunities for
contacts between wildlife and domestic animals; 3) trophic linkages including predator-prey relationships important for parasite transmission,
especially for several zoonoses [26]; 4) phenology - especially the timing of
breeding seasons and migrations, and the synchronization of the need for
and availability of food; 5) level of nutrition – determined by the
composition, availability, accessibility and quality of food and water; 6)
health and wellbeing – including patterns of disease occurrence, and
possible detrimental synergies between parasites, other infectious agents
and other diseases; 7) host abundance – possibly affecting host density
and thus parasite transmission dynamics; 8) behavioural patterns –
influencing exposure to parasite and in some cases subsequent
environmental contamination with parasites; and 9) parasite evolution [27]
- likely to be detected first among protozoans. For people dependent to
some extent on wildlife, as many northerners are, parasites may be one of
the means by which climate change results in shifts in the availability and
quality, or perceived quality, of their food and other key products (e.g.
hides and pelts) of wildlife origin, and in the role of wildlife in their cultural
and economic wellbeing and in the sustainability of northern communities.
For parasites, some potential boundary shifts are similar to those for hosts.
For example, as distributions and faunal structures for hosts shift, so too will
those for parasites. In some ecosystems, as a result of host switching, both
immigrant (or invasive) and endemic hosts may experience new parasites,
and these may be especially pathogenic for naïve hosts and may result in
emergent or resurgent diseases. Shifts in parasite faunal structure may also
result from altered trophic linkages, and the levels of nutrition, health and
wellbeing of hosts will influence their susceptibility to parasites and other
diseases and may lead to shifts in the role of parasites in ecosystem
dynamics. Outside their mammalian and avian hosts, many parasites have
life cycle stages in the environment or in ectothermic intermediate hosts
Page 2 of 31
and vectors that are exposed directly to climate. Key potential boundary
shifts here are in parasite survival and development rates [12] and, for some
species, in amplification rates for parasites developing in ectothermic hosts
[11]. If warming from climate change enhances these rates, lengthens the
summers vital for the transmission of many northern parasites, and shortens
and softens the winters then, simplistically, more infective stages of
parasites could be available sooner and the transmission period could be
extended. In some instances, these shifts have the potential to generate
greater parasite abundance in the definitive hosts and to increase their
health impacts.
Some case studies: Despite our currently relatively limited understanding of the ecology of host-parasite assemblages in the Arctic and
the North, it is possible to speculate how some might be influenced by
climate change. Although evidence transforming this speculation to
certainty remains sparse, it is important to consider these issues and
especially to identify potential high-risk scenarios for the emergence of
significant parasitic disease in people and in wildlife.
Trichostrongyles of Ungulates: Trichostrongyles (e.g. Ostertagia
gruehneri and Teladorsagia boreoarcticus) are non-zoonotic nematodes
that as adults parasitise the abomasum or intestines. They have direct life
cycles involving the development of eggs deposited in the feces to freeliving, infective larvae in the environment. Infection of ungulate hosts is
by ingestion of these larvae. Climate change, as well as its positive or
negative effects on the hosts, may shift patterns of development for the
parasites’ free-living stages. For example, assuming adequate moisture,
longer, warmer summers may increase survival and development rates
for the free-living stages leading perhaps to shorter generation times and
to greater abundance and increased longevity for infective larvae in the
environment. This in turn may increase the infection pressure and
parasite loads for hosts and lead to greater adverse impacts on host
health (e.g. weight loss and reduced conception rates) [28,29] and, for
species important as food for northerners, on human health. In addition,
altered summer transmission dynamics and fall climate may shift patterns
of larval inhibition in the gastro-intestinal mucosa, an important
mechanism for overwinter survival by some trichostrongyles in other
areas of the world. A useful preliminary glimpse of the links between
climate change and altered ecology for trichostrongyles can be derived
from basic information about pre-patent periods and the relationships
between environmental temperatures and larval survival and
development rates as determined in the laboratory and in the field. Data
are plentiful on these aspects of trichostrongyles of domestic animals in
several areas of the world [12], but caution is required when attempting
to extrapolate these data to the species of parasites infecting freeranging hosts, particularly in the Arctic and the North.
Protostrongylids of Ungulates: Protostrongylid nematodes (e.g.
Umingmakstrongylus pallikuukensis, Parelaphostrongylus odocoiei and
P. andersoni) are non-zoonotic and live as adults in the airways, lung
parenchyma or skeletal musculature. Their life cycles are indirect, involving
development of first-stage larvae deposited in feces to infective larvae in
gastropod intermediate hosts. Infection of ungulates is by ingestion of infected
gastropods or of infective larvae spontaneously emerged from the gastropods.
The life cycle stages of these parasites outside the hosts have
vulnerabilities to climate change generally similar to those of the
trichostrongyles but it is possible that gastropod mobility and avoidance
of extreme habitat conditions may protect the larvae from some of the
effects of a changed climate [30].
For U. pallikuukensis, an empirical model derived from laboratory and field
studies demonstrated that warming in the North probably has already
shortened larval development times in gastropods and shifted
transmission dynamics from a two-year to a one-year adult-to-adult cycle
[31]. A similar model for P. odocoilei indicated that temperature
constraints affecting larval development rates in gastropods may define
the northern limits of the parasite’s distribution, and that warming may
remove these and lead to an expanded parasite distribution [10]. Also, for
U. pallikuukensis, attempted experimental infections indicated that
thinhorn sheep, potentially newly sympatric with muskoxen as a result of
shifts in host geographic distributions perhaps associated with climate
change, are not susceptible to the parasite [32].
Trichinella nativa Trichinella is a genus of zoonotic nematode containing
species that infect a range of vertebrates, including people, in many parts
of the world. Trichinella nativa is the primary northern species. Adult
Trichinella live in the small intestine, and the larvae produced by the
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female parasites migrate to skeletal muscle and sometimes other tissues.
These larvae are the parasite’s infective stage and transmission is by
carnivorism, including feeding on carrion. In the North many host species
are infected, and of special concern are those consumed by people,
especially polar and black bear, walrus, and seal. Other than in carrion,
life cycle stages of Trichinella are not exposed to the environment and
any effects of climate change are likely to result primarily from shifts in
host faunal structure and trophic linkages [26]. Outside the North, the
ecology of Trichinella may be modified by climate-induced shifts in
contacts between wildlife and domestic animals, and perhaps through
behavioural shifts in the utilization of infected hosts as food for people.
Cryptosporidium and Giardia: Among the several species and genotypes
currently established for each of these two genera of protozoans some are
zoonotic and infect a range of hosts but most seem restricted to a single
host species [33]. Although some species/genotypes are shared between
people and domestic animals, the significance of wildlife as sources of
human infections, and of people as a source of the parasites for wildlife,
remain uncertain and unexplored. Both parasites live primarily in the small
intestine and the life cycles are direct. Infection is by ingestion of infective
oocysts (Cryptosporidium) or cysts (Giardia) from the environment or from
contaminated food or water. Climate change has the potential to alter
survival rates for the cysts and oocysts (which are infective when voided by
the hosts) and, because both parasites are found in surface water, shifts in
local and regional hydrology may alter parasite distributions and the risks of
human and animal exposure. In human settlements altered patterns of
precipitation and extreme climatic events may disrupt the integrity of the
infrastructure, particularly water supplies and sewage disposal, increasing
the risk of human infection. In addition, these elements of the climate
change may result in increased run-off and contamination of water with
animal feces, and increased risk of zoonotic transmission.
Priorities for action: For people, domestic animals and especially
wildlife, in many situations around the world it is difficult to identify all
the causes of detectable shifts in disease occurrence and, correctly,
efforts are directed principally at mitigation of the disease and at
effective control. Additionally, for all host groups, it may be difficult to
tease parasites from among other potential contributors to disease, and
to determine the role of climate in shifts in disease ecology and host
health [34]. For wildlife, the detection of these shifts may also be
hampered by a lack of baseline data for the occurrence and significance
of pathogens and diseases. In exploring climate change as a cause of
new patterns of disease, however, much can be learned from the many
data-derived relationships between key climatic factors and host, parasite
and disease ecology, and the integration of these with projections for
climate change trajectories. This capability, coupled with an integrative,
multidisciplinary and ecological approach, makes possible the
identification of parasitic infections and diseases likely to be particularly
susceptible to climate change and, with adjustments for regional
variations, the exploration of some of the possible consequences of
accelerating climate change for the occurrence of these diseases and for
animal and human health. This is a very urgent need, and without such
an attempt to anticipate the possible, society is likely to be a more or
less impotent spectator to the certainty of continual ecological calamities.
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S2
GIS in vector borne diseases
Guy Hendrickx
Avia-GIS, Risschotlei 33, B-2980 Zoersel, Belgium
E-mail: [email protected]
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S2
Introduction: Since its origin in the late 1980’s, the development of
geographical information science and of geographical information
systems (GIS), the toolset enabling to conduct this type of research, has
now reached the necessary maturity to be considered a main stream
application: GIS evolved from the status of ‘a promising tool’ to the status
of ‘a tool achieving its promises’. To maintain this status the entire chain
of events from data collection to data analysis must be adapted to the
specific needs and requirements of spatial analysis.
From spatial data sampling to spatial information systems: Avia-GIS
is a consulting company specialized in the development of agroveterinary and public health information systems. In Figure 1 below the
developed approach enabling the integration of the different steps
required for the development of data driven spatial information systems
is depicted. In this paper a selection of obtained results are shown when
applying this approach to the field of vector borne diseases.
First the principal of statistical spatial distribution models is highlighted
using the example of Rhipicephalus appendiculatus in Kenya, a tick
transmitting East Coast fever in cattle. The need for representative ground
data obtained using a robust spatial sampling strategy is highlighted and
the example of how this was achieved in MODIRISK, a project aiming at
mapping mosquito species and biodiversity patterns in Belgium, is given.
Figure 1 (abstract S2) From spatial data to spatial information systems
Page 4 of 31
Spatial model outputs using observed presence and absence data for
Aedes albopictus, an invasive species in (Southern) Europe, obtained
through an international network of scientific collaborators, are then
compared to potential distribution maps computed using a multicriteria
decision analysis approach (MCDA) based on expert knowledge. The
limits and complementary value of both approaches are discussed.
The impact of wind on the dispersal of airborne vectors of disease is
illustrated using as an example the current invasion of Europe by
bluetongue (BTV8) through endemic midges. Understanding these
dispersal patterns is an important step toward adding a dynamic
component to such models and increase there predictive potential as
part of planning tools for control measures: e.g. protection of cattle
trough focussed vaccination. Ongoing work on the development of an
airborne trapping device will further improve our knowledge of the 3D
distribution patterns/ behaviour of the airborne midges and therefore the
quality of the developed models.
Finally the example of Vet-geoTools is used to show how an integrated
spatial veterinary information system can contribute to the improved
management of veterinary outbreaks.
Conclusion: It is concluded that the development of such an integrated
approach using state of the art tools is essential to extract maximal value
of geographical information science outputs. This can only be achieved
through combining state of the art research with state of the art tool
development: a perfect meeting place, and play ground, for academic
groups and innovative SME’s.
Further reading: Information on all projects and outputs mentioned
above can be downloaded directly from the Avia-GIS website at: http://
www.avia-gis.com
S3
Vector-borne nematodes, emerging parasites in Finnish cervids
Sauli Laaksonen*, Antti Oksanen
Finnish Food Safety Authority Evira, Fish and Wildlife Health Research Unit,
P.O.Box 517, FI-90101 Oulu, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S3
Summary: There is a growing body of literature documenting the
expansion of emerging parasites to sub-arctic areas. The potential impact
of global warming on shifts in the spatio-temporal distribution and
transmission dynamics of vector-borne diseases in domesticated and wild
ungulates may be remarkable [1]. Recent Finnish studies have revealed
an array of Filarioid nematodes and associated diseases that appear to be
emerging in northern ungulates [2-4].
Members of the genus Setaria (Filarioidea: Onchocercidae) are found in
the abdominal cavities of artiodactyls (especially Bovidae), equids and
hyracoids. All produce microfilariae which are present in host blood [5],
and known vectors are haematophagous mosquitoes (Culicidae spp) and
horn flies (Haematobia spp.) [6].
The Filarioid nematode Setaria tundra was first described in semidomesticated reindeer (Rangifer tarandus tarandus) in Arkhangelsk area,
Russia [7]. Setaria infections appear to have emerged in Scandinavian reindeer
not later than in the 1960’s. In 1973, S. tundra was observed for the first time
in northern Norway where there was an outbreak of peritonitis in reindeer, as
there was in Sweden, too. Also in 1973, tens of thousands of reindeer died in
the northern part of the Finnish reindeer husbandry area. Severe peritonitis
and large numbers of Setaria worms were commonly found. Following this,
the incidence of Setaria in reindeer in Scandinavia diminished.
According to meat inspection data and clinical reports from practising
veterinarians, the latest outbreak of peritonitis in reindeer started in 2003
in the southern and middle part of the Finnish reindeer herding area. In
the province of Oulu, the proportion of reindeer viscerae condemned in
meat inspection due to parasitic lesions increased from 4.9 % in 2001 to
47 % in 2004 and in Lapland from 1.4 % in 2001 to 43 % in 2006. The
focus of the outbreak moved approximately 100 km northwards yearly so
that in 2005 only the reindeer in the northernmost small part of Finland
(Upper Lapland) were free of changes. In the same time the outbreak
seems to have settled in the southern area. [2].
The causative agent was recognized both morphologically and molecular
biologically as S. tundra. DNA sequence of S. tundra parasitising reindeer
in North Finland was deposited in GenBank under accession number
DQ097309. [2,3].
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The habitus of reindeer calves heavily infected with S. tundra expressed
decreased welfare; low body condition and undeveloped winter fur coat.
The meat inspection findings of peritonitic reindeer carcasses included
ascites fluid, green fibrin deposits, adhesions and live and dead S. tundra
nematodes. Histopathologically, changes indicated granulomatous
peritonitis with lymphoplasmacytic and eosinophilic infiltration. No
specific bacterial growth was found. No significant impact on meat pH
values nor on organoleptic evaluation of meat was found. There was a
significant positive correlation between worm count and the degree of
peritonitis and a negative correlation between the degree of peritonitis
and back fat layer [2]. Earlier, Setaria yehi has been associated with low
grade chronic peritonitis in Alaskan reindeer [8] and S. tundra with mild
to severe peritonitis together with Corynebacterium sp. in Swedish
reindeer [9]. Our studies revealed that S. tundra can act as a significant
pathogen for reindeer, which was evident at both ante and post-mortem
inspection and in histological examination.
In order to monitor the S. tundra parasite dynamics in nature, parasite
samples from wild cervids has also been collected [2]. In moose (Alces
alces), the most abundant wild cervid in the reindeer herding area, only
few cases of pre adult encapsulated S. tundra nematodes on the surface
of the liver, but no peritonitis, were seen.The moose was evidently not a
suitable host reservoir for the present S. tundra haplotype. The moose
population in northern Finland peaked in the years 2004 and 2005. There
is a previous report of a peritonitis outbreak in moose in Finnish Lapland
in 1989 associated with Setaria sp. nematodes [10]. The parasite was
genetically identified as another haplotype of S. tundra. Although this
earlier outbreak took place within the reindeer husbandry area, no
reports on associated increased morbidity in reindeer exist.
According to our studies it is possible that the high percentage of the
Kainuu population of wild forest reindeer (Rangifer tarandus fennicus) with
signs of peritonitis caused by S. tundra (62 % of 34 animals examined) [2]
is associated with the decrease of the population [11] from 1700
individuals in 2001 to 1000 in 2005.
Two roe deer (Capreolus capreolus) examined fresh in the field had
S. tundra nematodes in abdomen but no signs of peritonitis. According to
our studies, the roe deer seems a capable host and asymptomatic carrier
for S. tundra. This conclusion is supported by the first S. tundra
appearance in Scandinavia in the early 1970’s [2] simultaneously with the
invasion of the roe deer to North Scandinavia [12]. Further, there were
minor nucleotide differences between the reindeer S. tundra sequence
(648 bp) and that from roe deer parasites in Italy (GenBank AJ544874)
[13]. In the consideration of reservoir host capacity of roe deer it is worth
noting that especially young male roe deer can migrate hundreds of
kilometres from their birthplace [14].
Our studies have revealed that S. tundra can have a significant
pathogenic influence on the health of reindeer, and cause outbreaks also
in moose population [10] and may further have consequences to cervid
population dynamics.
The S. tundra outbreak in Sweden in 1973 was associated with unusually
warm weather and appearance of larger than usual numbers of
mosquitoes and gnats [9]. The summers 1972 and 1973 were also very
warm in Finland, as were 2002 and 2003 (Finnish Meteorological Institute
data, personal communication S. Nikander 2004). Mosquitoes are
considered vectors for S. tundra, but the life cycle in vectors is poorly
understood
Climate change is predicted to increase insect activity and thus promote
vector-borne Filarioid nematodes’ emerge to North and becoming a
threat to the wellbeing of arctic ungulates. Especially mosquito-borne
diseases are among those diseases most sensitive to climate because
climate change would directly affect disease transmission by shifting the
vector’s geographic range and increasing reproductive and biting rates
and by shortening the pathogen incubation period [15].
Our research group has studied the invasion and reservoirs of S. tundra in
Finnish cervid populations, which studies we shortly review in this paper.
We highlight the possibility that vector borne parasites may, by the
impact of global climate change, further have consequences to wild and
domestic ungulates. The study revealed the absence of baseline
knowledge concerning temporal parasitic biodiversity in cervids at high
latitudes. Therefore it is important to gain knowledge about these
parasites’ ecology, dynamics, and the impact on man and animal health.
Acknowledgements: These studies were partly funded by Ministry of
Agriculture and Forestry (MAKERA).
Page 5 of 31
References
1. Hoberg EP, Polley L, Jenkins EJ, Kutz SJ, Veitch AM, Elkin BT: Integrated
approaches and empirical models for investigation of parasitic diseases
in northern wildlife. Emerg Inf Dis 2008, 14:10-17.
2. Laaksonen S, Kuusela J, Nikander S, Nylund M, Oksanen A: Parasitic
peritonitis outbreak in reindeer (Rangifer tarandus tarandus) in Finland.
Vet Rec 2007, 160:835-841.
3. Nikander S, Laaksonen S, Saari S, Oksanen A: The morphology of the
filarioid nematode Setaria tundra, the cause of peritonitis in reindeer
Rangifer tarandus. J Helminth 2007, 81:49-55.
4. Solismaa M, Laaksonen S, Nylund M, Pitkänen E, Airakorpi R, Oksanen A:
Filarioid nematodes in cattle, sheep and horses in Finland. Acta Vet.
Scand. 2008, 50:20.
5. Anderson RC: The Superfamily Filarioidea. In Nematode parasites of
vertebrates; their development and transmission. 2nd edition. CABI Publishing,
New York; 2000:467-529.
6. Shol VA, Drobischenko NI: Development of Setaria cervi (Rudolphi, 1819)
in Cervus elaphus maral. Helminthologia (Bratislava) 1973, 14:214-246,
(Russian with English abstract).
7. Rajevsky SA: Zwei bisher unbekannten Nematoden (Setarien) von
Rangifer tarandus und von Cervus canadensis asiaticus. Two hitherto
unknown nematodes Setaria species from Rangifer tarandus and from Cervus
canadensis asiaticus Z Infekt Krank. Hyg Haustiere 1928, 35:40-52, (In
German).
8. Dieterich RA, Luick JR: The occurrence of Setaria in reindeer. J Wild Dis
1971, 7:242-245.
9. Rehbinder C, Christensson D, Glatthard V: Parasitic granulomas in reindeer.
A histopathological, parasitological and bacteriological study. Nordisk
veterinaermedicin 1975, 27:499-507.
10. Nygren T: Riistantutkimusosaston tiedote. Bulletin of Finnish Game and
Fisheries Institute 1990, 104, (in Finnish).
11. Kojola I: Petojen vaikutus metsäpeurakannoissa. Suomen Riista 2007,
53:42-48, (in Finnish).
12. Haugerud RE: Rådyret vandrer mot nord. Ottar 1989, 5:31-36, (in
Norwegian).
13. Casiraghi M, Bain O, Guerro R, Martin C, Pocacqua V, Gardner SL,
Franceshi A, Bandi C: Mapping the presence of Wolbachia pipientis on
the phylogeny of filarial nematodes: evidence for symbiont loss during
evolution. International J Parasit 2004, 34:191-203.
14. Cederlund G, Liber O: in Rådjuret, viltet, ekologin och jakten. Almqvist and
Wiksell Tryckeri, Uppsala 1995, 113-117, (in Swedish).
15. Patz JA, Epstein PR, Burke TA, Balbus JM: Global climate change and
emerging infectious diseases. JAMA 1996, 275:217-23.
S4
Human medical view on zoonotic parasites
Antti Lavikainen
Department of Bacteriology and Immunology, Haartman Institute, University
of Helsinki, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S4
Summary: From medical point of view, a zoonosis is any infectious
disease that is naturally transmissible from vertebrate animals to humans
[1]. A stricter definition is a disease that normally exists in other
vertebrate animals, but can be accidentally transmitted to humans [2]. In
Nordic countries, parasites are rare (and zoonotic parasites even more
unusual) causative agents of human infections probably due to good
hygiene and climatic conditions. In most cases, parasitic infections are of
foreign origin, except for some relatively common indigenous infestations
such as enterobiasis (caused by the human pinworm, Enterobius
vermicularis) and pediculosis (caused by the human head louse, Pediculus
humanus).
Worldwide, the most significant genus of human parasites is Plasmodium.
It is the causative agent of malaria, a severe tropical protozoan disease,
which kills globally more than one million people every year [3]. In
Finland, about twenty cases of malaria are diagnosed annually [4]. In
2007, P. knowlesii infection was diagnosed in Finland in a tourist who had
traveled in Malay Peninsula [4]. P. knowlesii is a Plasmodium of monkeys.
This was second reported case of P. knowlesii malaria in a tourist. During
the 19th century, malaria was an indoors transmitted disease in Finland,
as Anopheles mosquitoes hibernated in peoples’ households [5].
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Intestinal parasitoses are the most common parasitic infections. Among
Finnish asymptomatic population, pathogenic intestinal parasites (mostly
Giardia lamblia) can be found from 1.5 % of people [6]. However, only
300 cases of clinical giardiasis are diagnosed in Finland annually [7], and
reported numbers of diagnosed amebiasis cases (caused by Entamoeba
histolytica) range from 30 to more than 100 [7,8]. These protozoans are
human parasites, and infections caused by them can occur through
contaminated food, water or by faecal-oral route. According to the
statistics of the Parasitological unit of HUSLAB (Laboratory of Hospital
District of Helsinki and Uusimaa county, Finland) from 2005 to 2007, the
most important intestinal helminthes were pinworms, the human
whipworm (Trichuris trichiura) and intestinal roundworms (Ascaris spp.).
The swine roundworm (Ascaris suum), is a zoonotic parasite, but it was
not routinely differentiated from human roundworm (A. lumbricoides).
Formerly, the broad fish tapeworm (Diphyllobothrium latum) was a major
health problem in Finland, and it has been called “the national parasite of
Finland” [9,10]. Although it has been diminished drastically, it has not
been totally eradicated. Around twenty human cases are still diagnosed
annually in Finland, and the situation is similar in Sweden [11]. In contrast
to diphyllobothriasis, which is mostly an indigenous disease, human
intestinal taeniases are imported cases. About a handful of taeniasis cases
are diagnosted in HUSLAB yearly, and the beef tapeworm (Taenia
saginata) is more common finding than the pork tapeworm (T. solium). In
the strict sense (see the definition above), diphyllobothriasis and
taeniases should not be called zoonoses, since humans are important
definitive hosts of D. latum and essential for T. saginata and T. solium,
although vertebrate animals (fishes, cattle and swine, respectively) act as
sources of human infections.
Echinococcus spp. are the most important zoonotic cestodes worldwide.
Their larvae are causative agents of serious diseases called
echinococcoses. Until 1960’s, human cystic echinococcosis was a
significant public health problem among reindeer herding Sámi
population in Swedish and Norwegian Lapland [12]. Human cases were
found also in Finnish Lapland, but only few reports have been published.
Later, the parasite was eradicated from the reindeer-dog cycle, and
endemic human cases have not been diagnosed for several decades. In
the Parasitological unit of HUSLAB, eight echinococcosis cases were
diagnosed between 2002 and 2008. These cases cover most of the
diagnoses in Finland during that time period. All of them were caused by
so-called sheep strain of E. granulosus. One of the patients was a Finn,
but an endemic infection was excluded by the strain determination.
Another endemic zoonotic parasitosis, which seems to be disappeared
from Nordic countries as a human infection, is trichinellosis. This disease
caused by larvae of nematodes of the genus Trichinella has not been
diagnosed for a long time. This contrasts the fact that Trichinella spp. are
common in wild and domestic animals [13].
