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GB surveillance
Safeguarding
public and animal
health
Avian diseases
Date: January – March 2010
Quarterly Report: Volume 14. No. 1
Page
Contents
The Veterinary Investigation
Diagnosis Analysis database
- VIDA - diagnoses are
recorded
on
the
VLA
FarmFile
database
and
comply
with
agreed
diagnostic criteria against
which regular validations and
audits are undertaken.
The investigational expertise
and
comprehensive
diagnostic
laboratory
facilities of both VLA and
SAC
are
widely
acknowledged, and unusual
disease problems tend to be
referred to either. However,
recognised conditions where
there is either no diagnostic
test, or a clinical diagnosis
offers sufficient specificity to
negate
the
need
for
laboratory investigation, are
unlikely to be represented.
The report may therefore be
biased in favour of unusual
incidents or those diseases
that
require
laboratory
investigation for confirmation.
VLA Regional Laboratories
and
SAC
Veterinary
Surveillance Centres have
UKAS Accreditation and
comply with ISO 17025
standard.
Overview
Factors influencing disease and submission rates
Avian notifiable disease - Investigations in Great Britain
Avian notifiable disease - International events summary
Farm visit investigations
Chemical food safety incidents
Zoonoses
Cross-sector avian diseases
Endemic disease surveillance
References
2
2
7
9
11
11
12
12
13
15
Highlights
•
Substantial increase in diagnostic submissions received by the VLA
compared with the same time last year. This may be a reflection of
improving financial and economic conditions (page 7).
•
Avirulent avian paramyxovirus type 1 (APMV-1) and H2N3 LPAI isolated
from a flock of free-range broilers. A routine scanning surveillance
submission yielded an APMV-1 isolate. Follow up statutory disease
investigations unusually resulted in the additional identification of an H2N3
LPAI virus. Wild birds were suspected to be the source (page 8).
•
Emergent H5N1 HPNAI genotype circulating in poultry and wild birds in
Eurasia. Romania and Bulgaria are the only EU Member States to report
detections so far this year. Vigilance for suspect disease required (page 9).
•
First detection of IBV European QX-like strains in commercial poultry.
Previously only found in backyard poultry flocks in GB (page 12).
•
Chick anaemia, Transmissible viral proventriculitis and Marek’s disease
amongst other infectious diseases affecting commercial poultry. Such
diseases vary in frequency, but are economically important. Where
available, prevention by vaccination is widely practised (page 14).
•
Further diagnosis of ORT as part of respiratory disease complex in
pheasants. ORT and APMV-2 co-infection reported last quarter (page 16).
editor:
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
OVERVIEW
FACTORS INFLUENCING DISEASE AND SUBMISSION RATES
Many factors combine to influence the patterns of disease in poultry, and the ability to detect changes to
these patterns through scanning and active surveillance. They include:
1. POULTRY DEMOGRAPHICS (data extracted from the Great Britain Poultry Register - GBPR)
On the 1st January 2010 in Great Britain (GB) there were 20,088 registered poultry premises (with 50 or
more birds), holding a total of 238,253,436 birds. In addition, a total of 15,143 flocks with less than 50
birds were registered, comprising a total of 241,237 birds (Table 1).
In comparison, On the 1st January 2009 there were 17,072 registered poultry premises (with 50 or more
birds) holding a total of 238,764,225 birds. In addition, a total of 14,196 flocks with less than 50 birds
were registered, comprising a total of 243,507 birds.
NB: It is only mandatory for premises with 50 or more birds to register on the GBPR. Some premises
with fewer birds have registered voluntarily, but many will not be represented.
Table 1. GB poultry demographics as of 1st January 2010
GBPR 01 January
2010
(Premises with 50 or
more birds)
England
Scotland
Wales
Total
Premises
Birds
Premises
Birds
Premises
Birds
Premises
Birds
Layers and layer
breeders (chickens)
4,664
29,134,446
379
6,226,103
343
1,344,852
5,386
36,705,401
Broilers and broilers
breeders (chickens)
1,754
114,535,906
196
12,859,359
133
7,450,635
2,083
134,845,900
Turkeys
1,152
9,178,475
41
25,617
77
412,200
1,270
9,616,292
Ducks and geese
2,214
5,757,403
285
208,028
150
75,497
2,649
6,040,928
Game birds*
7,271
42,586,279
1,080
5,726,370
349
2,732,266
8,700
51,044,915
Total premises with
50 or more birds
17,055
201,192,509
1,981
25,045,477
1,052
12,015,450
20,088
238,253,436
Flocks registered with
GBPR with less than 50
birds
13,019
220,764
1,099
1,881
1,025
18,592
15,143
241,237
*Game birds = pheasants and partridges.