Several exotic parasites, which occur as sporadic companions of travelers,
can cause tissue lesions and even systemic disease. For example,
leishmaniasis is the term given to diseases caused by protozoans of the
genus Leishmania[14]. These parasites are transmitted by sand flies, and
small rodents and dogs are the reservoir of infection. There are two main
types of clinical disease, cutaneous and systemic leishmaniases.
Larvae of gastrointestinal nematodes of dogs and cats (Toxocara canis
and T. cati, respectively), can cause disease called visceral larva migrans in
humans, chiefly in children [15,16]. Larvae migrate through inner organs
and cause mechanical damage and eosinophilic lesions. Toxocara spp. are
geographically widely distributed. Larva migrans is obviously a
underdiagnosed zoonosis, and its prevalence in Nordic countries has not
been studied recently. In HUSLAB material in 2007, seven patients had
positive toxocariasis serology. One of these was most probably an
unspecific seroreactivity because the same sample responded also against
several other helminth antigens. Six patients were children (age of 2-16
years) and one was an elder person (75 years).
Toxoplasmosis is a disease caused by the protozoan parasite, Toxoplasma
gondii which infects up to one-third of the world human population [17].
The definitive host of T. gondii is the cat; humans become infected by
ingesting oocysts (e.g., by eating vegetables contaminated with cat
faeces or soil) or tissue cysts in meat. Toxoplasmosis in neonates and
immunocompromised patients can lead to severe disease and death. It
has been estimated that 50-60 infants suffer from congenital
toxoplasmosis annually (prevalence 1/1000) in Finland [18]. However,
reported prevalences in Sweden, Norway and Denmark are much lower
Page 6 of 31
(0.73-3.1/10,000) [19-21]. Anyway, due to the relatively high prevalence,
indigenous occurrence and severe clinical manifestations toxoplasmosis
can be considered to be one of the most important true zoonotic
parasitoses in the Nordic countries.
In order to understand the transmission dynamics of zoonotic parasitic
infections to humans, it is essential to have knowledge on the life cycle
and prevalence of infection in other animals, both domestic and wild.
References
1. World Health Organization: Zoonoses. [http://www.who.int/topics/zoonoses/
en/].
2. Bannister BA, Begg NT, Gillespie SH: Infectious Disease. Oxford: Blackwell
Science 1996, 392.
3. World Health Organization: Malaria. [http://www.who.int/mediacentre/
factsheets/fs094/en/index.html].
4. Siikamäki H: Malariatapausten määrä pysyi ennallaan. Suomen Lääkärilehti
2008, 63:1847.
5. Huldén L, Huldén L, Heliövaara K: Endemic malaria: an ‘indoor’ disease in
northern Europe. Historical data analysed. Malaria Journal 2005, 4:19.
6. Siikamäki H, Kyrönseppä H, Jokiranta S: Suoliston parasiitti-infektiot.
Duodecim 2002, 118:1235-1247.
7. National Public Health Institute: the Statistical Database of the Infectious
Diseases Register. [http://www3.ktl.fi/].
8. Nohynek H, Siikamäki H, Peltonen R: Matkailijoiden infektiot. Mikrobiologia
ja infektiosairaudet II Helsinki: Kustannus Oy Duodecim: P Huovinen, S Meri,
H Peltola, M Vaara, A Vaheri, V Valtonen , 1 2003, 653-668.
9. B von Bonsdorff: The fish tapeworm, Diphyllobothrium latum; a major
health problem in Finland. World Med J 1964, 11:170-172.
10. Konttinen Y, Hasenson S, Valovirta I, Malmström M, Ikonen E, Virtanen jaI:
Unohdettu kansallisloinen–tapausselostus ja lyhyt kirjallisuuskatsaus.
Duodecim 1997, 113:1549.
11. Dupouy-Camet J, Peduzzi R: Current situation of human diphyllobothriasis
in Europe. Eurosurveill 2004, 9:31-35.
12. Lavikainen A: Ihmisen ekinokokkitauti Suomen, Ruotsin ja Norjan Lapissa.
Suomen Eläinlääkärilehti 2005, 110:7-13.
13. L Oivanen L, Kapel CM, Pozio E, La Rosa G, Mikkonen T, Sukura A:
Associations between Trichinella species and host species in Finland.
J Parasitol. 2002, 88:84-8.
14. Király C: Kasvojen iholeishmanioosi etelänmatkan tuliaisena. Duodecim,
1995, 111:1104.
15. Raether W: Gastrointestinal nematodes in dogs and cats. Parasitology in
focus Berlin: Springer-Verlag: H Mehlhorn 1988, 841.
16. Vuento Risto: Koti- ja lemmikkieläimet tartuntatautien lähteenä. Duodecim
1994, 110:555.
17. Birgisdóttir A, Asbjörnsdottir H, Cook E, Gislason D, Jansson C, Olafsson I,
Gislason T, Jogi R, Thjodleifsson B: Seroprevalence of Toxoplasma gondii
in Sweden, Estonia and Iceland. Scand J Infect Dis 2006, 38:625-631.
18. Lappalainen M: Raskaudenaikaista toksoplasmainfektiota kannattaa
seuloa? Suomen Lääkärilehti 1996, 51:1316.
19. Evengård B, Petersson K, Engman ML, Wiklund S, Ivarsson SA, TeärFahnehjelm K, Forsgren M, Gilbert R, Malm G: Low incidence of
toxoplasma infection during pregnancy and in newborns in Sweden.
Epidemiol Infect 2001, 127:121-127.
20. Schmidt DR, Hogh B, Andersen O, Fuchs J, Fledelius H, Petersen E: The
national neonatal screening programme for congenital toxoplasmosis in
Denmark: results from the initial four years, 1999-2002. Arch Dis Child
2006, 91:661-665.
21. Jenum PA, Stray-Pedersen B, Melby KK, Kapperud G, Whitelaw A, Eskild A,
Eng J: Incidence of Toxoplasma gondii infection in 35,940 pregnant
women in Norway and pregnancy outcome for infected women. J Clin
Microbiol 1998, 36:2900-2906.
S5
Echinococcus spp. and echinococcosis
Bruno Gottstein
Faculty of Medicine, Institute of Parasitology, University of Bern, Bern,
Switzerland
E-mail: [email protected]
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S5
Summary: Echinococcus spp. are cestode parasites commonly known as
small tapeworms of carnivorous animals. Their medical importance lies in
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the infection of humans by the larval stage of the parasites,
predominantly including Echinococcus granulosus, which is the causative
agent of cystic echinococcosis (CE) and Echinococcus multilocularis, which
causes alveolar echinococcosis (AE).
A few other species or genotypes are only very rarely or not at all found
in humans. Due to the emerging situation in many parts of Europe, the
present article will predominantly focus on E. multilocularis .
The natural life cycle of E. multilocularis involves predominantly red and
arctic foxes as definitive hosts, but domestic dogs can also become
infected and represent an important infection source for humans in
highly endemic areas. In the definitive host, egg production starts as
early as 28 days after infection. After egg ingestion by a rodent or a
human, larval maturation will occur practically exclusively within the liver
tissue. The geographic distribution of E. multilocularis is restricted to the
northern hemisphere. In Europe, relatively frequent reports of AE in
humans occur in central and eastern France, Switzerland, Austria and
Germany. Within the past ten years, the endemic area of Europe now
includes many more countries such as Belgium, The Netherlands, Italy,
and most former Eastern countries as far as up to Estonia. The Asian
areas where E. multilocularis occurs include the whole zone from the
White Sea eastward to the Bering Strait, covering large parts of Siberia,
western and central parts of China and northern Japan. Worldwide there
are scant data on the overall prevalence of human AE. Some welldocumented studies demonstrate a generally low prevalence among
affected human populations. The annual mean incidence of new cases in
different areas including Switzerland, France, Germany and Japan has
therefore been reported to vary between 0.1 and 1.2/100,000 inhabitants.
The incidence of human cases correlates with the prevalence in foxes
and the fox population density. Recently, a study documented that a
four-fold increase of the fox population in Switzerland resulted in a
statistically significant increase of the annual incidence of AE cases [1]
(Schweiger et al., 2007). This dramatic increase in red fox populations has
also been reported throughout Europe, especially in urban areas. The
so-called city-fox phenomenon and, thereafter, the increased proximity of
foxes with humans and an urban domestic dog – rodent cycle may,
therefore, have significant public health implications [1-3].
In infected humans the E. multilocularis metacestode (larva) develops
primarily in the liver. Occasionally, secondary lesions form metastases in
the lungs, brain and other organs. The typical lesion appears
macroscopically as a dispersed mass of fibrous tissue with a
conglomerate of scattered vesiculated cavities with diameters ranging
from a few millimeters to centimeters in size. In advanced chronic cases,
a central necrotic cavity containing a viscous fluid may form, and rarely
there is a bacterial superinfection. The lesion often contains focal zones
of calcification, typically within the metacestode tissue. Histologically, the
hepatic lesion is characterized by a conglomerate of small vesicles and
cysts demarcated by a thin PAS-positive laminated layer with or without
an inner germinative layer [4]. Parasite proliferation is usually
accompanied by a granulomatous host reaction, including vigorous
synthesis of fibrous and germinative tissue in the periphery of the
metacestode, but also necrotic changes centrally. In contrast to lesions in
susceptible rodent hosts, lesions from infected human patients rarely
show protoscolex formation within vesicles and cysts. Genetic and
immunologic host factors are responsible for the resistance shown by
some patients in whom there is an early ‘dying out’ or ‘abortion’ of the
metacestode [5,6]. Therefore, not every individual infected with
E. multilocularis is susceptible to unlimited metacestode proliferation and
develops symptoms in the average within 5–15 years after infection. The
host mechanisms modulating the course of infection are most likely of an
immunologic nature, including primarily suppressor T cell interactions.
Thus, the periparasitic granuloma, mainly composed of macrophages,
myofibroblasts and T cells, contains a large number of CD4+ T cells
in patients with abortive or died-out lesions, whereas in patients with
active metacestodes the number of CD8+ T cells is increased. An
immunosuppressive process is assumed to downregulate the lymphoid
macrophage system. Conversely, the status of cured AE is generally
reflected by a high in-vitro lymphoproliferative response. The cytokine
mRNA levels following E. multilocularis antigen stimulation of lymphocytes
show an enhanced production of Th2-cell cytokine transcripts IL-3, IL-4
and IL-10 in patients, including a significant IL-5 mRNA expression in
patients and not in healthy control donors. A lack or deficiency of Th cell
activity such as in advanced AIDS is associated with a rapid and
Page 7 of 31
unlimited growth and dissemination of the parasite in AE, recovery of the
T cell status in AIDS is prognostically favorable.
More detailed information about the host-parasite interplay that decides
about the outcome of infection has been achieved with the murine
model of AE. The involvement of cellular immunity in controlling the
infection is strongly suggested by the intense granulomatous infiltration
observed in the periparasitic area of lesions. Immunodeficient athymic
nude and SCID mice exhibited high susceptibility to infection and
disease, thus suggesting that the host cell mediated immune response
plays an important role in suppressing the larval growth. E. multilocularis
appears to induce skewed Th2-responses. Based on in vitro and in vivo
studies, Th2 dominated immunity was more associated with increased
susceptibility to disease, while Th1 cell activation through IL-12, IFN .g,
TNF.a and IFN.a was suggested to correlate with a more protective
immunity in AE. Nevertheless, effective suppression of larval growth by
means of an immunological attack is hampered by the fact, that the
parasite synthesizes a carbohydrate-rich laminated layer in order to be
protected from host effector mechanisms, as outlined above.
Basically, the larval infection with Echinococcus multilocularis begins with
the intrahepatic postoncospheral development of a metacestode that – at
its mature stage - consists of an inner germinal and the outer laminated
layer as discussed above [4]. Several lines of evidence obtained in vivo
and in vitro indicate the important bio-protective role of the laminated
layer, e.g. as to protect the germinal layer from nitric oxide produced by
periparasitic macrophages and dendritic cells, and also to prevent
immune recognition by surrounding T cells. On the other hand, the high
periparasitic NO production by peritoneal exudate cells contributes to
periparasitic immunosuppression [7], explaining why iNOS deficient mice
exhibit a significantly lower susceptibility towards experimental infection
[8]. The intense periparasitic granulomatous infiltration indicates an
intense host-parasite interaction, and the involvement of cellular
immunity in control of the metacestode growth kinetics is strongly
suggested by experiments carried out in T cell deficient mouse strains [9].
Carbohydrate components of the laminated layer, as the Em2(G11) and
Em492 components discussed above, yield immunomodulatory effects
that allow the parasite to survive in the host. I.e., the IgG response to the
Em2(G11)-antigen takes place independently of alpha-beta+CD4+ T cells,
and in the absence of interactions between CD40 and CD40 ligand [10].
Such parasite molecules also interfere with antigen presentation and cell
activation, leading to a mixed Th1/Th2-type response at the later stage of
infection. Furthermore, Em492 [11] and other (not yet published) purified
parasite metabolites suppress ConA and antigen-stimulated splenocyte
proliferation. Infected mouse macrophages (AE-MØ) as APCs exhibited a
reduced ability to present a conventional antigen (chicken ovalbumin,
C-Ova) to specific responder lymph node T cells when compared to
normal MØ [12].
Echinococcus granulosus parasitizes as a small tapeworm the small
intestine of dogs and occasionally other carnivores. The shedding of
gravid proglottids or eggs in the feces occurs within 4–6 weeks after
infection of the definitive host. Ingestion of eggs by intermediate host
animals or humans results in the development of a fully mature
metacestode (i.e. hydatid cyst) over a period of several months to years.
Infections with E. granulosus occur worldwide, however predominantly in
countries of South and Central America, the European and African part of
the Mediterranean area, the Middle East and some sub-Saharan countries,
Russia and China. Most cases observed in Central Europe and the USA
are associated with immigrants from highly endemic areas. Various strains
of E. granulosus have been described, and differ especially in their
infectivity for intermediate hosts such as humans. The most important
strains for human infection include sheep (G1) and cattle (G5) as
intermediate hosts.
Cystic echinococcosis (CE) is clinically related to the presence of one or
more well-delineated spherical primary cysts, most frequently formed in
the liver, but other organs such as the lungs, kidney, spleen, brain,
heart and bone may be affected too. Tissue damage and organ
dysfunction result mainly from this gradual process of space-occupying
displacement of vital host tissue, vessels or parts of organs.
Consequently, clinical manifestations are primarily determined by the
site, size and number of the cysts, and are therefore highly variable.
Accidental rupture of the cysts can be followed by a massive release of
cyst fluid and hematogenous or other dissemination of protoscolices.
This can result in anaphylactic reactions and multiple secondary cystic
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echinococcosis (as protoscolices can develop into secondary cysts
within the same intermediate host). The parasite evokes an immune
response, which is involved in the formation of a host-derived
adventitious capsule. This often calcifies uniquely in the periphery of
the cyst, one of the typical features found in imaging procedures. In
the liver there may be cholestasis. Commonly, there is pressure atrophy
of the surrounding parenchyma. Immunologically, the coexistence of
elevated quantities of interferon IFN-g, IL-4, IL-5, IL-6 and IL-10 observed
in most of hydatid patients supports Th1, Th17 and Th2 cell activation
in CE. In particular, Th1 cell activation seemed to be more related to
protective immunity, whereas Th2 cell activation was related to
susceptibility to disease.
Prevention of both CE and AE focuses primarily on veterinary
interventions to control the extent and intensity of infection in definitive
host populations, which may indirectly be approached by controlling the
prevalence in animal intermediate hosts also. The first includes regular
pharmacologic treatment and taking sanitary precautions for handling
domestic dogs and to prevent infection and egg excretion, respectively.
Regular praziquantel treatment of wild-life definitive host may contribute
to lower the prevalence in affected areas.
For diagnosis, imaging procedures together with serology will yield
appropriate results [13,14]. Sonography is the primary diagnostic
procedure of choice for hepatic cases [15], although false positives occur
in up to 10% of cases due to the presence of nonechinococcal serous
cysts, abscesses or tumors. Computerized tomography is the best
investigation for detecting extrahepatic disease and volumetric follow-up
assessment; magnetic resonance imaging (MRI) assists in the diagnosis by
identifying changes in the intra- and extrahepatic venous systems.
Ultrasonography is also helpful in following up treated patients as
successfully treated cysts become hyperechogenic. Calcification of
variable degree occurs in about 10% of the cysts. Aspiration cytology
appears to be particularly helpful in the detection of pulmonary, renal
and other nonhepatic lesions for which imaging techniques and serology
do not provide appropriate diagnostic support. The viability of aspirated
protoscolices can be determined by microscopic demonstration of flame
cell activity and trypan blue dye exclusion. Immunodiagnostic tests to
detect serum antibodies are used to support the clinical diagnosis of
both AE and CE.
Assessing the parasite viability in vitro following therapeutic interventions
may be of tremendous advantage when compared with the invasive
analysis of resected or biopsied samples. Such alternatives may be
offered by magnetic resonance spectrometry or positron emission
tomography (PET). The latter technique has recently been used for
assessing the efficacy of chemotherapy in AE. PET positivity actually
demonstrates periparasitic inflammatory processes due to a remaing
activity of the metacestode tissue. Serologic tests are more reliable in the
diagnosis of AE than CE. The use of purified E. multilocularis antigens
such as the Em2 antigen and recombinant antigens from the family of
EMR-proteins (EmII/3-10, EM10, EM4 and Em18, all four of them
harbouring an identical immunodominant oligopeptide sequence)
exhibits diagnostic sensitivities ranging between 91% and 100%, with
overall specificities of 98–100%. These antigens allow discrimination
between the alveolar and the cystic forms of disease with a reliability of
95%. Seroepidemiologic studies reveal asymptomatic preclinical cases of
human AE as well as cases in which the metacestode has died at an
apparently early stage of infection (see above). Serologic tests are of
value for assessing the efficacy of treatment and chemotherapy only
when linked to appropriate imaging investigations. Prognostically,
disappearance of anti-II/3–10 or anti-Em18 antibody levels coupled to PET
negativity indicates innactivation of AE. The management of CE and AE
follows the strategy recommended in the manual on echinococcosis
published in 2001 by the Office International des Epizooties and the
World Health Organisation.
References
1. Schweiger A, Ammann R, Candinas D, Clavien PA, Eckert J, Gottstein B,
Halkic N, Muellhaupt B, Prinz BM, Reichen J, Tarr PE, Torgerson PR,
Deplazes P: Human alveolar echinococcosis after fox population increase,
Switzerland. Emerg Inf Dis 2007, 13:878-82.
2. Gottstein B, Saucy F, Deplazes P, et al: Is a high prevalence of
Echinococcus multilocularis in wild and domestic animals associated
Page 8 of 31
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with increased disease incidence in humans? Emerg Infect Dis 2001,
7:408-12.
Reperant LA, Hegglin D, Fischer C, Kohler L, Weber JM, Deplazes P:
Influence of urbanization on the epidemiology of intestinal helminths of
the red fox (Vulpes vulpes) in Geneva, Switzerland. Parasitology Research
2007, 101:605-611.
Gottstein B, Deplazes P, Aubert M: Echinococcus multilocularis:
Immunological study on the “Em2-positive” laminated layer during in
vitro and in vivo post-oncospheral and larval development. Parasitology
Research 1992, 78:291-297.
Sailer M, Soelder B, Allerberger F, Zaknun D, Feichtinger H, Gottstein B:
Alveolar echinococcosis in a six-year-old girl with AIDS. J Pediatr 1997,
130:320-3.
Zingg W, Renner-Schneiter EC, Pauli-Magnus C, Renner EL, van Overbeck J,
Schläpfer E, Weber M, Weber R, Opravil M, Gottstein B, Speck RF: Swiss HIV
Cohort Study. Alveolar echinococcosis of the liver in an adult with
human immunodeficiency virus type-1 infection. Infection 2004,
32:299-302.
Dai WJ, Gottstein B: Nitric oxide-mediated immunosuppression following
murine Echinococcus multilocularis - infection. Immunology 1999,
97:107-116.
Dai WJ, Waldvogel A, Jungi T, Stettler M, Gottstein B: Inducible nitric oxide
synthase-deficiency in mice increases resistance to chronic infection
with Echinococcus multilocularis. Immunology 2003, 10:238-44.
Dai WJ, Waldvogel A, Siles-Lucas M, Gottstein B: Echinococcus
multilocularis proliferation in mice and respective parasite 14-3-3 gene
expression is mainly controlled by an alphabeta CD4 T-cell-mediated
immune response. Immunology 2004, 112:481-488.
Dai WJ, Hemphill A, Waldvogel A, Ingold K, Deplazes P, Mossmann H, et al:
Major carbohydrate antigen of Echinococcus multilocularis induces an
immunoglobulin G response independent of alpha beta(+) CD4(+) T
cells. Inf Immun 2001, 69:6074-6083.
Walker M, Baz A, Dematteis S, Stettler M, Gottstein B, Schaller J, et al:
Isolation and characterization of a secretory fraction of Echinococcus
multilocularis metacestode potentially involved in modulating the hostparasite interface. Infect Immun 2004, 72:527-36.
Mejri N, Gottstein B: Intraperitoneal Echinococcus multilocularis infection
in C57BL/6 mice inhibits the up-regulation of B7-1 and B7-2 costimulator expression on peritoneal macrophages and causes failure to
enhance peritoneal T cell activation. Parasite Immunol 2006, 28:373-385.
Ammann RW, Renner EC, Gottstein B, Grimm F, Eckert J, Renner EL, Swiss
Echinococcosis Study Group: Immunosurveillance of alveolar
echinococcosis by specific humoral and cellular immune tests:
prospective long-term analysis of the Swiss chemotherapy trial (19762001). J Hepatol 2004, 41:551-59.
Pawlowski ZS, Eckert J, Vuitton DA, et al: Echinococcosis in humans:
clinical aspects, diagnosis and treatment. WHO/OIE Manual on
echinococcosis in humans and animals. Paris: WHO/OIE Eckert J et al. 2001,
20-71.
WHO: International classification of ultrasound images in cystic
echinococcosis for application in clinical and field epidemiological
settings. Acta Trop 2003, 85:253-61.
S6
Dogs and echinococcosis in Iceland
Sigurdur Sigurdarson
The Icelandic Food- and Vetarinary Authority Austurvegur 64, 800 Selfoss,
Iceland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S6
History: Hydatid disease was first described in Icelandic literature about
the year 1200. According to the first qualified physician in Iceland, Bjarni
Pálsson (1719-1779) was echinococcosis about 1760 one of the most
frequent diseases among the human population, and was also commonly
observed in sheep and cattle. Autopsies and questionaries indicate that
20-25% of the inhabitants might have been infested by hydatidosis about
1850. The nature of the disease was still unknown at that time. The dog
population was estimated to be 15.000-20.000, or about one dog for
every three or four people. At the same time there were in Copenhagen
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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1 dog for every 30-32 persons. Obviously there were too many dogs in
Iceland. The sheep, cattle, dogs and humans lived in close contact. The
dogs often shared a room and even bed with the family, and were the
best playmate for the children. The people lived mostly in primitive
houses at that time and under primitive hygienic conditions. It is
therefore not wonder that the hydatid disease flourished as long as the
nature of the disease was still obscure.
In 1849 the Danish physician P.A.Schleisner (1819-1900) concluded that
one out of every six Icelanders suffered from hydatid disease. In 1862
doctor Harald Krabbe (1831-1917) from the Royal Veterinary and
Agricultural University in Copenhagen studied the hydatid problem in
Iceland. He found that 28 out of 100 dogs and most of the old sheep and
cows that were slaughtered were infested with echinococcus cysts.
Experiments he carried out in cooperation with an Icelandic physician Jón
C Finsen (1826-1885) proved the relationship between taenias in dogs and
the hydatid cysts in humans. Doctor H. Krabbe realized that most
important was to inform the people of the nature of the disease in order
to prevent the infestations of humans and animals with eggs of
the intestinal parasites of the dog. H. Krabbe was a chief adviser to the
Icelandic government on hydatid disease and prophylactic measures in the
period 1860-1890. His recommendations were followed strictly for more
than 100 years and partially they still are. New infestations by E. granulosus
practially dissappeared in Iceland the decade 1890-1900. That is based on
7333 autopsies of people performed in the period 1932-1966. And based
on 15.888 autopsies 1932-1982 only few human infestations occurred after
1900.The most recent human cases are a person born in 1937 who was
autopsied in 1960, another person born in 1905 operated 1984 and the
third person born in 1920 operated in 1988. In 1863 an autopsy survey of
100 dogs were carried out. E. granulosus was found in 28 of them, 75 dogs
carried T. marginata. In the period one hundred years later 200 dogs were
autopsied (1950-1960). T. marginata was found in 11 dogs but none of
them carried E. granulosus. Reports of meat inspectors from Icelandic
abattoirs did not record hydatid cysts in cattle, pigs and horses after 1961.
However in the period 1953-1979, cysts of echinococcus were recorded in
a total of 21 old ewes, all of which came from few farms on 2 small areas
in East-Iceland. There was an indication that the parasite had been
introduced to the country by an imported dog. After 1979 no hydatid cysts
have been found in any animal in Iceland.
Why so successful control of hydatid disease in Iceland: Echinococcosis is a great public health and economic problem in many
countries. It has been extremely difficult to eliminate it in many endemic
areas. Apparently it was done in Iceland rather easily. How?
The campaign against hydatid disease in Iceland was for more than one
century and partially still is based on Harald Krabbe´s recommendations:
1) Succesful information to the people. Most people in Iceland had lost
either relatives or friends as a victim to hydatid disease and the memory
of this disease was and still is dreaded. When people knew what to do,
strong parcipitation of both young and old was easy to activate.
2) Reduction of the dog population by taxes on all dogs, higher tax on
unnessesary dogs and a ban on keeping a dog without permission.
Outbrakes of distemper in 1870, 1888 and 1890 reduced the number of
dogs considerably, 3)Preventing the dog gaining access to raw offal
and burning cysts in organs 4) Caution in dealing with dogs, esp.
Children, 5) Yearly anthelmintic treatment of all dogs after the
slaughtering sesion. Some factors that assisted in the campaign: -Ceasing
of milking sheep on the farms, - improvement of the houses and hygiene,
-strictly practiced caution on the contact between dogs and animals/
people. Building of slaughterhouses all over the country in the period
1900-1920, then slaughtering on the farms almost ceased. The hydatid
disese was never found in horses, rodents or in wild animals in Iceland.
References
1. Pálsson PA: Echinococcosis and its elimination in Iceland. In a book in regi
of Ivan Kati´c Köbenhavn Harald Krabbe Dagbog fra Island 2000, 93-100,
Ferðasaga(1863, 1870, 1871).
2. Þórarinsdóttir KH: Echinokokkosen i Island og dr. Harald Krabbes indsats
for dens bekæmpelse. Köbenhavn OSVAL II – opgave, Köbenhavns
University, medicinske fakultet 1999.
3. Dungal N: New Zealand medical journal. 1957, 56:212-222.
4. Einarson M: Búnaðarrit. 1901, 15:125-164.
5. Einarson M: Dýralækningabók. Reykjavík 1931, 91-93, 232-235.
Page 9 of 31
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23.
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28.
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32.
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Finsen J: Iagtagelser angaaende Sygdomsforholdene I Island. Köbenhavn
1874, 177.
Hlíðar Sig E: Lækning húsdýra Akureyri. 1915, 66-68, 102-104.
Jónassen J: Ekinokoksygdommen belyst ved islandske Lægers Erfaring.
Köbenhavn 1882, 268.
Jónsson V: Skírnir. 1954, 128:134-175.
Jónsson S: Tidsskrift for Veterinærer. 1879, 137-178, 2. Rk., 9 Bd,.
Krabbe H: Athugasemdir handa Íslendingum um sullaveikina og varnir
móti henni. Köbenhavn 1864, 18.
Krabbe H: Helmintologiske Undersögelser I Danmark og paa Island med
særlig hensyn til Blæreormlidelserne ............ paa Island. Köbenhavn 1865,
64.
Magnússon G: Yfirlit um sögu sullaveiki á Íslandi. Reykjavík 1913, 83.
Pálsson PA, Vigfússon H, Henriksen K: Læknablaðið. 1971, 57:39-51.
Sigurðsson J: Nordisk Medicinhistorisk Årsbog. 1970, 182-198.
Thoroddsen Þ: Landbúnaður á Íslandi. 1922, 2:73-84.
Bang B: Biografier af lærere ved De Danske Veterinærskole. Medlemsblad
for Den Danske Dyrlægeforening, 6. Aargang, Köbenhavn 1923, 93-99.
Schultz Forlag JH: Dansk Biografisk Leksikon. Bnd. 13 Köbenhavn 1938.
Dungal N: Er sullaveikin að hverfa á Íslandi? Læknablaðið 1942, 28:121-128.
Dungal N: Eradication of Hydatid Disease in Iceland. New Zealand Medical
Journal 1957, 56:212-222.
Eschricht D: Afhandling om de Hydatider, der fremkaldte den I Island
endemiske leversyge. I: Oversigt over Videnskabernes Selskabs Forhandlinger
1857, 211-239.
Faust EC: Echinococcus Disease. Nelson Loose-Leaf Medicine II New York, 1
1920, 433.
Fenger E: Plan til en Forelæsnings-Cyclus. Kbh 1843.
Fridriksson G: Saga Reykjavíkur 1870-1940. Reykjavík: Iðunn 1994.
Garcia LS, Bruckner DA: Diagnostic medical parasitology. 1997.
Jónasson J: Íslenskir Þjóðhættir. 3 utg Reykjavík: Ísafoldarprentsmiðja 1961.
Jónsson V: Sullaveikirannsóknir Jóns Finsen og Haralds Krabbe. Skírnir
1954, 128:134-175.
Krabbe H: Om Echinokokkerne, I. del I: Ugeskrift for Læger. Række 2 1862,
37(15):225-235.
Krabb H: Om Echinokokkerne, II. del. I: Ugeskrift for Læger. 2 Række 1862,
37(16):241-259.
Krabbe H: Echinokokksygdommen på Island. Ugeskrift for læger 1864,
41(1):1-19, 2. Række.
Krabbe H: Blæreormlidelserne på Island og de imod dem trufne
Foranstaltninger. Tidsskrift for Veterinærer 1865, 20:205-222, 2. Række.
Krabbe H: Helmintologiske Undersögelser I Danmark og paa Island med
særlig hensyn til Blæreormlidelserne paa Island. 1: Det Kongelige Danske
Videnskabernes Selskabs Skrifter 5. Række, naturvidenskabelig og mathematisk
Afdeling 1865, 7:347-408, Köbenhavn, 64 pp.
Leared A: Athugasemdir um sullaveikina á Íslandi. Íslendingur 1862,
3:105-106.
Leared A: Athugasemdir um sullaveikina á Íslandi. Þjóðólfur 1862, 15:33-34.
Magnússon G: Yfirlit yfir sögu sullaveikinnar á Íslandi. Fylgirit Árbókar
Háskóla Íslands fyrir háskólaárið 1912-1913. Reykjavík 1913.
Einarsson Matthías: Hvernig fær fólk sullaveiki? Læknablaðið 1925,
11:98-100.
Nielsen JB: Parasitologi – et kompendium. Köbenhavn: FADL´s Forlag, 2
1994.
Olafsens og Povelsens Reise gennem Island. Soröe 1772.
Pálsson PA, Vigfússon H, Henriksen K: Læknablaðið. 1971, 57:39-51.
Pálsson PA: Echinococcosis and its elimination in Iceland. Hist Med Vet
1976, 1:4-10.
Pálsson PA: Echinococcosis in Iceland – historical review. XVII.
Interrnational Congress of Hydatology, Limassol, Cyprus, nov. 6-10 1996.
Pétursson J: Lækningabók fyrir Almúga. Köbenhavn: Udg. Af Thorsteinn
Jónsson 1834.
Roberts L, Janovy J: Foundations of Parasitology. Boston: Wm.C. Brown
Publishers, 5 1996.
Schleisner PA: Island undersögt fra et lægavidenskabeligt Synspunkt.
Köbenhavn: Boghandler C.G.Iversen 1849.
Sun T, Rackson M, Farber B: Current status of Hydatid Disease. Digestive
Diseases 1988, 6:170-184.
Thorsteinsson B, Jónsson B: Íslandssaga til okkar daga. Reykjavík: Sögufélag
1991.
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S7
Toxoplasma gondii in the Subarctic and Arctic
Kristin W Prestrud1*, Kjetil Åsbakk1, Antti Oksanen2, Anu Näreaho3,
Pikka Jokelainen3
1
Norwegian School of Veterinary Science, Department of Food Safety and
Infection Biology, Section of Arctic Veterinary Medicine, Tromsø, Norway;
2
Finnish Food safety Authority Evira, Fish and Wildlife Health Research Unit
(FINPAR), Oulu, Finland; 3Department of Basic Veterinary Sciences, Faculty of
Veterinary Medicine, University of Helsinki (FINPAR), Helsinki, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S7
Summary: The coccidian protozoan Toxoplasma gondii has a world-wide
distribution. It causes toxoplasmosis, a potentially very serious disease to
humans and other warm-blooded animals. Infection has in many studies
been shown to be rather common in the Nordic countries also, where its
prevalence both in domestic animals and wildlife can be explained by
contacts with cats and their faeces, cats and wild felids being the only
definitive hosts of the parasite known.
Before the discovery of the complete life cycle of the parasite, other
infection routes to animals were studied e.g. in Russia, where lateral
transmission of infection in a reindeer herd was reported. The vehicle of
infection was apparently body fluids, such as e.g. saliva and lacrimal fluid
containing parasite tachyzoites, which might invade another reindeer via
mucosal membranes. According to the finding, toxoplasmosis might be
apprehended to be also a sexually transmitted disease. Following the
discovery of the pivotal role of the cat in the epidemiology of T. gondii,
possible alternative pathways of infection have generally been ignored. In
Fennoscandian semi-domesticated reindeer, a clear association of the
seroprevalence of antibodies to T. gondii was seen with the degree of
domestication, and, thus, with cat contacts [1].
In the high Arctic of Svalbard, there is a considerably high seroprevalence
of infection both in polar bears and Arctic foxes [2-4]. The source of
infection is unlikely to be found in the seals constituting the major part
of the polar bear’s diet, as in one study, antibodies were not found in
North Atlantic marine mammals. However, in other, less arctic and
remote, cetacean and pinniped populations studied, T. gondii infection
has been found.
Because Svalbard reindeer and sibling voles studied have been free from
T. gondii infection, it can be assumed that sexual stages of infection (in
definitive hosts) leading to oocyst production is not a major part of the
Svalbard T. gondii life cycle [2]. Then, carnivores probably get the
infection with food, anyhow. Cannibalism is considered common in polar
bears and Arctic foxes, and probably can explain a lot. One parasite
isolate from an Arctic fox proved to belong to the Type II strain, the
predominant T. gondii lineage in the world [3]. This somewhat objects to
the suggested idea of a specific Arctic life cycle of the parasite, but
incorporates the Arctic to the global T. gondii infection network. Further
support to the hypothesis is gained from the finding that Svalbard
barnacle geese (Branta leucopsis) are rather commonly infected. They may
get the infection when wintering in Scotland. So, perhaps migratory birds
are important in T. gondii globalisation.
Cats are crucial to T. gondii epidemiology. However, the Arctic example
proves that the successful parasite can thrive even in the absence of cats.
References
1. Oksanen A, Åsbakk K, Nieminen M, Norberg H, Näreaho A: Antibodies
against Toxoplasma gondii in Fennoscandian reindeer — Association
with the degree of domestication. Parasitology International 1997,
46:255-261.
2. Prestrud KW, Åsbakk K, Fuglei E, Mørk T, Stien A, Ropstad E, Tryland M,
Gabrielsen GW, Lydersen C, Kovacs KM, Loonen MJ, Sagerup K, Oksanen A:
Serosurvey for Toxoplasma gondii in arctic foxes and possible sources of
infection in the high Arctic of Svalbard. Vet Parasitol 2007, 150:6-12.
3. Prestrud KW, Dubey JP, Åsbakk K, Fuglei E, Su C: First isolate of
Toxoplasma gondii from arctic fox (Vulpes lagopus) from Svalbard. Vet
Parasitol 2008, 151:110-114.
4. Oksanen A, Åsbakk K, Prestrud KW, Aars J, Derocher A, Tryland M, Wiig Ø,
Dubey JP, Sonne C, Dietz R, Andersen M, Born EW: Prevalence of antibodies
against Toxoplasma gondii in polar bears (Ursus maritimus) from Svalbard
and East Greenland. J Parasitol 2008, 1, [Epub ahead of print].
Page 10 of 31
S8
Trichinella in the North
Niina Airas1, Seppo Saari1, Taina Mikkonen1, Anna-Maija Virtala1, Jani Pellikka1,
Antti Oksanen2, Marja Isomursu2, Antti Sukura1*
1
Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine,
University of Helsinki, Helsinki, Finland; 2Finnish Food Safety Authority Evira,
Oulu, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S8
Background: Endemic human trichinellosis has been rare in Norway,
Sweden and Finland. In Norway the last outbreak involving five persons
is from 1953 and before that there were reported six epidemics with 711
patients since 1881 (reference in [1]). In Sweden 10 outbreaks involving
504 patients were documented 1917-1969 (reference in [2]). In Finland
only eight human cases have been reported since 1890, the latest being
three hunters at 1977 who got the infection from bear meat (reference
in [1]).
Sporadic cases of trichinellosis in production animals have been
detected in pig meat inspection in these countries. In Norway there
was a peak of positive pigs in the 1950’s and 1960’s but since 1981 no
positive finding in pigs has been reported. In Sweden, 127 positive pigs
were reported 1970-1999 and no cases since 2000. The first infected
Finnish pig was found 1954, and the total number of positive pigs in
fifty years was up to 714 (1954-2003). There was a peak of cases in the
1980’s and 90’s when a total of 671 pigs were found positive. During
1981-2000, the positive animals originated from 0-19 farms yearly. Since
Figure 1 (abstract S8) Prevalence gradient is seen in all sampled
animal species with sample size over 100 individuals.
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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2004 no trichinella has been found in pigs. The decrease in Trichinella
prevalence and incidence in domestic swine has been speculated to be
due the change in Finnish swine industry since Finland joined the EU in
1995 [3]. During recent years, the industry has moved towards largescale enterprises with corporative ownership with new facilities. These
are better protected against the Trichinella infection commonly present
in surrounding wildlife in Finland [3]. High sylvatic trichinellosis
prevalence has been reflected to farmed wild boars in which
condemnation due trichinelllosis has been relatively more common
than in pig. To clarify the spatial variation of sylvatic trichinella
prevalence suggested in earlier studies, a new Finnish sample set was
analyzed.
Material and methods : Muscle samples of 2487 carnivorous wild
animals from eight host species during 1999-2005 were collected by
volunteer hunters. Molecular identification was performed on larval
isolates with multiplex PCR.
Results : Out of 2487 animals analyzed, Trichinella spp were revealed
from 618 animals. Different host species showed variable sample
prevalence (range: 0- 46 %). Almost half of the lynx harboured
Trichinella spp (46%); in species rank, lynx were followed by wolves
(39%), raccoon dogs (28%), and red foxes (19%). Lower than ten
percent prevalences were detected in sampled pine martens, badgers,
bears, and otters. No larvae were detected from mink. The overall
Trichinella prevalence from all sampled host species was not
geographically equally distributed varying from 2.6% (Lapland) up to
67% on different game districts (P< 0.001), showing obvious
diminishing gradient form south to north (figure 1).
Molecular analysis was performed with 328 larval isolates. Trichinella
species were successfully identified from 303 animals, from 25 animals
amplification did not give specific reaction (7.6%). Four species were
discovered: T. spiralis, T. nativa, T. britovi, and T. pseudospiralis. Single
Trichinella species were revealed from 281 (93%) of the infected host
animals and 22 (7%) showed mixed infections. T. nativa was the most
common single species (80.1%) followed by T. spiralis (12.8%) T. britovi
(6.0%) and T. pseudospiralis (1.1%), which was found in single infection
in only three animals but in mixed infection in four more individuals.
From mixed infections, never more than two different species were
found, but all possible two-species combinations of four species were
discovered. Species geographic distribution showed that all four
species were discovered only from the southern part of the country; in
the middle and northern part, only T. nativa and T. spiralis were
revealed.
The parasite burden was not normally distributed. Different hosts showed
variations in the infection density and also different Trichinella species
made different parasite burdens. There was a significant interaction
between animal species and Trichinella species showing for example that
T. spiralis gave a higher larval burden in raccoon dog than in other
animals. However, in raccoon dogs, the host specie with the highest
burden, infection densities did not differ between infecting Trichinella
species.
Conclusion: In Finland sylvatic trichinellosis is very common with big
geographical differences showing clear diminishing along south to north
gradient. T. nativa was the most prevalent species in the country but,
remarkably, the domestic species T. spiralis was isolated from 15% of
sylvatic isolations. T. spiralis was recovered all around in Finland.
Intriguingly, T. spiralis was revealed form the very north in a fox in an
area where never any domestic outbreak of trichinellosis has been
reported, and seldom any swine has been seen, indicating that T. spiralis
may exist in sylvatic cycle without external sources from synanthropic
animals.
When population sizes are considered, the major reservoir animals in
Finland are the raccoon dog and the red fox.
References
1. Oivanen L: Endemic trichinellosis – experimental and epidemiological
studies. Dissertation 2005, Yliopistopaino, Helsinki.
2. Pozio E, Christensson D, Steen M, Marucci G, La Rosa G, Bröjer C, Mörner T,
Uhlhorn H, Ågren E, Hall M: Trichinella pseudospiralis foci in Sweden. Vet
Parasitology 2004, 125:335-342.
3. Oivanen L, Oksanen A: Synanthropic Trichinella infection in Finland. Vet
Parasitol 2009, 159:281-284.
Page 11 of 31
S9
Detection of infection with Angiostrongylus vasorum (Nematoda,
Strongylida) by PCR
Mohammad Al-Sabi1*, Pia Webster2, Jacob Willesen3, Peter Deplazes4,
Alexander Mathis4, Christian Kapel1
1
Department of Agriculture and Ecology, University of Copenhagen, DK-1871
Frederiksberg C, Denmark; 2Department of Disease Biology, University of
Copenhagen, DK-1871 Frederiksberg C, Denmark; 3Small animal hospital,
University of Copenhagen, DK-1871 Frederiksberg C, Denmark; 4Institute of
Parasitology, University of Zurich, CH-8057 Winterthurerstrasse 266A, Zurich,
Switzerland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S9
Background: The French heart worm Angiostrongylus vasorum is a
parasitic nematode of the pulmonary arteries and heart of canines often
with severe and in some cases fatal outcome. The diagnosis is based on
detection and species identification of larvae in faeces which can be
problematic in Veterinary praxis especially in cases with low excreting
animals. A reliable technique is thus needed for correct diagnosis and
estimation of the true prevalence of infection in a population as well as
for monitoring and control campaigns.
Materials and methods: A PCR was developed from the ITS2 region of
the rDNA of A. vasorum. The sensitivity of the primers was tested with
DNA from adult A. vasorum from a naturally infected fox and first stage
larvae (L1) from an experimentally infected foxes. The specificity of the
primers was tested against DNA from the most common helminth
parasites of canines in Denmark and neighbouring countries. Furthermore
the PCR system was applied as a confirmative test in a screening study of
Danish hunting dogs and an epidemiological study of helminth parasites
of wildlife in Denmark.
Results: The designed primers were very sensitive and could detect a
single A. vasorum L1. The primers were also very specific and did not
react with DNA from any of the common canine helminths. When used
as a confirmative test, the PCR system proved to be robust and easy to
work with detecting a single larva, and for use in post mortem
examination of wildlife. There are practical problems that can face the
PCR system such as isolating dead larvae from frozen samples and the
known problem of intermittent larval excretion in dogs. These two
problems can be solved by isolation of larvae by sieving instead of by
Baermann sedimentation if samples were frozen, and examining
consecutive fresh faecal samples.
Conclusions: We were able to design a new PCR to detect DNA of
A. vasorum in canines. The test proved to be very sensitive and specific
when tested in clinical and epidemiological studies. The test will be
further applied in many epidemiological and clinical studies to come.
S10
Wild life surveillance on Echinococcus multilocularis in Sweden
Birgitta Andersson*, Bodil Christensson, Susanne Johansson,
Eva Osterman Lind, Göran Zakrisson
National Veterinary Institute, Department of Virology, Immunobiology and
Parasitology, Section for Parasitological Diagnostics; SE-751 89 Uppsala,
Sweden
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S10
Background: Echinococcus multilocularis is a tapeworm whose adult
stages parasitize the intestine of canids such as foxes and wolves. Also
domestic dogs and cats can act as definitive hosts. The sylvatic life
cycle includes small rodents as intermediate hosts but humans may
become accidentally infected by ingestion of eggs. Sweden, Finland,
UK, Ireland, and Malta are considered to be free of this parasite and
therefore have maintained their national rules as regards deworming of
pets at movement into the countries. According to the EC regulation,
these national rules can be applied during a transitional period to
2010.
In order to confirm the absence of E. multilocularis in Sweden, monitoring
of foxes is being carried out continuously. These investigations are
financed by the Swedish government.
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
http://www.actavetscand.com/supplements/52/S1
Materials and methods: In 2007, 245 red foxes were shot and sent to
SVA by local hunters in different parts of Sweden. To kill potential
tapeworm eggs, the carcasses were placed in –80° C for at least one
week before sampling. Faecal samples were then collected from the
rectum and sent to Switzerland for testing by coproantigen ELISA
(Deplazes et al., 1999). Forty-eight foxes that were positive in the ELISA
and additional 28 randomly selected individuals were also examined by a
sedimentation technique according to the OIE guidelines.
Results and discussion: Forty-eight foxes out of 245 were positive for
Echinococcus sp. by the coproantigen ELISA. With the sedimentation
technique however, Echinococcus sp was not detected in any of the
examined animals, including those who had been positive in the ELISA.
One possible explanation for obtaining false positive ELISA results was
that some kind of cross-reaction had taken place. The majority of the
foxes were infected with other parasites, for example Taenia sp,
Mesocestoides sp, Alaria alata, Toxocara canis, Toxascaris leonina.
Conclusions: There is a need for good screening methods with high
sensitivities and specificities. The results obtained by the sedimentation
technique indicate that Sweden was still free from the fox tapeworm in
2007.
Reference
1. Deplazes P, Alther P, Tanner I, Thompson RCA, Eckert J: Echinococcus
multilocularis coproantigen detection by enzyme-linked immunosorbent
assay in fox, dog and cat populations. J. Parasitol 1999, 85:115-121.
S11
Emerging alveolar echinococcosis (AE) in humans and high prevalence
of Echinococcus multilocularis in foxes and raccoon dogs in Lithuania
Mindaugas Šarkūnas1*, Rasa Bružinskaitė1,4, Audronė Marcinkutė2,
Kęstutis Strupas3, Vitalijus Sokolovas3, Alexander Mathis4, Peter Deplazes4
1
Department of Infectious Diseases, Lithuanian Veterinary Academy, Tilžės str.
18, LT–47181, Kaunas, Lithuania; 2Clinic of Infectious Diseases, Microbiology
and Dermatovenereology, Vilnius University, Lithuania; 3Santariškių Clinic,
Vilnius University, Lithuania; 4Institute of Parasitology, WHO Collaborating
Centre for Parasitic Zoonoses, University of Zürich, Switzerland
E-mail: [email protected]
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S11
Summary: The presence of the most important definitive and
intermediate hosts suggests that conditions for the live cycle of
E. multilocularis are favorable in Lithuania. While the main rodent hosts
have not been investigated systematically in Lithuania, E. multilocularis
has already been identified in one of 5 muskrats (Ondatra zibethicus)
captured in the Šilutė district. The high prevalence of E. multilocularis in
red foxes and raccoon dogs as well as a notable increase of AE
in humans document that E. multilocularis is of emerging concern in
Lithuania. The human AE cases were recorded from many parts of the
country suggesting that the whole territory of Lithuania should be
considered as an endemic area for E. multilocularis. Considering the long
prepatent period of AE in humans we suggest that this zoonosis is
present in the area investigated for at least a few decades.
Introduction: Echinococcus multilocularis is a small tapeworm exploiting
mainly wild animals with the red fox (Vulpes vulpes) being the crucial
definitive host in Europe [1]. Dogs and raccoon dogs are also highly
susceptible definitive hosts of E. multilocularis, while reproduction of this
parasite is significantly lower in cats as shown by experimental infections
[2]. Humans may get infected by uptake of eggs, and the tumor-like
growth of the metacestode stage mainly in the liver may lead to a
serious disease – alveolar echinococcosis (AE).
Although a rare disease, the numbers of AE cases have increased in
endemic areas in Central Europe [3]. AE is of considerable public health
importance because of its high lethality if untreated and high treatment
costs [4].
The known central–European endemic area of E. multilocularis has
expanded during the 1990s especially to the North and East [5], and the
parasite was recently reported in the Baltic and neighboring regions i.e.
Poland [6], Belarus [7] and Estonia [8]. The presence of the most
important definitive and intermediate hosts [9] suggests that conditions
for the live cycle of E. multilocularis are therefore favorable in Lithuania.
While these main rodent hosts have not been investigated systematically
Page 12 of 31
in Lithuania, E. multilocularis has already been identified in one of 5
muskrats (Ondatra zibethicus) captured in the Šilutė district [10]. The high
prevalence of E. multilocularis in red foxes and raccoon dogs as well as a
notable increase of AE in humans was also recently documented [11,12].
Human infection: In the early eighties, sporadic cases of cystic
echinococcosis caused by the larval stage of E. granulosus were
diagnosed in humans in Lithuania. However, during the last decades, the
diagnostic techniques have improved and the incidence of human AE has
risen to considerable levels, with an increasing concern among the
human population and the health authorities.
From 1997 to July 2008, 96 AE cases have been diagnosed at the State
Hospital for Tuberculosis and Infectious Diseases in cooperation with the
Santariškių Clinic (Vilnius University). Eighty-one percent of AE patients
were farmers or persons involved in agricultural activities. Most of the
patients (59%) owned dogs. The AE cases were recorded from many parts
of the country suggesting that the whole territory of Lithuania should be
considered as an endemic area [11,12].
Animal infection: The helminth fauna of carnivores from Lithuania was
investigated in earlier studies, but no record was made on
E. multilocularis [13,14]. The methods used in these studies are not well
documented but the reported findings of E. granulosus as well as other
small helminths in dogs and wolves indicate that E. multilocularis would
most probably have been detected in the 122 foxes investigated, at least
if highly prevalent at that time.
In neighboring Poland, E. multilocularis in red foxes was recorded for the
first time in the Gdansk region in 1995 [6] which is close to the
Lithuanian border. Interestingly, the parasite’s prevalence in red foxes
(35%) in the southern part of Lithuania [11] is comparable to the one
(34.5%) reported from Poland [15]. However, based on these limited data,
it remains unclear whether the East Baltic region is a newly established
endemic area of an extending distribution to the eastern part of Europe,
or just a hitherto unnoticed one.
In Lithuania, E. multilocularis was detected in 158 (58.7%, 95%
CI 50.2%–64.1%) of 269 red foxes examined. It was present in foxes from
most tested localities with the highest prevalence of 62.3% (CI 49.0–74.4%)
being observed in the Kaunas district. Mean worm burden was 1309
(1-20,924) worms per fox in this district [11]. It was found that 17% of the
infected adult red foxes were harboring heavy infections (>1000 worms
per animal) while none of the juvenile foxes were heavily infected. This
finding differs from other studies suggesting that juvenile foxes play a
more important role in the life cycle of E. multilocularis [16,17]. However,
our result may be biased by the low number of juvenile foxes investigated.
The high prevalence (58.7%) of E. multilocularis in red foxes in the
examined areas suggests that these animals may play the most important
role in the zoonotic transmission of this tapeworm in Lithuania.
The raccoon dog is a highly susceptible definitive host for E. multilocularis
[2] and there are reports on infected animals from Germany [18], Poland
[19] and Lithuania [11]. However, the prevalence of E. multilocularis in
raccoon dogs is relatively low in these countries when compared to those
of the red foxes (2.7%, 8% and 10%, respectively). Further, the
significance of the raccoon dogs regarding the transmission of
E. multilocularis to the intermediate host population is poorly understood.
In addition to the morphological detection of E. multilocularis in one of 5
muskrats (Ondatra zibethicus) captured in the Šilutė district of Lithuania
[10], infertile and calcified metacestodes of E. multilocularis were
identified by PCR in 0.4% (3/685) of pigs, and 2 of 240 examined dogs
(0.8%) from the same area excreted E. multilocularis eggs [20] as
characterised by multiplex PCR using primers specific for E. granulosus,
E. multilocularis and Taenia spp. according to Trachsel et. al. [21].
Conclusions: The identification of AE in pigs and of E. multilocularis
in dogs demonstrates that transmission of E. multilocularis is occurring in
the rural environment in close vicinity to the human population. Red
foxes may be considered as the most important species for transmission
of E. multilocularis to humans while the respective epidemiological
importance of rural dogs and raccoon dogs is still unknown and deserves
further studies.
The high number of human AE cases and the high prevalence of
E. multilocularis in definitive wild hosts as well as its presence in pigs and
dogs document that E. multilocularis is of emerging concern in Lithuania.
Considering the long prepatent period of AE in humans we suggest that
this zoonosis is present in the area investigated for at least a few decades.
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
http://www.actavetscand.com/supplements/52/S1
Acknowledgments: The study was financially supported by the Food
and Agriculture Organization of the United Nations (FAO, project TCP/
LIT/ 3001 (T)), the SwissBaltNet (supporter: GEBERT RÜF STIFTUNG),
Lithuanian Veterinary Academy, Hospital of Tuberculosis and Infectious
Diseases and Santariškių Clinic of Vilnius University. The authors wish
to thank Regina Virbalienė and Jolanta Žiliukienė, Parasitology
Laboratory, National Public Health Centre, Aušrinė Barakauskienė, MD,
PhD, National Centre for Pathology and Jonas Valantinas MD, PhD,
Santariškių Clinic for their valuable assistance in diagnosing human
echinococcosis.
References
1. Eckert J, Deplazes P: Biological, epidemiological, and clinical aspects of
echinococcosis, a zoonosis of increasing concern. Clin Microbiol Rev 2004,
17:107-35.
2. Kapel CM, Torgerson PR, Thompson RC, Deplazes P: Reproductive potential
of Echinococcus multilocularis in experimentally infected foxes, dogs,
raccoon dogs and cats. Int J Parasitol 2006, 36:79-86.
3. Schweiger A, Ammann RW, Candinas D, Clavien PA, Eckert J, Gottstein B,
Halkic N, Muellhaupt B, Prinz BM, Reichen J, Tarr PE, Torgerson PR,
Deplazes P: Human alveolar ecihnococcosis after fox population increase,
Switzerland. Emerg Infect Dis 2007, 13(6):878-882.
4. Torgerson PR, Schweiger A, Deplazes P, Pohar M, Reichen J, Ammann RW,
Tarr PE, Halkik N, Müllhaupt B: Alveolar echinococcosis: from a deadly
disease to a well-controlled infection. Relative survival and economic
analysis in Switzerland over the last 35 years. J Hepatol 2008, 49(1):72-77.
5. Romig T, Dinkel A, Mackenstedt U: The present situation of
echinococcosis in Europe. Parasitol Int 2006, 55:S187-191.
6. Malczewski A, Rocki B, Ramisz A, Eckert J: Echinococcus multilocularis
(Cestoda), the causative agent of alveolar echinococcosis in humans first
record in Poland. J Parasitol 1995, 81:318-321.
7. Shimalov VV, Shimalov VT: Helminth fauna of red fox (Vulpes vulpes
Linnaeus, 1758) in southern Belarus. Parasitol Res 2003, 89:77-78.
8. Moks E, Saarma U, Valdmann H: Echinococcus multilocularis in Estonia.
Emerg Infect Dis 2005, 11(12):1973-1974.
9. Prūsaitė J, Mažeikytė R, Pauža D, Paužienė N, Baleišis R, Juškaitis R, et al:
Fauna of Lithuania. Mokslas, Vilnius 1988, (In Lithuanian).
10. Mažeika V, Paulauskas A, Balčiauskas L: New data on the helminth fauna of
rodents of Lithuania. Acta Zoologica Lituanica 2003, 13:41-47.
11. Bružinskaitė R: Epidemiology of Echinococcus species with reference to
helminths of red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes
procyonoides) in Lithuania. PhD Thesis Lithuanian Veterinary Academy,
Department of Infectious Diseases 2007.
12. Bružinskaitė R, Marcinkutė A, Strupas K, Sokolovas V, Deplazes P, Mathis A,
Eddi C, Šarkūnas M: Alveolar echinococcosis, Lithuania. Emerg Infect Dis
2007, 13(10):1618-1619.
13. Danilevičius E: Echinococcosis in Lithuanian SSR and immunodiagnosis of
echinococcosis in pigs. PhD Thesis Lithuanian Veterinary Institute 1964, (in
Russian).
14. Kazlauskas J, Prūsaitė J: Helminths of carnivores in Lithuania. Acta
Parasitologica Lituanica 1976, 12:33-40, (in Russian).
15. Gawor J, Malczewski A, Stefaniak J, Nahorski W, Paul M, Kacprzak E, et al:
Risk of alveococcosis for humans in Poland. Przegl Epidemiol 2004,
58:459-465, (in Polish).
16. Tackamnn K, Loschner U, Mix H, Staubach C, Thulke HH, Conraths FJ:
Spatial distribution patterns of Echinococcus multilocularis (Leucart
1863) (Cestoda: Cyclophyllidea: Taeniidae) among red foxes in an
endemic focus in Branderburg, Germany. Epidemiol Infect 1998,
120:101-109.
17. Hofer S, Gloor S, Muller U, Mathis A, Hegglin D, Deplazes P: High
prevalence of Echinococcus multilocularis in urban red foxes (Vulpes
vulpes) and voles (Arvicola terrestris) in the city of Zurich, Switzerland.
Parasitol 2000, 120:135-142.
18. Thiess A, Schuster R, Nockler K, Mix H: Helminth findings in indigenous
raccoon dogs Nyctereutes procyonoides (Gray, 1834). Berliner und
Munchener Tieraztlichr Wochenschrift 2001, 114:273-276, (in German).
19. Machnicka B, Dziemian E, Rocki B, Kolodziej-Sobocinska M: Detection of
Echinococcus multilocularis antigens in faeces by ELISA. Parasitol Res
2003, 91:491-496.
20. Bružinskaitė R, Šarkūnas M, Torgerson PR, Mathis A, Deplazes P:
Echinococcosis in pigs and intestinal infection with Echinococcus spp. in
dogs in Southwestern Lithuania. Vet Parasitol in press.
Page 13 of 31
21. Trachsel D, Deplazes P, Mathis A: Identification of eggs of canine Taeniids
by multiplex PCR. Parasitology 2007, 134:911-920.
S12
A survey for Toxoplasma gondii in red fox (Vulpes vulpes) from
Finnmark County, Norway
Renate Sjølie Andresen
Norwegian School of Veterinary Science, Department of Food Safety and
Infection Biology, Section of Arctic Veterinary Medicine, Stakkevollveien 23,
NO-9010 Tromsø, Norway
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S12
Summary: Samples (blood or tissue fluid) from 405 red foxes (Vulpes
vulpes) from Finnmark, Northern Norway, were assayed for antibodies
against T. gondii using the direct agglutination test (DAT). The proportion
of seropositive animals was 42.5 %, with no significant relationship
between sex and infection. The proportion of seropositives seemed to
increase with age, in agreement with findings in previous studies in other
species. Genotyping of brain tissue by PCR was not successful what
concerned T. gondii genomic DNA. This first report of Toxoplasma gondii
infection in Norwegian red foxes from Finnmark County indicates that
T. gondii is fairly common in red foxes from this area, and the high
seroprevalence might be explained by widespread of the parasite in the
diet of the foxes. This implies that the red fox is a host of significance in
the maintaining of T. gondii in this northern region.
S13
Toxoplasma gondii in Australian smallgoods
Tatjana Momcilovic
Norwegian School of Veterinary Science, P.O.Box 8146, 0030 Dep Oslo,
Norway
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S13
Summary: Toxoplasma gondii is one of the most common parasitic
infections of humans and other warm-blooded animals. In most adults it
does not cause serious illness, but severe disease may result from
infection of fetuses and immuno-compromised people. Consumption of
raw or undercooked meats has been consistently identified as an
important source of exposure to T. gondii. Several studies indicate the
potential failure to inactivate T. gondii in the processes of cured meat
products, referred to as smallgoods in Australia.
This publication presents a qualitative risk-based assessment of the
processing of ready-to-eat smallgoods. The raw meat ingredients are
rated with respect to their likelihood of containing T. gondii cysts and an
adjustment is made based on whether all the meat from a particular
source is frozen. Next the effectiveness of common processing steps to
inactivate T. gondii cysts are assessed, including addition of spices,
nitrates, nitrites and salt, use of fermentation, smoking and heat
treatment, and the time and temperature during maturation. It is
concluded that processing steps which may be effective in the
inactivation of T. gondii cysts include freezing, heat treatment and
cooking, and the interaction between salt concentration, maturation time
and temperature. The assessment is the illustrated using a Microsoft Excel
based software tool which was developed to facilitate the easy
assessment of four hypothetical smallgoods products.
S14
Echinococcus granulosus (‘pig strain’, G6/7) in Southwestern Lithuania
Mindaugas Šarkūnas1*, Rasa Bružinskaitė1,3, Audronė Marcinkutė2,
Alexander Mathis3, Peter Deplazes3
1
Department of Infectious Diseases, Lithuanian Veterinary Academy, Kaunas,
Lithuania; 2Clinic of Infectious Diseases, Microbiology and
Dermatovenereology, Vilnius University, Vilnius, Lithuania; 3Institute of
Parasitology, University of Zürich, Switzerland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S14
Background: Cystic echinococcosis (CE) of pigs is widespread and known
since many years in Lithuania [1]. Recently, the number of diagnosed
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
http://www.actavetscand.com/supplements/52/S1
cases of human CE began to increase [2] but only limited information is
available on the main epidemiological aspects of this zoonosis.
Material and methods: During 2005-2006, post slaughter examination
and morphological identification of cysts from pigs from small family
farms (n=612) and industrial farms (n=73) was performed. Dog fecal
samples (n=240) were collected in 12 villages and microscopically
examined by egg flotation/sieving (F/Si) [3] and modified McMaster
methods [4]). For the genetic identification of E. granulosus to species/
strain level, PCR was performed with DNA from typical hydatid cysts from
pigs (n=2), morphologically unidentifiable lesions from pigs (n=3),
nonfertile cysts from cattle (n=3) and taeniid eggs from dog faecal
samples (n=34) [5]. Risk factors for cystic echinococcosis were evaluated
by a questionnaire.
Results: CE was prevalent in 13.2% (81/612) of the pigs reared in small
family farms and 4.1% of those reared in industrial farms. Molecular
analysis of isolated taeniid eggs revealed in 10.8% of the dogs
investigated Taenia spp., in 3.8% E. granulosus (G 6/7) and in 0.8%
E. multilocularis. In addition, three samples from livers of human and from
a cow were confirmed as E. granulosus larval stage by PCR. Sequence
analysis confirmed the ‘pig strain’ (G 6/7) in all pig, dog, cattle and
human isolates investigated. No significant risk factor for infections with
E. granulosus or Taenia spp. could be identified.
Conclusion: The ‘pig strain’ of E. granulosus is highly prevalent in the
southwestern part of Lithuania, and transmission is more likely in small
family farms indicating a high exposure to cestode eggs in rural areas.
Therefore control programs should be initiated with special reference to
small family farms.
References
1. Danilevičius E: Cystic echinococcosis and immunodiagnosis in pigs in
Lithuania. PhD thesis. Kaunas 1964, (in Lithuanian).
2. Marcinkutė A, Bareišienė MV, Bružinskaitė R, Šarkūnas M, Tamakauskienė R,
Vėlyvytė D: Cystic echinococcosis in Lithuania. Lithuanian General
Practitioner 2006, 10:8-11.
3. Mathis A, Deplazes P, Eckert J: An improved test system for PCR-based
specific detection of Echinococcus multilocularis eggs. J Helminthol 1996,
70:219-222.
4. Roepstorff A, Nansen P: The epidemiology, diagnosis and control of
helminth parasites of swine. FAO Animal Health Manual 3, Food and
Agriculture Organization of the United Nations 1998, Rome, Italy.
5. Trachsel D, Deplazes P, Mathis A: Identification of taeniid eggs in the
faeces from carnivores based on multiplex PCR using targets in
mitochondrial DNA. Parasitology 2007, 134:911-920.
S15
Sylvatic Trichinella reservoir not found among voles in Finland
Hanna Välimaa1*, Jukka Niemimaa2, Antti Oksanen1, Heikki Henttonen2
1
Finnish Food safety Authority Evira, Fish and Wildlife Health Research Unit
(FINPAR), Oulu, Finland; 2Finnish Forest Research Institute, Vantaa Research
Unit, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S15
Background: Sylvatic Trichinella infection has been found to be very
common in Finnish wild carnivores [1], especially locally in Southern and
partly Central Finland. Cannibalism and carrion feeding have been
regarded as the major source of infection to red foxes and raccoon dogs.
Voles have been found the major food items of red foxes [2]. They are
regarded as herbivorous, but many herbivores consume animal tissues
occasionally. Therefore, voles might be assumed potentially to take part in
Trichinella life cycle in the wild. Microtus spp and Myodes spp have been
found to be infected with Trichinella, e.g. [3]. In Finland, refuse tip rats have
been found to be rather commonly infected with Trichinella spiralis [4].
Material: A total of 1761 bank voles Myodes glareolus, and 138 field voles
Microtus agrestis, trapped on 30 transect sampling locations in Finland. In
addition, also 60 shrews, Sorex spp. accidentally found succumbed in the
traps, were also included in the study. After killing, during dissection, the
right hind leg of each animal was removed and frozen until thawed at
laboratory. Left hind legs were spared for confirmation analyses. Following
thawing, the legs were treated as meat inspection samples according to
Commission Regulation (EC) No 2075/2005 utilizing pepsin-HCl digestion.
Results and discussion: No Trichinella spp larva was found in any of the
samples. Therefore, microtid rodents in Finland cannot be confirmed to
Page 14 of 31
take part of the Trichinella spp life cycle. The opposite cannot be
confirmed, either, as absence of evidence is not equal to evidence of
absence. The predilection sites of Trichinella muscle larvae in microtid
rodents are not well-known. Perhaps the right hind leg is not a good
matrix for Trichinella larvae. In addition, even though the material
consisting of 1899 small mammals may appear large at topical inspection,
the potential impact of microtid rodents on Trichinella transmission
biology is based on the high numbers of animals. The Finnish vole
population fluctuates all the time, but during the peaks there are
estimated to be about 200 000 000 voles in the country.
References
1. Oivanen L: Endemic trichinellosis – experimental and epidemiological
studies. Dissertation 2005, Yliopistopaino, Helsinki.
2. Dell’Arte GL, Laaksonen T, Norrdahl K, Korpimäki E: Variation in the diet
composition of a generalist predator, the red fox, in relation to season
and density of main prey. Acta Oecologica 2007, 31:276-281.
3. Holliman RB, Meade BJ: Native trichinosis in wild rodents in Henrico
County, Virginia. J. Wildl. Dis 1980, 16:205-207.
4. Mikkonen T, Valkama J, Wihlman H, Sukura A: Spatial variation of
Trichinella prevalence in rats in Finnish waste disposal sites. J. Parasitol
2005, 91:210-213.
S16
Aggregation in cattle dung-colonizing insect communities
Richard Wall*, Colin Lee
Veterinary Parasitology & Ecology Group, School of Biological Sciences,
University of Bristol, Woodland Road, Bristol, BS8 1UG, UK
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S16
Background: Ruminant dung is a highly ephemeral, patchily distributed
resource, which is utilized by a diverse community of invertebrate species. This
ecologically important community may be affected adversely by insecticide
and endectocide residues in the faeces of treated cattle. The aim of the
present work was to quantify the aggregation of the insects colonising cowdung in cattle pastures and test the hypothesis that the dung-pat community
assemblage observed is the result of stochastic colonization events.
Methods: Fresh dung from dairy cattle was used to construct arrays of
standardised, 1.5kg, artificial cow pats in cattle pastures. Batches of ten
pats were placed out each week for 24 weeks, between May and October
in 2001. Pats were left exposed in the field for seven days, to allow
colonisation. Pats were then brought back to the laboratory and insect
colonizers were collected and identified.
Results: Individual pats contained on average, only half the number of
insect taxa present in an entire batch put out at any one time. Among six
representative taxa of Diptera and four of Coleoptera, significant levels of
intraspecific aggregation were observed in all but one (Mesembina
meridiana), with the abundance of most taxa within pats approximating a
negative binomial distribution. A simulation analysis was used to show
that the observed relative frequency of taxa within pats does not differ
from that expected by chance if colonisation is a random binomial event
in which each species colonises a pat independently of all other species.
Conclusion: The highly aggregated distributions observed in this study
highlight the need for relatively large sample sizes when attempting to
assess the abundance and distribution of individual taxa in cow dung. In
addition, the results suggest that the aggregated populations of even
highly abundant insects will be more susceptible to the deleterious
effects of insecticidal residues in dung than if they were evenly
distributed, if by chance they colonize a pat containing insecticidal
residues from a recently treated animal.
S17
Important ectoparasites of Alpaca (Vicugna pacos)
Set Bornstein
Dep. of Virology, Immunobiology and Parasitology, National Veterinary
Institute, Uppsala, Sweden
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S17
Summary: Background: Alpacas (Vicugna pacos), earlier named Lama
pacos, belong to the family Camelidae of which there are 7 living
species. Four are native to South America and of those four two are
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domestic species, the alpaca (Vicugna pacos) and the llama (Lama
glama) and two are wild, the vicuña (Vicugna vicugna) and the guanaco
(Lama guanicoe). These species are often referred to as the New World
camels (NWCs) or the South American Camels (SACs) [1]. To the three
Old World camels (OWCs) belong the bactrians or the two-humped
camel (Camelus bactrianus). Lately it has been established that there are
two different species of bactrians, one domesticated and one wild
endangered species [2]. The latter lives on the border between
Mongolia and China. The other domesticated OWC species is the more
well known, the one-humped or the dromedary camel (Camelus
dromedarius).
The Camelidae evolved and developed parallel to the Ruminantiae over
35 million years ago in North America [1] and have developed special
anatomical and physiological features which are of great significance to
their biology, well adapted to the extreme climatic environments of the
rough countries of deserts and semi-deserts of Asia, the Middle East and
Northern Africa (OWC) and the high altitude country of the Andes in
South America (SAC/NWC), respectively. The Camelidae (long neck and
small head) are members of the order of Artiodactyla (even number of
digits), suborder Tylopoda (modified ruminants with pad or callus on
each foot).
All camelids have 37 pairs of chromosomes and the karyotypes are quite
similar. The SACs can interbreed and produce fertile offspring.
Page 15 of 31
Important livestock: The alpacas as well as the llamas were and still are
very important livestock in large areas of South America, particularly in
Peru, Bolivia, Ecuador, Chile and Argentina ([3,4,1]. Since the llamas and
alpacas were domesticated about 4-5000 BC [1], they have been the most
important resource of human culture and survival in the high altitude
environments of the Andes. The SACs are better adapted than any other
domesticated species to the very cold, hard and fragile areas with very
low oxygen pressure (altitudes between 4-5000m).
Alpaca provide meat, hides, fuel, manure and particularly very fine fibres
(wool), which are highly priced. Today more than 500,000 peasant
families are raising SACs in the Andes and these livestock are the main
source of income for the campesinos. Increasing numbers of alpaca are
being imported to various countries outside of South America including
Europe for wool production, breeding and as companion animals. This is
a fairly recent phenomenon that started with larger exports from Chile in
1983-84, first to North America [1].
Ectoparasites: The alpacas as other livestock are exposed to and affected
by a range of ectoparasites (see Table 1). Of particular importance are the
mange mites, the burrowing Sarcoptes scabiei and the non-burrowing
Chorioptes sp and Psoroptes sp and lice, both biting and sucking
Phthiraptera. The mange mites have been reported to be common
infestations on alpacas also in countries outside of South America.
Problems with mange are reported frequently from several countries in
Table 1 (abstract S17) Ectoparasites of alpaca belonging to the Phylum, Arthropoda
Order
Family
Species
Astigmata
Sarcoptidae
Sarcoptes scabiei
sarcoptic mange
Psoroptidae
Chorioptes sp
chorioptic mange
Psoroptes sp
psoroptic mange (ear canker)
Demodex sp
demodectic mange
Otobius mengnini
otitis
Ixodes holocyclus
Tick paralysis
Dermacentor spp
Tick toxicosis
Prostigmata
Demodicidae
Metastigmata
Argasida (Soft ticks)
Disease
Ixodidae (Hard ticks)1
2
Phthiraptera
Sucking lice
Biting lice3
Microthoracius spp
Bovicola (Damalinia) brevis
Siphonaptera
Flees
Vermipsylla sp
Diptera (flies)
Culicidae (mosquitos)
Simulidae (black flies)
Tabanidae
Tabanus spp (horse flies, deer fly)
Muscidae
Musca domestica (house fly)
M autumnalis (face fly)
Stomoxys calcitrans (biting stable fly)
Hydrotea spp
Haematobia spp
Sarcophagidae
Calliphoridae
(blowflies)
Calliphora sp
Cochliomyia hominivorax (primary screw worm)
Phaenicia spp (green blow fly)
Phormia spp (black blow fly)
Oestridae (Bot flies)
Oestrus sp
Cephenomyia sp
1
2
3
Alpacas are at risk to be infested by native ticks e.g. in Scandinavia by various Ixodes and Haemophysalis spp, many that are known vectors of pathogens
Suborder; Anoplura
Suborder; Mallophaga
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Europe [5-10]. In the UK e.g. 23 % of alpaca owners were concerned [8]
and in Switzerland alpaca owners regarded mange as one of the four
most frequent health problems [11]. Sarcoptes scabiei var aucheniae is
very prevalent in alpacas as well as in other SACs [3]. It is said to be
responsible for 95 % of all losses due to ectoparasites in alpacas [12,13].
Infestations with Chorioptes sp are also very common. Some regard
Chorioptes mites as the most common ectoparasite infesting SACs [14].
The mite is assumed to be C bovis [15,16]. Psoroptes (aucheniae) ovis may
also be found to infest particularly the earlaps (pinna) and the outer ear
canals, but can also be found elsewhere on the body of alpacas. Mixed
infections occur with two and even three of the mite species [9,17,16].
Mange: Sarcoptic mange: The early acute manifestation of sarcoptic
mange include mild to severe pruritus with erythema, papules and
pustules, developing soon to crusting, alopecia and lichenification and
thickening of the skin (hyperkeratosis), the chronic stage. Lesions may be
seen on the limbs (often between the toes), medial thighs, ventral
abdomen, chest, axilla, perineum, prepuce, the head including the lips
and ears. Fibre-free areas are said to be more often affected. Damage to
the fibre and loss of condition occur. In very severe infections the disease
may result in death [3,17]. There are historical accounts of large
epidemics of S scabiei var aucheniae affecting SACs in South America
(1544, 1545, 1548, 1826, 1836 and 1839) causing havoc in SACs with
mortalities of over two thirds of the populations [3].
Prevalence of the infection among the alpaca of peasant communities in
the Andes is between 20-40 % [12]. The earlier high prevalence of the
infection also seen in the alpacas imported and bred in USA has been
substantially reduced, most probably due to the frequent use of
ivermectin [18]. In Europe there are several case reports [11,17,10], but no
proper study addressing the prevalence of sarcoptic mange infections.
A concern is that S scabiei has a zoonotic potential and that some
variants are not host-specific.
Chorioptic mange: Previously Chorioptes sp infestations were considered
relatively rare in SACs [18,15], although Cremers [19] was of the opposite
opinion. Today chorioptic mange is a very common condition in many
herds worldwide [14,20].
Clinical signs of chorioptic mange may mimic sarcoptic mange, but
animals affected usually exhibit a milder pruritus and sometimes none at
all (subclinical). Individuals with a heavy infestation may be free of any
symptoms of mange although others in the same herd with lower
infestations may show severe extensive skin lesions [20]. Often alopecia
and scaling are seen on the feet – often as in sarcoptic mange between
the toes and the base of the tail. Lesions may spread to the ventral
abdomen, medial limbs and often the ears.
Psoroptic mange: Psoroptic mange is often seen at predilection sites;
pinna and outer ear canals, as erythema, crusting, papules serum
exudates and alopecia. Pruritus is evident emanating from these lesions.
Typical lesions seen in the outer ear canals are big flakes. Pus
occasionally appears which is most likely due to secondary infections.
Ears and parotid regions may become grossly swollen in severe lesions
[3]. However, lesions may be generalised as well as pruritus with or
without involvement of the outer ear canal. Other sites with lesions
reported include; nares, axillae, groin, neck and legs, abdomen, perineum,
shoulders, back and its sides and the base of the tail [16]. Intermittent
bilateral ear twitching and short-duration head shaking may indicate
otitis due to Psoroptes sp infestations [6].
The Psoroptes sp of alpacas and llamas have previously been referred to as
P auchenia or P communis auchinae [6], but adequate identifications of the
different isolates of the mites have not yet been done. There is a concern
that the Psoroptes sp isolated from SACs, referred to as P communis, the
cosmopolitan ear mite of many herbivores [21], might be able to infest
sheep and cattle i.e act as reservoirs for the very serious sheep scab.
Psoroptic mange was reported recently in two alpacas in the UK [13]. One
of the animals came from Chile and the other was born in the UK.
Cross-transmission: The possibility of cross-transmission of any of the
other mange mites and other ectoparasites of alpacas to domestic sheep
and other livestock and vice versa is a concern and, to my knowledge,
has not yet been sufficiently investigated. Sarcoptes scabiei var aucheniae
was reported to be able to infect sheep and horses [22]. Another
Sarcoptes scabiei variant (var. cameli), a common pathogen in
dromedaries, was shown experimentally to be able to infect sheep and
goats [23], and S scabiei derived from goats and sheep readily infected
dromedaries experimentally [24].
Page 16 of 31
Some variants of S scabiei are known to cross-infect humans resulting in
pseudo-scabies. Successful experimental infections of humans with
Sarcoptes scabiei from alpacas have been reported [16,25]. Some authors
do recognize that S scabiei var aucheniae should be regarded as zoonotic
[16].
Diagnosis: The above highlights the importance of correct diagnosis. For
all three mite species apply the same traditional skin scraping
procedures, particularly deep skin scrapings for the burrowing Sarcoptes
mites with microscopic identification of the species. In relatively acute
infections the mites may be difficult to find. Multiple skin scrapings,
employing a blunted scalpel blade often coated with liquid paraffin, are
necessary to make on the same individual and on several animals in
the affected herd, preferably on all animals. The thickly crusted parts
of chronic lesions often yield high numbers of sarcoptic mites.
Recommended procedures of taking skin scrapings and the following
analytical procedures vary [14]. Often the recommendations are to place
the skin scrapings on a glass slide and mix it either with a drop or two of
the solution of potassium hydroxide (NaOH) followed by applying heat
for a few minutes or mix the skin scraping material with liquid paraffin,
followed by applying a glass cover slip. This is then examined for the
presence of ectoparasites under low power.
Another laboratory procedure is to place the scrapings (scabs and debris)
preferably in centrifuge tubes allowing the material to be soaked in a
10 % solution of potassium hydroxide and place the mix in a water bath
(370C) for a few hours after which the material is centrifuged at about
3000 r.p.m. Then the supernatant is discarded and the sediment
examined in a microscope under low power after having added 1-2
drops of glycerine to the sediment.
One can often short-cut above procedure by first examining the collected
skin scrapings in a small petri-dish which is left in room temperature or
< 350C for an hour or two followed by examining the scrapings under low
magnification (stereo-microscope). The raised temperature (> +180C) will
stimulate any live ectoparasite present to move enhancing the possibility
of detecting parasites which then may be isolated and identified. If no
ectoparasite is found the previous described procedures follow.
In regards to Chorioptes sp animals may harbour a relatively low level of
infestation showing no clinical disease, while other individuals may
experience a hypersensitivity reaction with moderate to severe skin
lesions including pruritis, similar to a clinical reaction to acute S scabiei
infections. A recommended site for performing skin scrapings in search of
Chorioptes sp is the dorsal interdigital (between the toes) and axillae
areas [14].
Low power microscopical examination of material from superficial skin
scrapings and swabs rubbed into the outer ear canal may identify
Psoroptes sp. For proper identification isolates should be sent to experts
in the field.
When diagnosis is not conclusive skin biopsies are recommended in skin
disease. Mites are seldom seen in acute cases in histological sections of
the skin. However, in cases of chronic sarcoptic mange, S scabiei may
often be seen in the epidermis.
Differential diagnosis: Any pruritic dermatitis may mimic infections/
infestations by mange mites There are several other causes of skin lesions
which should be mentioned as differential diagnostic possibilities apart
from dermatitis of bacterial, viral and fungal etiology; e.g. immune
mediated skin disease, hypersensitivity reactions, pemphigus like
conditions, nutritional/metabolic disease, idiopathic hyperkeratosis,
mineral deficiencies i.e. zinc responsive dermatosis. Unfortunately the
latter diagnosis (zinc responsive dermatosis) has become a very popular
diagnosis that is seldom proven correct.
Phthiriosis (lice): Bovicola (Lepikentron) breviceps Rudow, 1866 (the biting
or more appropriate the chewing louse), varying in size from 0.5x1.2 mm
to 1.5x4 mm, is more common in llamas than in alpacas. The colour of
the body of the louse is white or light tan and it has a blunt broad head
that is distinctly different from the elongated mouthparts of the sucking
lice. Infestations are mostly seen on the dorsal midline, base of the tail,
on the side of the neck and along the sides of the body.
Clinical signs of infestations are often a lack of lustre and a ragged
looking coat. Infested animals exhibit pruritus. Heavy infestations result in
matting and loss of fibres [15], but do not seem to have negative effects
on the quality of the fibres or pose any health risk to alpacas [26].
Alpacas are more often infested with the sucking lice, Michrothoracius
mazzai Werneck 1932 characterized by its elongated spindle-shaped
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head, which is almost as long as its abdomen. Earlier in the literature the
former species has been misnamed M prealongiceps [27]. Preferred sites
of attachment are around the flanks, head, neck and withers. Although
these lice are large enough to be seen with the naked eye, about two
thirds the size of the biting lice, they are often partly imbedded in the
skin taking a blood meal and thus may be difficult to see.
Clinical signs are pruritus, restlessness, hair loss and poor growth. Severe
infestations can cause anaemia. The biting lice may be found by parting
the fibres down to the skin using a bright light in search of tiny moving
specks. Nits (eggs) may be seen attached to the fibres. The smaller
sucking lice can be seen clinging to the fibres close to the skin or
imbedded in it.
Treatment: A variety of insecticides and acaricides have been used on
SACs with varying levels of success. In the past there have been several
substances and dosage regimes employed to treat mange mites. The
Peruvian Indian peasants believed that the fat of condors was a good
cure. This practice was later replaced by used motor oil [3]. Relatively few
of the commonly used acaricidal substances and insecticides have been
scientifically tested on SACs. The modern macrocyclic lactones e.g. have
been tried but not undergone proper testing for efficacy or safety on
these animals that have such a unique physiology and metabolism
compared to other domestic species. Pharmacokinetic studies of
macrocyclic lactones as well as other well known therapeutic products
are limited in SACs [28,29]. As yet there are few if any therapeutic
products available licenced for these particular animals. This forces the
clinicians to use off-label products licenced for other production animals,
mostly ruminants. However, several well known therapeutic substances
not licensed for use on camelids have been and are used on SACs, some
with good results.
A number of authors have used ivermectin at 200 µg/kg by subcutaneous
injection with variable but often good results against mange mite
infestations and sucking lice in SACs [15,16]. Some have employed higher
doses e.g. 400 µg/kg and with more frequent applications (even weekly)
than the recommended standard dosages used for other livestock. Also
topical use of products containing eprinomectin, doramectin and
moxidectin have proved efficacious in some treatments, but not in others
[16,10]. Applying injectibles (systemic therapy) in combination with
topical treatments is often required to get better results [30]. Particularly
patients with chronic lesions with thickened crusty hyperkeratotic skin
need to be treated aggressively. In addition, perhaps an earlier
recommendation to employ hand-dressing (with a brush) of the thick
hyperkeratotic areas of the skin with tepid water with soap and
keratolytic agents (e.g. salicylic acid solutions) would shorten the recovery
time and reduce the amount of acaricides used [31,32].
Chorioptes sp infestations have often showed to be difficult to control and
eradicate [9]. Also Sarcoptes scabiei infections have been very difficult to
successfully treat [17]. Whether ``fomites`` play any significant role in
regards to re-infection/infestation is debatable. Sarcoptes scabiei outside
their host will not survive more than about three weeks. However,
Chorioptes spp may survive for a little more than 60 days.
The fibres of alpacas do not contain lanolin which is necessary for the
effective spreading of topically applied products, i.e. pour-ons,
formulations designed for other livestock than camelids e.g. cattle and
small stock. This may partly explain therapeutic failures on alpacas [6].
When using pour-ons it is essential to apply the products direct on the
skin.
There are numerous insecticides including pyrethrins, chlorinated
hydrocarbons, carbamates and organic phosphates which may eradicate
lice, but the problem is the administration of the products. The clue to
successful treatment is to establish contact with the parasites. Lice
infestations are easier to treat than the above mentioned mange mites.
Ivermectin at a dose rate of 200µg/kg body weight administered
subcutaneously is effective against sucking lice [15], but not against the
biting or chewing lice. Cypermethrin at a dose rate of 10 mg/kg has been
used with good effect [33,34]. A single treatment is thought to be
enough but two treatments 14 days apart is recommended as back-up
[33]. Eradication of infestations require repeated treatments and isolation
until the animals are found to be completely free of the parasites [33].
The results of several case reports indicate the need to treat more
frequently and with higher dosages of some of the acaricidal substances
used, compared to the formula for ruminants [16]. It is vital to closely
monitor the results of treatment i.e. the clinical resolution following the
Page 17 of 31
therapies employed before deciding on whether to stop treatment or
change the regimen. Successful treatment should be followed by
effective biosecurity measures to prevent the risk of re-infection/
infestations. In addition it is recommended to treat all the animals in the
herd at the same time.
Acknowledgement: The author is grateful to Mrs Anita Lilburn for
valuable linguistic revision of the manuscript and to Dr Aiden P Foster for
letting me use valuable images of his case material.
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S18
Coccidiosis in farmed silver foxes (Vulpes vulpes) and blue foxes (Alopex
lagopus) in Finland: a case report:
Tapio Juokslahti1*, Teija Korhonen2, Antti Oksanen3
1
Helsinki University, Faculty of Veterinary Medicine (Docent), Helsinki, Finland;
2
Finnish Food safety Authority Evira, Production Animal Health Research
Unit, Seinäjoki, Finland; 3Finnish Food safety Authority Evira, Fish and Wildlife
Health Research Unit (FINPAR), Oulu, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S18
Summary: Fur animal farming was initiated during the 1890s on Prince
Edward Island in Canada. Farmed silver foxes descend from animals caught
from the wild on the island. Finnish fur farming increased during the post war
period and in mid-1980s, there were about 6000 fur animal farms, mostly
located in Southern Ostrobothnia (Fig.), producing about 8 million fur animals
yearly. Currently, there are approximately 1300 fur farms and the yearly
production in 2007 was about 2 million fox and 2 million mink furs. The global
production at the same time was about 7 million fox and 58 million mink furs.
An outbreak of clinical enteric coccidiosis was encountered at a fox farm
with silver foxes (Vulpes vulpes) and blue foxes (Alopex lagopus) in
intensive farming district of Osthrobothnia in Finland during summer
2008. The breeding animal stock of the farm consists of 1500 silver fox
females and 4000 blue fox females. The whelping period of the silver
foxes was from April 20 to May 25, and the whelping period of the blue
foxes was from ay 5 to June 10.
The first clinical signs were seen on silver fox whelps at the age of three
weeks. The whelps were unthrifty, their stools were watery, and they
littered the floors of the wooden whelping boxes. Their fur was moist and
clamped. The females also had moist fur coat, which clamped in the
cervical and abdominal areas. There was not increased mortality. The
morbidity was about 50 %, with all the whelps in affected culls showing
the symptoms. At this time the females are still nursing their whelps, and
the whelps keep themselves mostly inside the whelping boxes. After these
first symptoms, all whelps were studied clinically. They showed marked
unthriftyness and poor growth. The body size of the animals was
significantly smaller than the normal at this age. Affected whelps were
submitted to post-mortem examination to Finnish Food Safety Authority
Evira laboratory in Seinäjoki. In parasitological flotation test from intestinal
contents, coccidian oocysts were detected. Faecal samples were submitted
for quantitative parasitological analysis and species identification.
Of the six silver fox whelp faecal samples, coccidian oocysts were found
in 4; max 5600 oocysts per gram (opg), and of the four blue fox whelp
faeces, oocysts were found in two, max 120 opg. Two species of Isospora
were found. Oocysts of the first one were 30-37x24-28 µm (mean [n=20]
35.3 (SD 0.9) x 26.2 (SD 0.4) µm, and sporocysts measured 15-16x14-15
µm (mean [n=20] 15.5 (SD 0.2) x 14.8 (SD 0.5). Sporozoites measured
within sporocysts within oocysts were about 13x5 µm (cannot be
Page 18 of 31
measured very accurately). The oocyst surface is colourless, smooth and
clear. There is neither Stieda body nor micropyle in the oocyst or
sporocyst. No oocyst granule, but sporocyst residuum sometimes present.
This species was identified as Isospora canivelocis (Weidman, 1915)
Wenyon, 1923. Duszynski et al. [1] consider it possible that this species is
identical with Isospora buriatica Yakimoff and Matschoulsky, 1940 in
Matschoulsky, 1941 from the Corsac fox and Indian fox, and, more
interestingly, with Isospora canis Nemeseri, 1959 from the domestic dog.
The other species oocysts measured 21-26x16-21 µm (mean [n=10] 23.4
(SD=1.2) x 18.4 (SD=1.0) µm, and sporocysts measured 11-13x10-13 µm
(mean [n=10] 12.2 (SD=1.0) x 11.4 (SD=1.0). The oocyst of this species is
slightly smaller but essentially indistinguishable from Isospora ohioensis
Dubey, 1975, which was described to be 24x21 (21-27x19-23) µm in size.
Variation in oocyst size can be caused by e.g crowding in heavy
infections. Also the infection phase can affect oocyst size.
The animals were treated with oral sulfadiatzine-trimethoprim (ratio 5:1)
medication at a dose of 120 g per ton of semimoist feed for five days, the
effect was variable, but the whelps later gained their normal condition and
started to gain weight. The treatment was judged to be satisfactory.
A second outbreak was observed on the same farm in blue fox whelps,
when they reached the age of three weeks. The symptoms were similar
to that of the silver foxes earlier, but more severe. The mortality was low
also at this outbreak, but morbidity was higher, and the weight
development was more affected. Whelps were submitted to post-mortem
examination, and coccidiosis was confirmed. The affected whelps were
treated with one individual oral dosing of toltrazuril by syringe at 10 mg
per whelp and with oral sulfadiatzine-trimethoprim medication for five
days, similar to the silver fox whelps. The recovery in the blue fox
outbreak was pronounced, and better than that of the silver fox outbreak.
Discussion: The whelps most probably received the infection from their
dams, which are known to shed parasites at puerperal period. Also
horizontal infection within litters in the whelping boxes is to be
considered. The hygienic conditions on the farm deserve attention, and
on this farm they may have contributed to the outbreak.
The farm is located in the intensive fur farming district with proximity to
other fur animal farms. The spread of the parasites within the farm and
possibly also between other farms may have been facilitated by blackheaded gulls (Larus ridibundus), which frequently feed under the cage
nettings and the feeding boards of the foxes. They may be vectors for
the parasite spread with their feet.
Clinical coccidiosis is reported on fur animals [2], clinical case of this
severity is the first one encountered in Finland. From the Internet, it
appears that in Chinese veterinary medical literature, silver fox coccidiosis
is described as a well-known disease and an important problem [3].
This reported outbreak calls for closer examination of the occurrence of
clinical coccidiosis amongst Finnish fox farms, the coccidian species
capable of infecting both blue foxes and silver foxes, and the control
measures of the clinical coccidiosis including potential infection routes,
vehicles, and the therapy.
References
1. Duszynski DW, Couch L, Upton SJ: Coccidia (Eimeriidae) of Canidae and
Felidae. Supported by NSF-PEET DEB 9521687 2000 [http://biology.unm.edu/
biology/coccidia/carniv1.html].
2. Wenzel UD, Berestov VA: Pelztierkrankheiten. VEB Deutscher, Berlin;
1986:98-99.
3. Ping JiXing, Hongyong Wang, Zhou Zhenghong, Zhenchun to: Silver Fox
coccidiosis treatment. Cure of the silver fox Coccidiosis. Poujian through
pathology and laboratory checks to early diagnosis of the Silver Fox
coccidiosis, and to Treatment. Coccidia powder words of the disease
have a better effect, in addition, sanitation is also extremely important.
Hubei Animal Husbandry and Veterinary 2003, 01.
S19
Haemonchosis in a sheep flock in North Finland
Saana-Maaria Manninen*, Antti Oksanen
Finnish Food Safety Authority (FINPAR), Evira Fish and Wildlife Research Unit,
Oulu, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S19
Background: In May 2008 two sheep from a farm in Ylikiiminki (65°N
26°E) were autopsied at Finnish Food Safety Authority Evira in Oulu and
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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diagnosed with a Haemonchus contortus infection. Haemonchus contortus
has a few years ago been reported on the island of Hailuoto just outside
Oulu, where it led to a lethal infection. Although this to sheep highly
pathogenic nematode has been detected in Finland already in 1933 by
Agnes Sjöberg [1], it has apparently never been reported so far up north
in Finland. In Sweden H. contortus has almost reached the Arctic Circle
[2]. It does not survive the Nordic winter on pasture, but with almost 100
% arrested development in the early fourth larval stage it is capable of
surviving the Nordic winter within its host [3].
The farm the infected sheep originated from is a small sheep farm with
also a few goats and other domestic animals such as horses, turkeys and
rabbits. They had bought their first sheep in November 2006, part of the
ewes being pregnant at time of purchase and lambed in January. The
sheep are of Finnish race, Texel-Oxford, Kainuu grey and cross-breeds. In
the winter the sheep are housed in an approximately 150 m2 barn with
thick straw bedding and access to a corral sized about 500 m2. Grazing
grounds from May until snowfall (in October) consists of approximately
4 ha of pasture and 1 ha of mixed forest. According to the owner the
totally about 35 sheep and 4 goats mainly used the pasture grass as their
nutrition, but were also given hay in round bales, when the feeding area
became very contaminated with faeces. The drinking water was
accessible in the nearby river Kiiminkijoki. The animals were treated with
fenbendazole in the autumn of 2007.
In the spring of 2008 many of the sheep (age 1+) became weak and
developed an oedema under the jaw. Two of these animals (one died and
one shot) were autopsied and the rest of the ones with symptoms were killed
and buried. The autopsy findings included oedema under the jaw, paleness
due to anemia and abomasitis caused by a severe parasite infection.
Materials, methods and results: Contents of the abomasum were rinsed
into 2L of water and a 200 mL sample was collected, the adult worms
collected, counted and identified. In one of the sheep 300 abomasal
nematodes were found, where of 90 % were identified as Haemonchus
contortus, the rest being Teladorsagia circumcincta. In the faecal flotation
using a modified McMaster method an egg count (epg) of 5880 was
counted and eggs identified as Trichostrongylidae spp. The other animal
had a more severe infection, and approximately 1600 adult worms were
found in the abomasum, also with 90 % H. contortus and 10 %
T. circumcincta. The results of the faecal egg count for this individual
were following: Trichostrongylidae spp. 36 000 EPG, Strongyloides sp. 400
epg and Eimeria sp. 2040 oocysts per gram faeces.
Discussion: The results indicate that Haemonchus contortus is becoming
a potential threat to sheep in North Finland and the distribution of the
nematode should be monitored. The parasite is hereby proven to cause
very severe disease in the North Ostrobothnian sheep production.
Considering the effects of the climate change, that can be very
affirmative for H. contortus life cycle, and the increasing amount of sheep
in North Finland [4], the occurrence of this parasite in these latitudes
should not be left without attention. Moreover, it may be transmitted to
other species such as reindeer [5]. In case of an infection with H.
contortus, the flock could be recommended treatment with a macrocyclic
lactone antoparasitics, as eradication of the parasite on an individual farm
possible with correct administration of anthelmintics in the winterperiod
when the animals are housed [6].
References
1. Sjöberg-Klaavu A: Om nematoder i matsältningsorganen hos får i
Finland. [About nematodes in the gastrointestinal tract in sheep in
Finland]. In 4. Nordiska veterinärmötet, section IX Helsingfors, Tilgmanns
tryckeri, (In Swedish).
2. Lindqvist Å, Ljungström B-L, Nilsson O, Waller PJ: The dynamics,
prevalence and impact of nematode infections in organically raised
sheep in Sweden. Acta vet. scand 2001, 42:377-389.
3. Waller PJ, Rudby-Martin L, Ljungström BL, Rydzik A: The epidemiology of
abomasal nematodes of sheep in Sweden, with particular reference to
over-winter survival strategies. Veterinary Parasitology 2004, 122:207-220.
4. TE-keskus: Statistics. 2008, Available online: http://www.te-keskus.fi/Public/
download. [Accessed 20. July 2008].
5. Hrabok JT, Oksanen A, Nieminen M, Rydzik A, Uggla A, Waller PJ: Reindeer
as hosts for nematode parasites in sheep and cattle. Veterinary
Parasitology 2006, 136:297-306.
6. Waller PJ, Rydzik A, Ljungström BL, Törnquist M: Towards the eradication
of Haemonchus contortus from sheep flocks in Sweden. Veterinary
Parasitology 2006, 136:367-372.
Page 19 of 31
S20
Comparative evaluation of efficiency of traditional McMaster chamber
and newly designed chamber for the enumeration of nematode eggs
Asta Pereckiene1*, Saulius Petkevicius1,2, Antanas Vysniauskas1
1
Veterinary Institute of Lithuanian Veterinary Academy, Instituto 2, LT-56115
Kaisiadorys, Lithuania; 2Department of Infectious Diseases, Lithuanian
Veterinary Academy, Tilzes 18, LT-47181 Kaunas, Lithuania
E-mail: [email protected]
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S20
Summary: The objective of this study was to perform the comparative
evaluation of efficiency of traditional McMaster chamber and the newly
designed chamber for the enumeration of nematode eggs in different
agriculture animals. Thirteen pig, two horse and two sheep farms were
randomly selected, and 815 of pig faecal samples, 264 of horse and 264
of sheep faecal samples were examined. The positive samples were
identified by Henriksen and Aagaard (1976) [1] modification of McMaster
method. Furthermore, experimental horse faeces were examined by [1]
and Urquhart et al., 1996) [2] modifications, whereas pig and sheep
faeces were examined by [1] and Kassai, 1999 [3] modifications,
respectively. All samples were evaluated in two replicates: using
traditional McMaster 0.3 ml chamber – I and newly designed 1.5 ml
chamber – II [4]. In pig farms, 11.5% and 18.2% (chambers I and II,
P<0.05) of pigs were found infected with Ascaris suum. Furthermore,
14.6% and 17.8% (chambers I and II, P<0.05) of pigs were found infected
with Oesophagostomum dentatum and 3.7% and 8.2% (chambers I and II,
P<0.05) with Trichuris suis, respectively. In horse farms, 65.5% and 83.7%
horses infected with strongyles were identified (chambers I and II, P<0.05.
In sheep farms, the number animals of positive to strongyle infection was
81.4% and 96.2% (I and II chambers, P<0.05). The new modification of
chamber [4] demonstrated statistically higher sensitivity for enumeration
of nematode eggs and for evaluation of farms with infected animals
compared to McMaster modifications described in [1-3].
Introduction: Faecal examination is an important tool for monitoring
worm infections in farm animals and an important adjunct to maintaining
effective worm control programmes. Described faecal examination
methods are either qualitative or quantitative. Qualitative methods
provide information on the species present, whereas quantitative
methods provide an indication of the levels of infections. Both have their
own importance in determining the health status of a herd and
determining appropriate treatments and control measures. Quantitative
examinations are performed by different modifications of the McMaster
method, which is the most widely used and standard quantitative
technique with sensitivity from 10 to 100 eggs per 1 g of faeces [5-15].
Furthermore, the following chambers are used for egg count: traditional
McMaster chamber with two chambers (2 x 0.15 ml), Gordon-Whitlock
chamber (3 x 0.15), Whitlock McMaster chamber (3 x 0.3 ml), Whitlock
universal chamber (4 x 0.5 ml), FECPAK 1 ml chamber (2 x 0.5 ml), and
modified MAFF 1 ml chamber (2 x 0.5 ml) [5,7,16-19].
We produced a new type of chamber and tested it by the high
performance modification of McMaster method using the highest
possible amount of faeces and reducing the sensitivity coefficient. The
new chamber was compared with the traditional McMaster chamber in
both cases using the McMaster method modifications [1-3]. The
traditional (I) and the new chambers (II) were used for comparative
analysis to evaluate the performance and stability of faecal examination
results.
Materials and methods: Thirteen pig, two horse and two sheep farms
were randomly selected, and 815 of pig faecal samples, 264 of horse and
264 of sheep faecal samples were examined. The positive samples were
identified by [1] modification of McMaster method. Experimental horse
faeces were examined by [1] and [2] modifications, whereas pig and
sheep faeces were examined by [1] and [3] modifications, respectively. All
samples were evaluated in two replicates: using traditional McMaster
0.3 ml chamber – I, and newly designed 1.5 ml chamber - II [4]. The new
egg count chamber (II) has a bead, which prevents the faeces suspension
from seeping out and protects the optics of microscope from adverse
effect. Comparisons were made as to the number of samples found to be
positive by each of the chamber.
Results: Ascaris suum infection was identified in all investigated pig
farms, but the number of infected pigs estimated with the two chambers
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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was significantly different − 11.5% (94/815) of pigs positive (chamber I)
and 18.2% (148/815) of pigs positive (chamber II). Whipworm infection
was identified only in 8 farms (chamber I) and in 11 farms (chamber II) −
3.7% (30/815) and 8.2% (67/815) of samples were positive to T. suis
infection. Nodular worm infection was identified in 5 and 7 farms
(chambers I and II) − 14.6% (119/815) and 17.8% (145/815) of positive
pigs, respectively. The number of positive samples (chamber II) to Ascaris
suum was on 1.6, Oesophagostomum dentatum on 1.2, and Trichuris suis
on 2.2 times higher compared results with chamber I. In farms where up
to 10% of samples were identified as infected with chamber I, the
difference coefficient was highest (1.8). However, in the farms where
>50% of infected pigs were identified with chamber I, the difference
coefficient was lowest (1.02).
In horse farms, 65.5% (173/264) and 83.7% (221/264) of horses were
identified infected with strongyles (chambers I and II, P<0.05). The number
of samples positive to Strongylus spp. was on 1.2 times and to Parascaris
equorum on 3.4 times higher with chamber II compared to chamber I. In
sheep farms, the number of animals positive to strongyle infection was
81.4% (215/264) and 96.2% (254/264) (I and II chambers, P<0.05). The
number of samples identified as infected with Trichostrongylus spp. was 1.3
times higher for chamber II compared to chamber I, 3.1 times higher for
Toxocara vitulorum, 2.5 times higher for Nematodirus filicollis, and 1.9 times
higher for Trichuris ovis, respectively.
Conclusion: The experimental examination of pig, horse and sheep faeces
using the new 1.5 ml chamber (II) helped to identify a higher percentage of
infected animals compared to the traditional McMaster 0.3 ml chamber (I).
The new modification of chamber [4] demonstrated statistically higher
sensitivity for enumeration of nematode eggs and for evaluation of farms
with infected animals compared to McMaster modifications desribed in [1-3].
References
1. Henriksen SA, Aagaard KA: A simple flotation and McMaster method. Nord
Vet. Med 1976, 28:392-397.
2. Urquhart GM, Armour J, Duncan JL, Dunn AM, Jennings FW: Veterinary
Parasitology. Blackwell Science Ltd., Oxford, UK; 1996:307.
3. Kassai T: Veterinary Helminthology. Butterworth-Heinemann, Oxford;
1999:260.
4. Vyšniauskas A, Pereckienė A, Kaziūnaitė V: Comparative analysis of
different modifications of McMaster method. Veterinarija ir Zootechnika
2005, 29:61-66, (in Lithuanian).
5. Whitlock HV: Some modifications of the McMaster helminth eggcounting technique and apparatus. J. Counc. Sci. Ind. Res 1948, 21:177-180.
6. MAFF (Ministry of Agriculture, Fisheries and Food): Manual of Veterinary
Parasitological Laboratory Techniques. HMSO, London, 3 1986, 24.
7. Anon : Manual of veterinary parasitological laboratory techniques.
Ministry of Agriculture 3rd edition. 1986, 24-25.
8. Coles GC, Bauer C, Borgsteede FHM, Geerts S, Taylor MA, Waller P, Wold J:
Assotiation for the Advancement of Veterinary Parasitology (W.A.A.V.P.)
methods for the detection of anthelmintic resistance in nematodes of
veterinary importance. Vet. Parasitol 1992, 44:35-44.
9. Ihler CF, Bjørn H: Use of two in vitro methods for the detection of
benzimidazole resistance in equine small strongyles (Cyatostoma spp.).
Vet. Parasitol 1996, 65:117-125.
10. Ward MP, Lyndal-Murphy M, Baldock FC: Evaluation of a composite
method for counting helminth eggs in cattle faeces. Vet Parasitol 1997,
73:186-187.
11. Roepstorff A, Nansen P: A Simple McMaster technique. Epidemiology,
diagnosis and control of helminth parasites of swine. FAO. Animal Health
Manual. Rome, Italy; 1998:47-56.
12. Craven J, Bjørn H, Barnes A, Henriksen SA, Nansen P: A comparison of in
vitro tests and a faecal egg count reduction test in detecting
anthelmintic resistance in horse strongyles. Vet. Parasitol 1999, 85:49-59.
13. Varady M, Konigova A, Čorba J: Benzimidazole resistance in equine
cyatostomes in Slovakia. Vet. Parasitol 2000, 94:67-74.
14. Mercier P, Chick B, Alves-Branco F, White CR: Comparative efficacy,
persistent effect, and treatment intervals of anthelmintic pastes. Vet.
Parasitol 2001, 99:29-39.
15. Pook JF, Power ML, Sangster NC, Hodgson JL, Hodgson DR: Evaluation of
tests for anthelmintic resistance in ciathostomes. Vet. Parasitol 2002,
106:331-343.
16. Whitlock HV, Kelly JD, Porter CJ, Griffin DL, Martin ICA: In vitro field
screening for anthelmintic resistance in strongyles of sheep and horses.
Vet. Parasitol 1980, 7:215-232.
Page 20 of 31
17. Lyndal-Murphy M: Anthelmintic resistance in sheep in Australian
standard diagnostic techniques for animal diseases. Edt. Corner L. A.,
Bagust T., J. 1993, 3-9.
18. Cringoli G, Rinaldi L, Veneziano V, Capelli G, Scala A: The influence of
flotation solution, sample dilution and the choice of McMaster slide area
(volume) on the reliability of the McMaster technique in estimating the
faecal egg counts of gastrointestinal strongyles and Dicrocoelium
dentriticum in sheep. Vet. Parasitol 2004, 123:121-131.
19. Presland SL, Morgan ER, Coles GC: Counting nematode eggs in equine
faecal samples. Vet. Rec 2005, 156:208-210.
S21
Metastrongylus spp. infection in a farmed wild boar (Sus scrofa) in
Finland
Paula Syrjälä1*, Antti Oksanen2, Outi Hälli3, Olli Peltoniemi3, Mari Heinonen3
1
Veterinary Bacteriology Research Unit, Finnish Food Safety Authority Evira,
Kuopio, Finland; 2Fish and Wildlife Health Research Unit, Finnish Food Safety
Authority Evira, Oulu, Finland; 3Department of Production Animal Health,
University of Helsinki, Pohjoinen pikatie 800, 04930 Saarentaus, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S21
Summary: Metastrongylus spp. (Nematoda, Metastrongylidae) are lung
worms of swine and occur worldwide. Species in the family include
M. apri, M. pudendotectus, M. asymmetricus, and M. salmi. Earth worms are
intermediate hosts and pigs get infected when eating earth worms.
In Finland wild boar farming began in the 1980s and now there are over
hundred farms and over 2000 wild boars in different parts of the country.
This case report is part of a study aiming to get more information about
the diseases that occur in the farmed wild boar population in Finland.
Lungworms were detected in an eight month old farmed wild boar sent
for necropsy from a farm situated in eastern Finland. In the group of
25 animals of about the same age, the farmer had noticed poor growth
and gait abnormalities. He submitted two euthanized boars (A and B) for
necropsy. A routine necropsy was performed and tissue samples were
collected for histopathology, bacteriology and parasitology.
The boar A was in a poor nutritional condition. The lungs were slightly
mottled, but otherwise normally inflated. Large numbers of white thread
like nematodes were detected in the bronchi (Fig. 1.). Bones were soft. In
the faecal sample, 7500 EPG Metastrongylus spp. eggs were detected with
flotation (Fig. 2.). The boar B was in a moderate nutritional condition. No
lung worms were detected. The main pathological diagnosis of both was
osteomalacia due to deficiency of mineral feeding. However, the the poor
nutritional condition of the boar A infected with lung worms was possibly
partly due to the lung worm infection. Four additional faecal samples
were sent from remaining boars from the farm and two of them were
also positive for Metastrongylus spp. eggs (100 and 200 EGP).
In Finland Metastrongylus spp. has occurred sporadically in pigs decades
ago in southeastern parts of the country [unpublished, Nikander, [1]. It
Figure 1 (abstract S21) Cross section of Metastrongylus spp. in the lung.
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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Figure 2 (abstract S21) Metastrongylus spp. egg with a larva inside.
was not detected in domestic pigs in a large study done in all Nordic
countries in 1980’s [1]. It was also not found in a study of Danish
organic swine herds [2]. In natural wild boar in many countries this
parasite is common [3-6]. In the modern pig industry this infection
seems to have been disappeared, because there is no contact with the
intermediate host, the earth worms. However, in the farmed wild boar,
and in situations where pigs are kept outdoors, Metastrongylus spp.
should be considered as a possible cause of poor growth and
respiratory signs.
References
1. Roepstorff A, Nilsson O, Oksanen A, Gjerde B, Richter SH, Örtenberg E,
Christensson D, Martinsson KB, Bartlett PC, Nansen P, et al: Intestinal
parasites in swine in the Nordic countries, prevalence and geographical
distribution. Vet Parasitol 1998, 76:305-319.
2. Carstensen L, Vaarts M, Roepstorff A: Helminth infections in Danish
organic swine herds. Vet Parasitol 2002, 106:253-264.
3. Järvis T, Kapel Ch, Moks E, Talvik H, Mägi E: Helminths of wild boar in the
isolated population close to the northern border of its habitat area. Vet
Parasitol 2007, 150:366-369.
4. Morita T, Haruta K, Shibata-Haruta A, Kanda E, Imai S, Ike K: Lung worms of
wild boars in the western region of Tokyo, Japan. J Vet Med Sci 2007,
69:417-420.
5. de-la-Muela N, Hernandez-de-Lujan S, Ferre I: Helminths of wild boar in
Spain. J Wildl Dis 2001, 37:840-843.
6. Barutzki D, Schoierer R, Gothe R: Helminth infections in wild boars in
enclosures in southern Germany: species spectrum and infection
frequency. Tierarztl Prax 1990, 18:529-534.
S22
Rare canine parasites survive in the wild fox population
Marja Isomursu*, Niina Salin, Antti Oksanen
Finnish Food safety Authority Evira, Fish and Wildlife Health Research Unit,
Oulu, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S22
Summary: Members of the canid family – e.g. domestic dog Canis
familiaris, wolf Canis lupus, red fox Vulpes vulpes and raccoon dog
Nyctereutes procyonoides – share a wealth of parasite species. Nowadays,
the diversity of the parasitic fauna of domestic dogs is reduced by
antiparasitic medications and disposal of faeces, but a thriving population
of wild foxes can host even rare parasite species. Finnish Food Safety
Authority Evira, Fish and Wildlife Health Research Unit, examines approx.
250 fox carcasses for zoonoses every year. Some rarely seen canine
endoparasites were observed in the winter 2007-2008.
In January 2008, one of the first Finnish domestic cases of Spirocerca sp.
infection was observed in a fox hunted from North Lapland fjeld area in
Utsjoki (69° N 27°E). The previous one reported was imported from
Tanzania [1]. A 30 x 15 mm granuloma containing two large, red, coiled
Page 21 of 31
nematodes was formed on the curvatura major of the stomach. The fox
was a male individual in good condition.
In a 1.5 year-old female fox from Pyhtää, Southeast Finland, a solitary
female individual of French heartworm Angiostrongylus vasorum was
lodged in the right ventricle, in the opening of the pulmonary artery. The
existence of this parasite in Finland is very inadequately known, but it is
spreading in Europe, e.g. in Denmark [2].
A massive liver fluke Metorchis albidus infection was observed in an aged
(6.5 yrs) female fox from Virolahti, Southeast Finland. The flukes had
caused a severe cholangitis. Although Metorchis is a very occasionally
seen parasite in Finland, it is regarded as common in Germany [3].
In addition to these isolated cases, a small survey of the occurrence of
the bladder hairworm Capillaria plica was conducted in February 2008.
Scrapings of urinary bladder wall were taken from 44 foxes from North
Lapland and 7 of them (16%) were positive for eggs or worms. In a
Danish study, about 80 % of foxes examined were found infected with
this parasite [2]. All four parasite species mentioned above have at least
one intermediate or paratenic host which may facilitate their persistence
in the nature.
It is interesting to notice that a similar amount of raccoon dogs are also
examined and comparable findings to the abovementioned have not
been made. The raccoon dog often harbours higher Trichinella infection
densities than the red fox does, and this has been speculated to be
caused by some innate or acquired cause of immunoincompetence
(unpublished). Therefore, raccoon dogs might be expected to harbour
occasional parasite infections even more commonly than foxes.
References
1. Nikander -S: Sukkulamadon (Spirocera lupi) aiheuttama osteosarkooma
koiran ruokatorvessa. [Oesophageal osteosarcoma associated with
Spirocerca lupi in a dog.]. Suomen Elainlaakarilehti. 1994, 100(3):173-177.
2. Saeed I, Maddox-Hyttel C, Monrad J, Kapel CMO: Helminths of red foxes
(Vulpes vulpes) in Denmark. Veterinary Parasitology. 2006, 139(1/3):168-179.
3. Schuster R, Bonin J, Staubach C, Heidrich R: Liver fluke (Opisthorchiidae)
findings in red foxes (Vulpes vulpes) in the eastern part of the Federal
State Brandenburg, Germany—a contribution to the epidemiology of
opisthorchiidosis, Parasitol. Res 1999, 85:142-146.
S23
Control of livestock ectoparasites with entomopathogenic fungi: a
review
Stephen Abolins, Richard Wall*
Veterinary Parasitology & Ecology Group, School of Biological Sciences,
University of Bristol, Woodland Road, Bristol, BS8 1UG, UK
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S23
The abundance of ectoparasites requires ongoing management and this
is most commonly achieved with insecticides or endectocides. However,
the growth in resistance, the slow rate of development of new actives,
coupled with environmental and health concerns associated with the
continued use of some of the existing neurotoxic insecticides, suggest
that alternative approaches to their management need to be identified.
Here one possible alternative approach, the use of entomopathogenic
biological control agents, is reviewed highlighting the remaining
obstacles that should be overcome to enable their practical application.
S24
Anthelmintic resistance. An overview of the situation in the Nordic
countries
Carl Fredrik Ihler
Department of Companion Animal Clinical Sciences, Norwegian School of
Veterinary Science, P:O 8146, 0030 Dep Oslo, Norway
E-mail: [email protected]
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S24
Introduction: Gastrointestinal nematodes in grazing animals cause major
production losses and represent an animal welfare problem worldwide.
For decades use of anthelmintics has been central in the control
programs of these parasites. This intensive use of anthelmintic drugs has
resulted in problems with resistance to the anthelmintic drugs available
today. Resistance to all classes of broad-spectrum anthelmintics available
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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benzimidazoles (BZ), imidothiazoles-tetrahydropyrines and macrocyclic
lactones has been reported [1].The time from introducing a new class of
anthelmintic drugs until resistance has been detected seems to be less
than 10 years [1]. As time has passed problems of multiresistance to
more than one class has occurred as well. Multiresistant Haemonchus
contortus has become a major threat to the whole small ruminant
industry in part of South Africa and in the South-East of USA [2,3].
At present, resistant nematode populations are detected in all
our naturally grazing species; sheep, goats, cattle and horses [1].
In pigs, resistance to pyrantel, levamisole and benzimidazoles in
Oesophagostumum spp have been detected [4,5].
Development of anthelmintic resistance: Anthelmintic resistance (AR)
is defined by Køhler as genetically transmitted loss of sensitivity of a drug
in worm populations that were previously sensitive to the same drug [6].
In a worm population, alleles coding for resistance will be present as a
result of mutations, also in unexposed populations. Resistance will
develop if there are survival advantages for parasites carrying these
alleles [7]. Treating worms with drugs corresponding to the “resistance”
alleles will give these worms an advantage and the frequency of resistant
worms in the population will increase. The frequency of alleles coding for
resistance at the time of exposure to a drug will be important for the
rate of the development of a resistant population.
The amount of anthelmintic drugs used and thereby the exposure will
influence the development of AR. Therefore, it is important to establish
de-worming strategies that take this into consideration. Parasite control
programs must have a specific aim and the use of drugs must be kept to
a minimum to achieve this aim. For horses a reasonable aim of a parasite
control program would be to eliminate the large strongyles and have the
cyathostomes and Parascaris equorum infestations under control.
The prepatent period of a parasite will be of importance. Species with
short prepatent periods will have more generations during a grazing
season. Frequent anthelmintic treatment will then expose more
generations of these parasites than species with longer generation
intervals. The trichostrongyles in ruminants (prepatent period approx.
3 weeks) and cyathostomes in horses (prepatent period 6-8 weeks) are
examples of short generation interval species. Strongylus vulgaris has,
however, a prepatent period of 6 months. This difference in generation
interval might be the reason why resistance is common in cyathostomes
and has not been reported in S. vulgaris so far.
Parasites in refugia represent the fraction of the worm population not
exposed to the drug when animals are treated. The free living stages of
the parasites are the most important part of the refugia. The higher the
proportion of parasites in refugia the slower the development of
resistance as the selection pressure of the whole population is lower [8,9].
The importance of refugia can be illustrated by looking at the difference
in development of resistance in Australia compared to New Zealand. In
New Zealand, where the climate is wet, up to 75% of the H. contortus
population are larval stages on the pasture [10], which is considerably
higher than in the more dry climate in Australia. In spite of the fact that
the benzimidazoles and levamisole have been used over the same period
of time, the resistance to these drugs was detected much later in New
Zealand [11].
In the Nordic countries parasites which do not overwinter on the pasture,
such as H. contortus, have only a small proportion in refugia and hence
have a greater selection pressure when animals are treated in this period
than in species where larval stages overwinter on pasture.
Selective treatment of animals will also have impact on the refugia. In
horses selective treatment of animals expelling > 200 eggs per gram
when treated in the grazing season has been suggested. This will reduce
the exposed proportion of the population and thus dilute the resistant
alleles in the population. Such strategy will, however, need an egg count
of faeces from every single animal before treatment. This strategy is
widely used in Denmark [12].
Detection of anthelmintic resistance: Different methods, both in vivo
and in vitro methods, have been used to detect and monitor AR. Faecal
egg count reduction test is the most used in vivo method and gives an
estimation of the efficacy of the drug by comparing the egg counts pre
and post treatment. Guidelines for the method are described by Coles et
al. [13]. The accuracy of the method depends on a correlation between
egg counts and worm burdens which is not always present. Nematodes
like Trichostrongylus colubriformis and Ostertagia circumcincta show little
correlation whereas H. contortus show good correlation [14,15].
Page 22 of 31
The controlled test is the most reliable method but is rarely used because
of high costs. This test uses untreated control groups and the parasitized
animals are euthanized about 10 days post treatment and a necropsy is
subsequently preformed.
Different in vitro methods are described. The egg hatch assay (EHA) was
first described by Le Jambre for the detection of BZ- resistance [16].
Modification of the original method is developed by Taylor et al. [17] and
the method is mostly used for the detection of possible BZ resistance in
sheep and horses [18].The larval development assay (LDA) uses the ability
of the anthelmintic to arrest the normal development from eggs to L3
larvae. By observing the proportion of L3 larvae developed in different
concentrations of an anthelmintic, a LC50 value can be determined. In
this assay anthelmintics with different modes of action can be tested at
the same time and it has been useful in surveys of sheep nematodes
[19]. The test has shown to be difficult to use in equine strongyles due to
repeatability problems [20].
A biochemical test for detection of BZ resistance based on reduced
affinity to tubulin has also been introduced [21]. The method requires a
large number of larvae and is therefore unsuitable for field surveys [17].
Molecular based tests are only in use for detection of BZ resistance as the
molecular mechanisms for resistance to tetrahydropyrimidenes and
macrocyclic lactones are not fully understood [18]. The principle of the
diagnosis of resistance relies on a multiple allele specific PCR. The
method has been used for testing ovine trichostrongyles and equine
small strongyles for BZ resistance. The most common mechanism for BZ
resistance in ovine trichostrongyles involves a phenylalanine to tyrosine
mutation located at residue 200 of the isotype 1 beta-tubulin gene [22].
The same polymorphism is described in equine small strongyles [23].
Anthelmintic resistance in gastrointestinal nematodes in the Nordic
countries: AR most likely represents a problem of all Nordic countries
although few studies have been performed in Finland and Iceland
(Oksanen and Sigurdsson, personal communication).
The Danish veterinary parasitologists have been important expanding
our knowledge of AR in the Nordic countries. In the early 90s the
Centre for Experimental Parasitology in Copenhagen, lead by the
enthusiastic Professor Peter Nansen, performed many studies and
research programs in this field involving PhD students from many
countries. The Centre through Dr. Henrik Bjørn, also inspired research
on anthelmintic resistance in Sweden and Norway together with Dr.
Peter Waller.
In Denmark, several studies have been performed on AR in small
ruminants, horses and swine. The first study on resistance in sheep
nematodes in Denmark was published in the early 90s where resistance
to levamisole in Ostertagia circumcincta was described [24]. Later Maingi
et al. [25] reported evidence of BZ, ivermectin and levamisole resistance
in caprine trichostrongyles in a survey from 15 Danish goat herds. Most
other studies concerning AR in sheep nematodes in Denmark have
focused on comparison of different in vitro tests with the faecal egg
count reduction test and to my knowledge no surveys have been
performed to evaluate changes in the resistance situation over the last
10-15 years.
In Sweden there are no published surveys on resistance in small ruminant
nematodes while there is one single report on the situation in Norway
[26]. In this report BZ-resistance was detected in four out of 26 herds.
Resistance in O. circumcincta was found in all 4 herds while resistance in
Nematodirus battus and H. contortus were suspected in one of these
herds.
In swine, Roepstorff et al. [4] confirmed resistance to pyrantel citrate in
Oesophagostomum spp. in Denmark. Later Bjørn et al. [27] confirmed sideresistance between levamisole and pyrantel in the same species. To my
knowledge no studies on AR in swine parasites have been conducted in
the other Nordic countries. The prevalence of resistant Oesophagostomum
spp. is reported from Germany is estimated to 2-3.5 % [5].
No studies concerning resistance in cattle nematodes have so far been
published from the Nordic countries. Worldwide there are however
studies confirming resistance to all three major classes of anthelmintic
drugs in cattle nematodes [1]. Looking at the experience of other
countries, anthelmintic resistance in cattle nematodes might be a threat
to the cattle industry in our countries as well.
Anthelmintic resistance in intestinal parasites of the horse is without
doubt the area where most studies concerning AR are conducted in the
Nordic countries. In Sweden Nilsson et al. [28] reported BZ-resistance in
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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equine small strongyles. Later Bjørn et al. [29] and Ihler [30] published
high prevalence of BZ-resistance in Denmark and Norway.
Pyrantel resistance in small strongyles has also been reported from the
Nordic countries [30-32]. Resistance to macrocyclic lactones in the equine
small strongyles has so far not reported, but there is a worldwide
agreement that it is just a question of time before this will occur.
However, reports on resistance to ivermectin in the equine roundworm
P. equorum have been published. From Denmark Schougaard and Nielsen
[33] have reported reduced efficacy of ivermectin as have Lindgren et al.
from Sweden [34]. Resistance to ivermectin in the equine roundworm is
suspected in Norway, but a proper study on this has not been conducted yet.
Although most reports on AR in nematodes concern anthelmintics to
ruminant and horse parasites, there are also reports of resistance in the
canine hookworm Ancylostoma caninum to pyrantel [35,36]. No reports in
the Nordic countries on resistance to canine nematodes have been
published.
Reducing the development of AR: AR is a major problem when
controlling parasite infections in production animals and horses
worldwide. As documented, the reason for development of resistance to
anthelmintics is a selection of resistant individuals in the worm
population as a result of anthelmintic exposure. Therefore, efforts to
reduce this exposure will slow down further development of resistance
but will not reverse the existing resistance in a population. The most
obvious way to reduce the exposure is to reduce the use of anthelmintic
drugs and look to other ways to control parasites beside anthelmintic
use.
As no new broad-spectrum anthelmintic drugs with new modes of action
have been introduced since the macrocyclic lactones in the 80s, it is
necessary to take the warnings of AR as a major problem seriously.
Improvement of the grazing management is important in reducing the
use of anthelmintics. Reduction of the stocking rate, reducing the grazing
season on the pastures and mixed grazing between animal species are all
key factors. Furthermore, the animals have to be treated at times when
the effect of treatment is best and underdosing is to be avoided.
Biological control of nematodes is an interesting way of reducing the use
of anthelmintic drugs. The principle of biological control is the use of the
natural enemies of the nematodes to reduce the infection level on
pastures [37]. These methods have no intention of eliminating the free
living larval stages but aim to reduce them to a level where no clinical or
subclinical effects are present while stimulating an acquired immune
response. Nematode destroying fungi have been a potential candidate in
biological control and the fungus Duddingtonia flagrans has shown to be
effective through several studies [38-41]. Most studies on the effect of
feeding D. flagrans have been based on daily intake of the fungi through
feed supplementation. Mineral blocks containing fungal spores or slowrelease devices might be practical ways of feeding the fungal material in
the future and make the method practical in commercial farming.
Development of effective vaccines against intestinal parasites will allow
the opportunity to reduce the use of antiparasitic drugs. In spite of great
efforts making vaccines protecting grazing animals against helminth
infections, only a vaccine against the bovine lungworm Dictyocaulus
viviparus is commercially available [42]
How to deal with the challenge of AR in the Nordic countries:
Keeping in mind that new classes of anthelmintic drugs with different
mode of action have not been introduced since the 80s and that the AR
problem seems to escalate worldwide, we have to take action.
Monitoring the resistance situation by systematic surveys in different
worm populations is an important means to control AR. I think that the
agricultural industry has to be financially responsible for this work
through their organisations. We have good knowledge on the
development of AR and we know how to deal with it, but we lack
information on the development AR over time in our region.
Prescription from veterinarians must be the only way for the farmers to
obtain anthelmintics. This will subsequently demand a qualified advice
from the veterinarians in order to give the best advice concerning type
of formulations and when to treat the animals to achieve the best effect
of the treatment and at the same time take development of AR into
consideration. This is a challenge in the education of both veterinary
students and veterinary colleagues.
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1. Kaplan RM: Drug resistance in nematodes of veterinary importance. A
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Roepstorff A, Bjørn H, Nansen P: Resistance of Oesophagostomum spp. in
pigs to pyrantel citrate. Vet Parasitol 1987, 24:229-239.
Gerwert S, Failing K, Bauer C: Prevalence of levamisole and benzimidazole
resistance in oesophagostomum populations of pig breeding farms in
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Køhler P: The biochemical basis of anthelmintic action and resistance. Int
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van Wyk JA: Refugia- overlooked as perhaps the most potent factor
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Kettle PR, Vlassoff A, Lukies JM, Ayling JM, McMurtry LW: A survey of
nematode control measures used by sheep farmers and of anthelmintic
resistance on their farms. Part I. North Island and the Nelson region of the
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Nielsen MK, Monrad J, Olsen SN: Prescription-only anthelmintics- a
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Coles GC, Bauer C, Borgsteede FH, Geerts S, Klei TR, Taylor MA, Waller PJ:
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methods for detection of anthelmintic resistance in nematodes of
veterinary importance. Vet Parasitol 1992, 44:35-44.
Sangster NC, Whitlock HV, Russ IG, Gunawan M, Griffin DL, Kelly JD:
Trichostrongylus colubriformis and Ostertagia circumcincta resistant to
levamisol, morantal tartrate and thiabendazole: occurrence of field
strains. Res Vet Sci 1979, 27:106-110.
Martin PJ, Anderson N, Jarrett RG: Resistance to benzimidazole resistance
in field strains of Ostertagia and Nematodirus in sheep. Aust Vet J 1985,
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Le Jambre LF: Egg hatch as an vitro assay of thiabendazole resistance in
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Taylor MA, Hunt KR, Goodyear KL: Anthelmintic resistance detection
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Coles GC, Jackson F, Pomroy WE, Prichard RK, von SamsonHimmelstjerna G, Silvestre A, Taylor MA, Vercruysse J: The detection of
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Lacey E, Redwin JM, Gill JH, Demargherity VM, Waller PJ: A larval
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AGVET, Rahway, NJ.: Boray JC 1990, 177-184.
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(DrenchRite®) for the detection of anthelmintic resistance in
cyathostomin nematodes of horses. Vet Parasitol 2004, 121:125-142.
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in Trichostrongylus colubriformis (nematoda). J Parasitol 1985, 71:645-651.
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Pape M, Posedi J, Failing K, Schnieder T, von Samson-Himmelstjerna G:
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Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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25. Maingi N, Bjørn H, Thamsborg SM, Bøgh HO, Nansen P: A survey of
anthelmintic resistance in nematode parasites of goats in Denmark. Vet
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34. Lindgren K, Ljungvall O, Nilsson O, Ljungström BL, Lindahl C, Höglund J:
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S25
Parasite surveillance and novel use of anthelmintics in cattle
Johan Höglund
Department of Biomedical Sciences and Veterinary Public Health, Div. of
Parasitology and Virology (SWEPAR), Swedish University of Agricultural
Sciences (SLU), SE-751 80 Uppsala, Sweden
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S25
Background: Cattle are economically the most important livestock for
farmers in Sweden. However, both dairy and beef production has been
subjected to considerable structural change over recent decades.
Currently, there are approximately 1.5 million cattle, including ≈370 000
dairy cows producing milk worth 1 m€ [1]. The trend is that the numbers
of dairy cows are decreasing slowly, while beef cows are somewhat
increasing. At the same time as the productivity has been intensified
Page 24 of 31
since the 1950’s in the cattle sector, herd size has increased and the
number of production units, especially the number of dairy farms, have
been dramatically reduced. In contrast, the numbers of organic farms are
steadily increasing. The goal of the Swedish government is to increase
the Swedish organic production of agricultural commodities to 20%
within a three-year period.
According to the Swedish animal welfare regulations, both conventional
and organic cattle must have access to pasture for a period of 2–3
months per year [2]. The grazing season normally occurs between early
May and October. As pasture-borne parasites are ubiquitous wherever
animals are grazing, they remain one of the most important productivity
constraints in Swedish cattle production. These parasites have in common
that they often exhibit simple direct life cycles with infective stages
transmitted on pasture by the faecal–oral route. The most important
pasture-borne parasites of grazing cattle in Sweden are the
gastrointestinal (GI) nematodes Ostertagia ostertagi and Cooperia
oncophora. To a lesser degree, the lungworm Dictyocaulus viviparus, and
also the coccidian Eimeria alabamensis, are important pathogens.
Furthermore, in wet areas the liver fluke Fasciola hepatica, with a complex
life cycle, sometimes cause problems.
The importance of GI-nematodes and lungworms on the productivity in
first-season grazing (FSG) cattle has been demonstrated in a range of
independent grazing trials conducted at SWEPAR over the last decade
[3-8]. According to the results, the weight-gain penalties in unprotected
set stocked FSG animals were on an average in the range of 20 to 65 kg,
compared to simultaneously grazed calves but that were fully protected
from parasites by the use of effective anthelmintics. Combined, these
trials demonstrate the importance of nematode parasites on animal
productivity under Swedish climatic and management conditions. They
also show that good levels of nematode control can be achieved through
the correct use of anthelmintics. However, at the same time there are
concerns that over-dependence on ‘chemical’ control may lead to longterm difficulties. This occurs partly through development of anthelmintic
resistance, but also because these substances are not widely accepted
among consumers. Routine prophylactic use of anthelmintics is not
accepted in organic livestock farming [9]. However, “blanket” treatment of
the whole grazing group or herd is accepted, even on organic farms, in
response to a worm problem after it has been diagnosed.
Although the results from our grazing trials also have shown that good
levels of parasite control can be achieved without anthelmintics, some of
the alternative non-chemical parasite control approaches that we have
tested are impractical. For example, when it comes to the use of natural
pasturelands there are situations where high grazing pressure must be
maintained in order to maintain a profile necessary for the generation of
subsidies. Young and adult stock on Swedish dairy farms are also often
grazed on dedicated pastures, which omits the opportunities for mixed
grazing between different age groups. There are many examples of
organic cattle farmers who have obtained exemptions from the organic
guidelines because their animals have suffered from nematode parasites.
In this contribution, the focus is on diagnostic methods that can be used
for individual and/or herd parasite monitoring in parasite surveillance
programmes. I will also briefly discuss future ways to refine the use of
anthelmintics through targeted selective treatments (TSTs). The latter is a
sustainable deworming method that can be applied in both conventional
and organic cattle production. Finally, some results from an ongoing EU
project (PARASOL, http://www.parasol-project.org/) will be presented.
Sustainable use of anthelmintics: For the foreseeable future it can be
assumed that anthelmintics will constitute the cornerstone of most
parasite control programmes, irrespective of whether they are used alone
or in an integrated programme. However, to preserve the efficacy and to
reach a wider level of acceptance, including organic producers, it is
unavoidable to refine the ways in which anthelmintics are used. One
possibility is to replace current treatment regimes with TSTs. Today in
Sweden, anthelmintics are either administered at strategic times to all
first grazing season cattle at risk (e.g. against GI-nematodes), or given as
metaphylactic mass treatments following the appearance of clinical signs
in some animals in a grazing group (e.g. against lungworm). In order to
create low input and sustainable programs for nematode control, TST
strategies must not only be further developed but also validated under
practical farming conditions. The long-term aim with TST is to minimise
the number of whole herd/flock anthelmintic treatments by directing
treatments towards only those animals/herds that are likely to suffer from
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disease and production loss. Overall, this will reduce the opportunities for
any associated environmental and health risks, while maintaining
agricultural productivity.
The concept of TST is simple and easy to accept, especially in situations
where animals with a high worm burden are easily identified, for
example by showing clinical signs such as coughing, diarrhoea,
emaciation or reduced productivity. However, it is well recognised that
the greatest losses associated with pasture-borne nematode parasites in
grazing livestock are sub-clinical. Economic assessments have also shown
that the financial costs associated with sub-clinical parasitism are
enormous [10]. It can also be argued that it is suboptimal and often too
late to treat with an anthelmintic when clinical signs have already been
observed, as animals showing signs of disease are most likely to
propagate infection. Essential for the TST approach is that there be
access to good and reliable indicators, and identification of treatment
thresholds.
Potential TST indicators: There are many potential TST indicators, which
can be grouped according to whether they are parasitological,
pathophysiological or performance factors. Those indicators based on
traditional parasitological techniques, such as faecal egg counts (FEC),
and in particular pasture larval counts and tracer tests, are generally
impractical, as they are either extremely laborious and/or non-informative
when required [11]. Accordingly, it can be expected that they will not be
feasible as indicators for the purpose of monitoring cattle health. One
exception might be the recently developed FECPAC technology (http://
www.fecpak.com/), which might serve its purpose. However, this
technology must first be carefully tested and evaluated in field before it
can be recommended as a routine measure.
Among the serological tests there are several promising candidates.
Recently it has been demonstrated that both serum pepsinogen
concentrations (SPC) and antibody levels at housing provide very
useful information about previous exposure to nematode parasites.
SPC is a pathophysiological indicator measuring the damage caused to
the abomasal mucosa, and it has been shown to correlate with the
occurrence of parasitic gastroenteritis, both in naturally infected
animals [12] and in young cattle experimentally infected with different
levels of O. ostertagi [13]. However, the use of SPC is restricted, as it
can only be used to predict exposure of FSG animals to this particular
parasite.
Another option is to detect specific IgG antibody serum levels with
immunological methods using ELISA. Currently there are several inhouse ELISAs for the detection of Ostertagia and Cooperia spp. Of
particular interest is the ELISA using crude proteins from whole worm
extracts of O. ostertagi, as it has been demonstrated that this ELISA not
only reflects parasite exposure [13] but also reflects the damage caused
in terms of reduced production traits and milk yield [14,15].
Interestingly, this test was recently evaluated to measure antibody levels
against this abomasal parasite in bulk tank milk [16]. To what level
parasite exposure in cows is correlated with the situation found in
heifers and calves on the same farm remains obscure. Although this
aspect is currently being investigated within PARASOL, it is certainly a
topic that requires more attention in the future. Milk is commonly
tested for a range of infectious diseases, and results from the Ostertagia
test could then easily be incorporated into existing herd health
surveillance programmes.
If not tested beforehand, the suitability of using milk ELISAs against other
important parasites should also be explored. It is important to realise that
the costs of sampling and testing must be minimised before a herd
health monitoring programme can reach more general acceptance
among representatives in authorities, livestock organisations and, not
least, the farming community.
Ongoing research: Since 2006 SWEPAR has been actively involved in
the PARASOL project. This is an ongoing STREP activity coordinated by
Professor Joseph Vercruysse, Ghent University, Belgium, and aimed at
helminth control in grazing ruminants. The work in Sweden has mainly
been focussed on cattle, with the the specific aims: (1) to compare the
pepsinogen and antibody levels against O. ostertagi in FSG animals at
housing, and (2) to predict the situation in the FSG stock
by investigating the antibody levels in bulk tank milk from the same
herds.
A total of 44 dairy farms in south-central Sweden were randomly
selected in 2005. From each farm bulk tank milk was sampled along
Page 25 of 31
with serum from ~10 FSG at the time of housing. The same farms
were also approached to participate the following year, and in 2006
36 farms participated together with one additional farm. In both years
the farmers were asked to complete a form containing questions
about the management of the cattle on the farm, including questions
concerning deworming practices. In the second year the form was
more detailed, and it then also contained questions about utilization
of the pastures and figures on the milk production. Pepsinogen
concentrations and O. ostertagi antibody levels were measured in sera
following ring-testing and according to standard operating procedures
(SOP). In each run a set of standard samples was included to validate
the test results. Also, the milk samples were analysed in a similar
fashion using the O. ostertagi-ELISA from SVANOVA biotechnology,
Uppsala, Sweden.
It was found that the majority of the herds were stabled in September
to October. However, the housing dates varied a lot. Notably, some
farmers housed their animals in late December. In both years, most
farmers treated their FSG with an anthelmintic. However, a large
proportion (38%) was left untreated. The preferred anthelmintic in
2006 was the oxfenbendazole intermittent release device (Systamex
Repidose®). This drug was used on 85% of the farms. No samples had
a serum pepsinogen concentration that exceeded the proposed cut-off
concentration of 3.5 U tyrosin, indicative of subclinical ostertagiosis.
The highest value measured was 2.9 U tyrosin. Still, both the mean
pepsinogen concentrations and serum antibody levels against
O. ostertagi were on an average higher for calves from the untreated
herds. However, there was only a weak positive correlation between
the Ostertagia- antibody levels and pepsinogen concentrations when
the results of the same serum samples was compared (R=0.34).
Furthermore, there was no association between the Ostertagiaantibody levels in bulk tank milk and in sera from the FSG from the
same herd. On the other hand, there was a good agreement between
OD values obtained in different years, and in particular for the milk
samples.
A retrospective study was also carried out to assess the possibility of
using daily weight gain in first-season grazing cattle (FSG) as a marker for
treatment decisions to prevent parasite-induced losses caused by
gastrointestinal (GI) nematodes. Data were combined from three
independent grazing trials, each of which was repeated over 2–3 years, in
order to investigate the influences of parasites on the performance of
FSG cattle subjected to different levels of parasite control. ROC analyses
showed that anthelmintic treatment of animals with a daily weight gain
(Dwgt) of <0.75 kg/day by mid-season had a sensitivity of ~70% and a
specificity of ~50%. It thus seems feasible to base a targeted selective
treatment for FSG cattle on Dwgt recorded approximately 4–8 weeks
after turn-out, provided that it is accepted that some animals will be
dewormed without need. However, these data were pooled from a
number of disparate trials, so that these sources of variation were
included in the experiment but their individual effects cannot be
determined. The next stage is to validate the conclusions in a controlled
field trial.
Acknowledegements: The financial support of PARASOL (Parasite
Solutions), EU thematic priority areas Food Quality and Safety (FP6,
FOOD-2004-T5.4.6.6), and FORMAS (220-2007-1616) and the linguistic
revision by David Morrison is gratefully acknowledged.
References
1. Anon: Jordbruksstatistisk årsbok. 2008, (tab 10.2).
2. DFS: Djurskyddsmyndighetens författningssamling. Saknr L 2007,
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3. Dimander SO, Höglund J, Uggla A, Spörndly E, Waller PJ: The impact of
internal parasites on the productivity of young cattle organically reared
on semi-natural pastures in Sweden. Veterinary Parasitology 2000,
90:271-284.
4. Dimander SO, Höglund J, Spörndly E, Waller PJ: Evaluation of gastrointestinal nematode parasite control strategies for first-season grazing
cattle in Sweden. Veterinary Parasitology 2003, 111:193-209.
5. Höglund J, Svensson C, Hessle A: A field survey on the status of internal
parasites in calves on organic dairy farms in southwestern Sweden.
Veterinary Parasitology 2001, 99:1-17.
6. Höglund J, Viring S, Törnqvist M: Seroprevalence of Dictyocaulus viviparus
in first grazing season calves in Sweden. Veterinary Parasitology 2004,
125:343-352.
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7.
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Höglund J, Törnqvist M, Rydzik A, Ljungström B-L: Best use of doramectin
in first season grazing cattle in Sweden. Svensk Veterinärtidning 2008,
4:11-18, (In Swedish with an English summary).
Larsson A, Dimander SO, Rydzik A, Uggla A, Waller PJ, Höglund J: A 3-year
field evaluation of pasture rotation and supplementary feeding to
control parasite infection in first-season grazing cattle-Effects on animal
performance. Veterinary Parasitology 2006, 142:197-206.
KRAV: Standards for organic certified production. Heatlh and medical care
2007, 5.4:50-52.
Corwin RM: Economics of gastrointestinal parasitism of cattle. Vet
Parasitol 2007, 72:451-457.
Eysker M, Ploeger HW: Value of present diagnostic methods for
gastrointestinal nematode infections in ruminants. Parasitology 2000, 120:
S109-119.
Dorny P, Shaw DJ, Vercruysse J: The determination at housing of
exposure to gastrointestinal nematode infections in first-grazing season
calves. Veterinary Parasitology 1999, 80:325-340.
Ploeger HW, Kloosterman A, Borgsteede FH: Effect of anthelmintic
treatment of second-year cattle on growth performance during winter
housing and first lactation yield. Veterinary Parasitology 1990,
36:311-323.
Ploeger HW, Kloosterman A, Bargeman G, von Wuijckhuise L, van den
Brink R: Milk yield increase after anthelmintic treatment of dairy cattle
related to some parameters estimating helminth infection. Veterinary
Parasitology 1990, 35:103-116.
Ploeger HW, Kloosterman A, Rietveld FW, Berghen P, Hildersson H,
Hollanders W: Quantitative estimation of the level of exposure to
gastrointestinal nematode infections in first-year calves. Veterinary
Parasitology 1994, 55:287-315.
Sanchez J, Dohoo IR, Markham F, Leslie K, Conboy G: Evaluation of the
repeatability of a crude adult indirect Ostertagia ostertagi ELISA and
methods of expressing test results. Veterinary Parasitology 2002,
109:75-90.
S26
Changes in production systems and effects on parasitic infections
Allan Roepstorff*, Stig Milan Thamsborg, Helena Mejer
Danish Centre for Experimental Parasitology, Department of Disease Biology,
Faculty of Life Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870
Frederiksberg C, Denmark
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S26
Summary: A plentity of parasites of great diversity is the rule for all
animals in nature. A successful parasite has to be transmitted from one
host to the next and this transmission is often the weakest point in the
life cycle, as the parasites depend on the surrounding environment for
days to months to become infective either as free-living stages or
within intermediate hosts. For domestic animals, housing and other
factors characterizing the production system thus have a great impact
on transmission, the ectoparasites being an exception due to their
transmission by physical contact between host animals. In the present
paper, the effects of production systems on parasitic infections are
discussed with focus on pigs. During the last century pigs have moved
from traditional husbandry systems with poor hygiene and access to
outdoor areas towards highly intensive, exclusively indoor industries, a
process which has gradually reduced the number of endoparasite
species. Furthermore, ectoparasitic arthropods are easily eradicated by
drug treatment in modern pig enterprises. It is thus only a small
number of protozoan parasites that are common across farms. At
present, the trend of decreasing parasitism is for the first time reversed.
Organic pigs or other free-range pigs make up the best and most
extreme example, and these pigs may harbour many more parasites
than conventional pigs. Only a small minority of domestic pigs,
however, live in organic/free-range herds. It may therefore be more
important in the future that conventional pig herds are also changing
their housing system due to animal welfare issues; straw bedding is
being reintroduced, the pregnant sows are untethered to become freemoving, and facilities may include water sprinkling devices which will
increase the humidity and thereby the survival of transmission stages.
The future challenge of domestic pigs may therefore, for the first time,
be to control an increasing parasite load.
Page 26 of 31
S27
Alternative approaches to control of parasites in livestock: Nordic and
Baltic perspectives
Stig Milan Thamsborg*, Allan Roepstorff, Peter Nejsum, Helena Mejer
Danish Centre for Experimental Parasitology, Department of Veterinary
Disease Biology, Faculty of Life Sciences, University of Copenhagen, Denmark
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S27
Introduction: It is evident from several on-farm surveys that levels of
parasite infections vary markedly between livestock production systems
and from one farm to another [1]. The background for these differences
relates to livestock breeds, different management factors and other
practices that directly or indirectly affect parasite infections, and also to
farmers’ attitudes e.g. the chosen threshold for intervention. This paper
deals with practices or interventions that can be actively applied by
farmers aiming specifically at control of mainly helminth infections, either
by reducing the parasite infrapopulations directly, e.g. by means of
antiparasitic crops, or by limiting the uptake of external stages, e.g. by
pasture management. The term “alternative” approaches has been
applied (despite several options not being very alternative or novel but
relatively old) to denote only limited focus on use of commercial
anthelmintics. Focus will be on approaches relevant to primarily ruminant
and pig production and which can be applied in the Nordic-Baltic context
after some modification or which may serve as a guideline for relevant
research in our region. For practical reasons the options will be dealt with
one at a time although, as pointed out in several reviews [2,3], the
combination of two or more options, or the combination with limited use
of anthelmintics, will in many cases be the optimal approach.
Pasture management: The basic principle of pasture management is
limiting the intake of infective stages of pasture-borne parasite infections.
Pasture management encompasses practices related to grazing: time of
turn-out, length of grazing period, age composition of flocks, co-grazing
with other species and frequency of pasture changes, although other
factors like type of herbage and productivity, stocking rates and parasite
contamination levels at turn-out also are very important. On most
ruminant farms, pasture management is guided by nutritional
requirements of animals in combination with customary practices, and in
general little attention is paid to parasites when the season’s grazing is
planned. Pasture management practices aiming at parasite control have
been extensively researched (and reviewed by [2,4,5] and in most cases
demonstrated to be quite successful in controlling mainly gastrointestinal
nematodes of ruminants. The strategies can be grouped as preventive i.e.
starting off with low (or nil) infection levels in animals and on pastures,
evasive i.e. moving animals away from pastures before harmful
contamination levels are generated, or dilutive strategies i.e. lowering the
ratio between susceptible and resistant animals (or lowering the overall
stocking rate). Despite obvious benefits, these strategies are not readily
adopted by cattle farmers, although still more by organic than
conventional farmers [6,7], and this may be related to the relative ease
and low cost of using anthelmintics compared to labour-intensive fencing
and moving. Furthermore, in sheep grazing management is difficult to
practice totally without drugs.
In dairy cattle, the most susceptible group of animals, i.e. first season
grazing calves, is uninfected at turn-out and if placed on an uninfected
(or lightly contaminated) pasture this will result in good control for the
first half of the season. By repeated moves to clean pastures (e.g. 2-3
times), excellent control is obtained for the entire season [8]. Even
though the first paddock is contaminated, infections are reduced if the
flock is moved by 15 July to a paddock ungrazed the same year [9]. A
recent Swedish study showed very convincingly that a practice of turning
out first year grazing steers (castrated bulls) on paddocks grazed by
second year grazers in the previous season combined with a mid-summer
move to clean pasture, result in acceptable control of gastrointestinal
nematodes [10]. Male animals are generally more susceptible to parasites
than females and steers are believed to have intermediate susceptibility
[11]. Recent Danish studies on nematode infections showed susceptibility
in steers to be very similar to that of heifers [9]. Several studies have
indicated an exacerbating effect of high stocking rates on gastrointestinal
nematode infection levels in both cattle and sheep [12,13] whereas the
effect is less clear in outdoor pigs [14], which presumably is because pigs
tend to stay in the feeding area instead of utilising the paddocks evenly.
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Coccidia in ruminants are often transmitted by overwintering pasture
infections from one year’s young stock to the next [15], and clean
pastures at turn-out (read ungrazed the previous year) are thus crucial in
control [16]. This is a fact often overlooked by sheep or cattle farmers,
e.g. if they have a permanent, after-lambing collecting paddock or if
calves as a rule are grazed in close vicinity of the farm [17]. In the case of
sheep, similar management practices may also result in problems of
nematodirosis in early season (“lamb-to-lamb” disease) as observed in
Denmark [18]. Increasing problems with liver flukes (Fasciola hepatica) are
becoming evident in many places in Northern Europe where grazing of
cattle is re-introduced on natural wetlands for aesthetical reasons and to
maintain biodiversity [19]. In many cases control is achieved by strategic
application of flukicides but it would be relevant to employ evasive
grazing i.e. a move in mid-August as a means of control. However, few
studies, if any, have addressed this approach.
The majority of the pig production in Nordic countries is indoor but
pasture management is relevant in conventional outdoor and organic
farming where the breeding stock, or all stock, have to be outside for a
part of the year. The most common helminths (Ascaris suum and Trichuris
suis) are characterized by hard-shelled eggs and thus sustained longevity
on pasture – up to 10 years (reviewed by [1], despite initial high death
rates [20]. Ongoing Danish experiments using parasite-naïve pigs to trace
the levels of contamination on pastures after initial deposition of eggs,
have yielded 2 interesting results: firstly, transmission levels are increasing
the first 2 years, indicating an unexpected slow development to
infectivity; secondly, infection levels were not markedly decreased after 4
years (Mejer and Roepstorff, 2006, unpublished data). This demonstrates
fully that at present we cannot provide evidence-based recommendations
with regard to paddock rotation in pigs – 2-3 years are obviously not
enough! In contrast, it seems that Oeosphagostomum spp. have a poor
survival over winter [14,21,22] and do not constitute a problem in strictly
outdoor sow herds [23] while the coccidian parasite Isospora suis seems
to be controlled by routine moving of the farrowing huts between
farrowings [24].
The principles of pasture management may be applied to indoor stabling
of pigs in large pens with plenty of straw bedding, e.g. deep-litter
systems. In these cases, the continuous use of a pen will inevitably lead
to increasing levels of parasite infections [25] and all-out-all-in systems
need to be applied. With the forthcoming implementation of EUlegislation stipulating loose housing in enriched environments (e.g.
wallowing) for sows for part of the gestation, an increased risk of
helminth transmission may be anticipated.
Bioactive crops and nutrition: It is difficult to draw a clear distinction
between bioactive crops, plant (herbal) medicine and nutrition as such.
Bioactive crops (nutraceuticals) are plants containing secondary
metabolites that are considered beneficial for their positive effect on
animal health (in casu helminth control) rather than their direct
nutritional value [26]. These crops can be used as fresh forages for
grazing or as conserved feed in the daily ration without any adverse
effect. They may be grown in the normal crop rotation and therefore
draw some attention from commercial seed companies. In plant medicine
dosing is usually a very critical issue and extraction steps are often
included.
In small ruminants, extensive studies worldwide on bioactive crops have
focused on forages rich in condensed tannins (4-8% of dry matter) and
their effect on gastrointestinal nematodes [26,27]. The relevant
temperate/subtropical forages include sainfoin (Onobrychis viciifolia), sulla
(Hedysarum coronarium) and larger trefoil (Lotus pedunculatus), all with
limited distribution in Nordic-Baltic countries. Condensed tannins are
secondary metabolites related to plant defence against herbivory and
constitute a poorly defined group of polyphenolic compounds, based on
flavan-3-ol monomers (prodelphinidins or procyanidins) and characterized
by a protein-binding capacity (tanning!) [28]. The variability is large within
condensed tannins and is related to plant species, growth conditions,
stage of development, cuts etc. Due to this variability many findings are
inconsistent or even contradictory. However, there is now ample
evidence from in vitro and in vivo studies that forages with condensed
tannins may affect all stages of parasitic nematodes, leading to reduced
establishment of infective larvae, lowered fecundity of adult nematodes
and in some cases, reduction in worm burdens. Effects have been
observed against both abomasal and intestinal nematodes but this may,
like in many other instances, depend on plant species or stage, e.g. the
Page 27 of 31
ratio between prodelphinidins and procyanidins [29]. It has long been
debated whether the effects are direct by harming residing/incoming
nematodes, or indirect by improving immunity through more rumen-bypass protein [28]. Recent studies have clearly indicated direct effects of
condensed tannins from conserved sainfoin including inhibited
exsheathment of infective larve, diminished pathological changes in
larvae following short term exposure and reduced penetration of
abomasal mucosa ([29,30]; Severine Brunet, pers. communication, 2008). A
leafy cultivar of chicory (Cichorium intybus) suitable for ruminant grazing,
although not rich in condensed tannins, does exhibit similar effects on
nematodes, and this forage may prove to be more appropriate in the
Nordic-Baltic context [31,26].
It has been known for more than a decade that structure and
composition of the feed may influence establishment and fecundity of
intestinal nematodes of monogastric animals [32]. A low fibre content
and high level of easily fermentable carbohydrates may lower parasitism.
Roots of chicory (Cichorium intybus) and seeds of lupin are rich in such
fermentable carbohydrates, particularly fructans (inulin). In pigs, almost
complete reduction of the egg output of Oesophagostomum spp. has
been acheived by adding purified inulin [33] or dried chicory roots to the
diet [22]. High reductions in worm counts have been observed in some
studies [33,34] but not in all [22]. Incomplete elimination of worms may
explain why depression of egg excretion has been partially reversible as
egg counts were shown to increase when the carbohydrates were
withdrawn from the diet ([33]; Helena Mejer, unpublished data, 2008).
The fermentable carbohydrates are only partially degraded in the small
intestine, and the mechanism of action is most likely related to the
production of short chain fatty acids during their fermentation in the
large intestine [35]. It is believed that the short chain fatty acids directly
or indirectly cause adverse conditions for residing nematodes just as
there is a shift in microbial composition [36]. Consequently, T. suis,
another inhabitant of the large intestine, is moderately affected but
results are inconsistent [37-39]. Furthermore, early larval stages of A. suum
penetrate the large intestine before the migratory liver phase and
establishment of incoming infections may be affected [22] but not
established adult infections (Helena Mejer, unpublished data, 2008). As
the major targets of nematode control in pig outdoor production in the
Nordic context are indeed A. suum and T. suis, these findings need
further investigation to be of practical relevance.
Selective breeding for host resistance: In ruminants, faecal egg counts,
nematode worm counts and related morbidity markers, like pepsinogen
for cattle and anaemia scores for sheep with haemonchosis, show
moderate heritabilities (0.3-0.4), and this forms the basis for a breeding
approach to control of gastrointestinal nematodes, as reviewed by e.g.
[40] and [41]. In large wool producing countries (New Zealand and
Australia) selective breeding for host resistance is now implemented on
many commercial enterprises. Quantitative Trait Loci (QTLs) have been
identified and a first DNA test for sheep is now commercially available
(Catapult Genetics NZ) but breeding values are in most instances still
based on faecal egg counts. Reduction rates in faecal egg counts are
estimated to be approx. 2% annually [42] but the reduction in
anthelmintic treatment frequency remains to been demonstrated.
Selective breeding for resistance has been associated with disadvantages,
e.g. low productivity when unexposed, or increased tendency to scouring
associated with larval exposure, due to higher immunological
responsiveness [43]. Combining low faecal egg counts with other traits, e.
g. productivity, in a selection index is therefore presently considered
most suitable [41].
In pigs, Danish studies based on examination of 200 offspring of known
matings revealed heritabilities of faecal egg counts of A. suum of 0.3-0.4
and of T. suis of 0.4-0.7 [44]. For T. suis the heritabilities depended on
time in relation to start of infection: during the early expulsion phase
heritabilities were highest, probably indicating close genetic control of
the onset of immunity. For Ascaris a number of other parameters like
actual worm burden, total egg output and antibody-levels were also
heritable whereas this was not the case for the size and fecundity of the
worms (Peter Nejsum, unpublished data, 2009). It is obvious that
breeding for increased host resistance is also an option within the pig
industry and may be highly relevant in free-range systems.
Conclusions: Other options, apart from those mentioned above, remain,
including biological control with nematode-trapping fungi against freeliving larvae, copperoxide needles against abomasal nematodes,
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vaccination against gastrointestinal nematodes of sheep, etc. For different
reasons these options are not expected to be available in the Nordic or
Baltic context in the foreseeable future. In contrast, many forms of
grazing management do work in ruminants and should always form the
backbone of any control program. Nutritional supplementation to grazing
ruminants is also immediately available but the costs and benefits need
to be considered – if herbage amount and quality is sufficient very little
extra is gained by additional supplementation. Selective breeding is an
obvious option in small ruminants and perhaps in pigs and beef/dual
purpose cattle. More basic research is needed on bioactive forages with
regard to mode of action and possible active compounds in order to
select the most appropriate forage species/cultivars. None of these
approaches should be considered ’stand alone’ control measures due to
their moderate efficacy and integration with anthelmintics will continue
to be a necessity.
Today it is widely recognized that with the limited arsenal of
anthelmintics and the constant spread of anthelmintic resistance, we
cannot keep livestock free of nematodes during their entire production
life by drug application alone. We need to provide support for the
susceptible young stock, e.g. optimal nutrition and limited parasite
challenge, during the phase of acquisition of immunity until they can
cope with infections. Thus, our mission as veterinarians and
parasitologists has changed accordingly and a new approach to achieve
sufficient levels of immunity with acceptable levels of production loss
and uncompromised animal welfare by prudent (read minimal) use of
anthelmintics has emerged. This represents a shift in paradigm, because
previously the issue of most concern was achieving the highest
production possible. Now we must consider how to transfer this new
message ‘across the fence’ to farmers and extension staff. The future
challenges are indeed numerous.
Acknowledgements: The authors are grateful for valuable comments
from Dr. A. L. Willingham on an earlier version of this paper.
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22. Mejer H: Transmission, infection dynamics and alternative control of
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organic swine herds. Veterinary Parasitology 2002, 106(3):253-264.
24. Roepstorff A, Jørgensen RJ, Nansen P, Henriksen SAa, Skovgaard J,
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Page 29 of 31
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Boes J: The effect of inulin on new and on patent infections of Trichuris
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infection levels in pigs. Heredity 2009, 102:357-364.
S28
Gastrointestinal helminths and lungworms in suckler cow beef herds in
Southern Finland, a pilot study
U Eerola1*, H Härtel2, A Oksanen3, T Soveri4
1
Private Practitioner, Hämeentie 22, 16900 Lammi, Finland; 2LSO Foods Oy,
Animal Health Service, Forssa, Finland; 3Finnish Food Safety Authority Evira,
Fish and Wildlife Health Research Unit, Oulu, Finland; 4Department of
Production Animal Medicine, Faculty of Veterinary Medicine, University of
Helsinki, Finland
E-mail: [email protected]
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S28
Introduction: The number of suckler cow beef herds is increasing in
Finland. Prevalence studies about gastrointestinal parasites and
lungworms of grazing beef cattle in southern Finland are not available.
Systematic anthelmintic treatment is not widely used and there is no
recommended treatment protocol available. The aim of this study was
to obtain basic knowledge of the prevalence of gastrointestinal
parasites and lungworms in grazing suckler cow beef herds in southern
Finland.
Materials and methods: The study was conducted in summer 2002. It
included 13 voluntary beef cattle herds (herd size 26 – 95 adult
animals) in southern Finland. None of the herds had clinical symptoms
of parasitic infection. None of the herds was treated in the spring and
11 of the herds had not used anthelmintic treatments within a year.
The first set of faecal samples were taken from 4-10 calves on 10 farms,
4-10 heifers on 7 farms and 8-12 cows on 13 farms. The first sampling
was done more than 3 weeks after the beginning of the grazing period
and the second sampling was done at the end of the grazing period in
autumn. Faecal samples were investigated at Finnish Food Safety
Authority Evira, Oulu. The methods used were modified McMaster for
gastrointestinal helminth eggs and the Baermann technique for
detecting Dictyocaulus viviparus. Egg count less than 50 eggs/gram
faeces (epg) was considered low infection, 50-500 epg moderate
infection and more than 500 epg heavy infection considering
Trichostrongylidae spp. Dictyocaulus viviparus infections were evaluated
on herd level as negative or positive.
Results: Trichostrongylidae spp were found in all herds in all groups
examined. The egg counts in individual calves varied from 0 to 1540 epg
at the first and from 0 to 780 epg at the second sampling. Egg counts in
heifers varied between 0 - 120 epg and 0 - 140 epg, in older cows
between 0 - 360 epg and 0 - 200 epg, respectively. Only three individual
samples had egg count higher than 500 epg. Median values for calves,
heifers and cows are presented in Table 1.
Table 1 (abstract S28) Median egg count values (epg) of Trichostrongylidae spp. in 13 beef cow herds
calves in summer
calves in autumn
heifers insummer
heifers in autumn
cows in summer
cows in autumn
Farm 1
50
60
M
M
0
0
Farm 2
0
70
M
10
0
0
Farm 3
0
0
M
60
60
0
Farm 4
20
30
20
0
0
0
Farm 5
60
120
20
20
0
0
Farm 6
Farm 7
10
20
50
40
0
0
0
M
0
10
0
0
Farm 81
50
M
0
0
30
M
Farm 9
40
20
M
M
0
0
Farm 10
M
Farm 11
M
2
40
M
50
20
0
0
M
M
0
0
Farm 121
M
M
70
70
0
0
Farm 13
60
160
0
M
0
0
1
2
Dictyocaulus viviparus positive herd
M = Information missing
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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Dictyocaulus viviparus was detected in two herds. Other than
trichostrongylid gastrointestinal parasites (Capillaria sp., Nematodirus sp.,
Moniezia sp., Paramphistomum sp.) were detected in very few samples at
low levels.
Discussion : Gastrointestinal parasites, mainly Trichostrongylidae spp.,
were found widely in beef cattle, but the parasite egg counts were low
or moderate at all farms in all groups of animals. None of the herds
had clinical signs of infection and did not seem to need regular
anthelmintic treatment. However, summer 2002 was exceptionally dry
and warm in southern Finland which may be one reason for low egg
counts. Other gastrointestinal parasites (Capillaria sp., Nematodirus sp.,
Moniezia sp., Paramphistomum sp.) were rare and considered not
important.
The most important finding of this study was some farms having a
subclinical Dictyocaulus viviparus infection. In light of the low incidence of
disease in Finland, subclinical infections are a risk in cattle trade and
should be considered.
S29
The prevalence of internal parasites in wild boar farms in Finland
Outi Hälli*, Eve Ala-Kurikka, Olli Peltoniemi, Mari Heinonen
Department of Production Animal Medicine, University of Helsinki,
Saarentaus, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S29
Background: In Finland, the most important internal parasites in
domestic pigs are nematode Ascaris suum and coccidia Isospora suis. As
the environmental conditions and management practices in wild boar
(Sus scrofa) outdoor farming are suitable for parasites during most
seasons, we wanted to explore the parasite burden of wild boars in
Finland. This kind of research has not been carried out earlier in our
country. Economical losses caused by internal parasites, especially
ascarids, are mainly due to reduced daily weight gain and feed
conversion ratio [1].
Materials and methods: Based on a national record of wild boar farmers,
a sampling frame of farms was compiled. Every farm on that list was
contacted first by mail and the non-responders received a phone call from
research group personnel. All volunteer farms that still had wild boars
were included. From all animals slaughtered in study farms during the
study period (autumn 2007 – spring 2008), a faecal sample was obtained
directly from rectum after slaughter. Faecal egg or oocyst counts regarding
Ascaris suum, coccidia, Strongylus and Trichuris suis were counted by the
concentration McMaster technique. The number of positive farms (at least
one animal with parasite eggs in faecal sample) and summary statistics of
egg counts for every parasite type was calculated.
Results: Altogether 113 samples were collected from 22 farms, a median
of 4 samples (1-15) per herd. The median age of sampled wild boars was
18 months. Mean age was found to be 21,5 months (standard deviation
14,5). The number of positive farms can be seen in Figure 1. and
summary statistics for egg or oocyst counts for different parasites studied
can be found in Table 1.
Conclusion: Almost all farms were positive regarding coccidia. The exact
diagnosis of the species of the oocysts was not reached, whether they
were Isospora or Eimeria. Although the established oocyst counts
probably are harmless for adult animals, the risk for piglets could be
substantial because of environmental contamination, especially in case of
Page 30 of 31
Table 1 (abstract S29) Summary statistics for egg counts
(epg) for coccidia, Strongylus, Ascaris suum and Trichuris suis.
Parasite
Mean, epg
SD, epg
Min, epg
Max, epg
Coccidia
6 118
1987
0
102 000
Strongylus
300
945
0
6 150
Ascaris suum
Trichuris suis
29
0
15
0
0
0
1 450
0
Isospora. Smaller number of animals and farms were Strongylus or Ascaris
suum positive. Adult animals are known to be able to develop immunity
towards ascarids, thus the low egg burden in sampled animals was quite
expected.
Reference
1. Corwin RM, Stewart TB: Internal Parasites. In Diseases of Swine. Edited by:
Straw BE, D’Allaire S, Mengeling WL, Taylor DJ Ames, Iowa: Iowa State
University Press; 1999:713-730.
S30
Cross-infection of gastrointestinal nematodes between winter corralled
semi-domesticated reindeer (Rangifer tarandus tarandus) and sheep
(Ovis aries)
Saana-Maaria Manninen*, Antti Oksanen, Sauli Laaksonen
Finnish Food Safety Authority Evira, Fish and Wildlife Health Research Unit,
Oulu, Finland
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S30
Summary: The increasing number of sheep (Ovis aries) in the reindeer
(Rangifer tarandus tarandus) herding area in North Finland and
supplementary winter feeding of reindeer in corrals shared with sheep
causes potential for cross-infection of gastrointestinal nematodes
between reindeer and sheep. The aim of this study was to elucidate
this potential. The study included 46 animals, of which 12 reindeer
and 8 sheep had shared a corral. Twelve reindeer had no known
contact with sheep. Both reindeer groups shared free ranging areas
with wild moose (Alces alces). Two moose were included in this study,
as were 12 sheep which had no contact with other ruminants. After
slaughter in September-November abomasa and proximal small
intestines were collected and examined for gastrointestinal
nematodes. The parasites were collected, counted and identified.
Following species were found in reindeer: Ostertagia gruehneri,
Ostertagia arctica, Spiculopteragia dagestanica, Nematodirus tarandi,
Nematodirella longissimespiculata and Bunostomum trigonocephalum.
Sheep were infected with Teladorsagia circumcincta, Teladorsagia
trifurcata, Ostertagia gruehneri, Ostertagia arctica, Nematodirus filicollis
and Nematodirus spathiger. Spiculopteragia dagestanica and Ostertagia
gruehneri were identified in moose. Ostertagia gruehneri, which is
considered to be a reindeer parasite, was only found in the sheep that
had shared a corral with reindeer. These sheep were not found to be
infected with other abomasal nematodes. The reindeer that had
shared a corral with sheep were not infected with nematodes usually
having sheep as their primary host.
Figure 1 (abstract S29) Number of farms with at least one pig positive for different parasites in fecal examination (22 farms included in the study).
Acta Veterinaria Scandinavica 2010, Volume 52 Suppl 1
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S31
Intestinal parasite infection exposes grouse to canine predators
Marja Isomursu1*, Osmo Rätti2, Pekka Helle3, Tuula Hollmén4
1
Finnish Food Safety Authority Evira, Research Department, Fish and Wildlife
Health Research Unit, P.O.Box 517, FI-90101 Oulu, Finland; 2Arctic Centre,
University of Lapland, P.O.Box 122, FI-96101 Rovaniemi, Finland; 3Finnish
Game and Fisheries Research Institute, Oulu Game and Fisheries Research,
Tutkijantie 2 E, FI-90570 Oulu, Finland; 4Alaska Sealife Center, 301 Railway
Avenue, P.O. Box 1329, Seward, AK 99664, USA
Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S31
Background: Sublethal parasite infections may cause mortality indirectly
by exposing the host to predation. The best known example of this
among birds is red grouse in which caecal nematode infection causes
increased risk of predation and can even affect population dynamics [1].
Intestinal helminth parasites are common in forest grouse, capercaillie
Tetrao urogallus, black grouse Tetrao tetrix and hazel grouse Bonasa
bonasia [2], and these grouse are valuable prey for several species of
predators. We evaluated the hypothesis that parasite infection makes the
host more vulnerable to predation by comparing the intestinal parasite
infection status of grouse hunted with a trained dog to that of grouse
hunted without a dog. Hunting with a dog can be regarded as close
simulation of natural predation because the dog presumably locates the
prey by the same cues as wild canine predators.
Material and methods: We collected whole grouse intestines from
hunters and received 623 samples of which the bird species, age class
and sex were determined. All sample birds were shot with a shotgun
during legal hunting season in September and October. Intestines were
cut open and parasites visible to naked eye or stereomicroscope were
extracted and identified. The associations between host sex, age, species,
the month of sampling, the use of dog and the occurrence of intestinal
Figure 1(abstract S31) Prevalence of cestodes in grouse hunted with a
dog or without a dog. Shaded bars = with dog, open bars = without
dog.
Page 31 of 31
helminths were studied using hierarchical loglinear modelling with
backward elimination procedure (P = 0.05) (SPSS programme ver. 11.5).
Two different models were studied, one for cestodes (all three species
pooled together) and one for nematodes.
Results and conclusions: Grouse were infected by four helminth species:
a nematode Ascaridia compar and cestodes Skrjabinia cesticillus, Paroniella
urogalli and Hymenolepis sp. Nematode infection was not connected to
dog-assisted hunting. However, there was a significant interaction
between cestode infection and the use of dog (P < 0.01). Cestodes were
more common in grouse hunted with a dog (see Figure 1). Cestodes
were mostly parasites of juvenile grouse but even among juveniles only,
cestodes were more prevalent in the dog-assisted hunting bag. The
results suggest that mammalian predators prey more selectively on
parasitized individuals and that intestinal parasites may contribute to the
high mortality of juvenile grouse through increased predation.
This abstract is based on a recent paper published in Annales Zoologici
Fennici by the same authors [3].
References
1. Dobson A, Hudson P: The interaction between the parasites and
predators of red grouse Lagopus lagopus scoticus. Ibis 1995, 137:S87-S96.
2. Isomursu M, Helle P, Rätti O: Intestinal helminths in Finnish grouse.
Suomen Riista 2004, 50:90-100, (In Finnish with English summary).
3. Isomursu M, Rätti O, Helle P, Hollmén T: Parasitized grouse are more
vulnerable to predation as revealed by a dog-assisted hunting study.
Ann Zool Fennici 2008 in press.
Cite abstracts in this supplement using the relevant abstract number,
e.g.: Isomursu et al.: Intestinal parasite infection exposes grouse to
canine predators. Acta Veterinaria Scandinavica 2010, 52(Suppl 1):S31