•
•
•
•
The sum of the premises column will not equal the total, as some premises will have multiple
species.
Turkeys and game birds numbers alter by month. For these premises the GBPR requires that the
number of birds entered on the form is the number of birds ‘usually present on the premises’.
Small flocks with fewer than 50 birds do not have to register with the GBPR, so “backyard” flocks
are under-represented.
Species not included in this report, but registered on the GBPR are guinea fowl, quail, pigeons
reared for meat, ostriches, emus, rheas, cassowaries and kiwis.
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
Figure 1. Traditional poultry density distribution on 1st January 2010
3
GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
Figure 2. Game bird density distribution on 1st January 2010
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
2. ECONOMICS OF THE POULTRY INDUSTRY
1) Placings (Figures 3-6 refer to the number of birds placed from UK hatcheries per quarter, in millions).
Figure 4. Av UK Quarterly figs for Commercial
Layer Chick Placings from UK hatcheries
(Average Monthly figures)
Figure 3. UK Quarterly figs for fem ale Broiler
Parent Chick Placings from UK hatcheries
(Average Monthly figures)
2.9
0.70
2.8
0.60
2.7
millions
millions
0.50
0.40
0.30
0.20
2.6
2.5
2.4
2.3
0.10
2.2
0.00
08-2
08-3
08-4
09-1
09-2
09-3
09-4
10-1
2.1
08-2
Figure 5. UK Quarterly figs for Commercial
Broiler Chick Placings from UK hatcheries
(Average Monthly figures)
2.5
72
2.0
millions
millions
70
68
66
62
0.0
08-2
60
09-1
09-2
09-3
09-4
09-2
09-3
09-4
10-1
1.0
0.5
08-4
09-1
1.5
64
08-3
08-4
Figure 6. UK Quarterly figs for Turkey Poults
Placings from UK hatcheries
(Average Monthly figures)
74
08-2
08-3
08-3
08-4
09-1
09-2
09-3
09-4
10-1
10-1
2) Slaughterings (Figures 7-8 refer to the number of meat birds slaughtered per quarter, in millions).
Figure 7. UK Quarterly Figs for Turkey
Slaughterings (Average monthly figures)
Figure 8. UK Quarterly figs for Broiler
Slaughterings (Average monthly figures)
70
2
66
1
millions
millions
68
1.5
0.5
0
08-2
08-3
08-4
09-1
09-2
09-3
09-4
10-1
64
62
60
58
56
54
08-2
5
08-3
08-4
09-1
09-2
09-3
09-4
10-1
GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
3) Meat production (Figures 9-10 refer to overall poultry meat production and trade per quarter, in 1000 tonnes).
Figure 10. Total Poultry Meat Trade
(Average Monthly figures)*
Figure 9. Total UK Poultry Meat Production
(Average Monthly Figures)
45
140
40
35
1000 Tonnes
1000 Tonnes
130
120
110
30
25
20
15
10
5
100
08-1
08-2
08-3
08-4
09-1
09-2
09-3
09-4
10-1
0
08-2
08-3
08-4
09-1
Import
09-2
09-3
09-4
Export
Comment
There was a 6.1% increase in broiler chick placings in March 2010 compared with March 2009, and over
the quarter, an industry record of 219 million broiler chicks placed (7.0% rise compared to the same
quarter during 2009). Broiler slaughterings in March were also 7.5% higher (a total of 64.2 million birds).
Day-old layer pullet placings in March 2010 were 27% higher than in March 2009, with a total of 8.5
million layer chicks placed this quarter. However, turkey poult placings were 11% lower than March
2009, continuing a long-term downward trend. This quarter saw a total of 2.9 million turkey poults placed,
the first time this figure has dropped below 3 million and a 7.6% fall compared with the same period
during 2009 (http://www.defra.gov.uk/evidence/statistics/foodfarm/food/poultry/index.htm).
Egg statistics (http://www.defra.gov.uk/evidence/statistics/foodfarm/food/eggs/index.htm) that were
released in February 2010 showed the following:
•
•
•
24,616 thousand cases of eggs were packed in the UK in 2009, a 0.3% fall on 2008.
Free-range and organic eggs accounted for 41% of eggs packed in the UK in 2009, compared
with 38% in 2008.
The average packer to producer price for all eggs was 72.6 pence per dozen in 2009, a 2.8% rise
on 2008.
The data shown in the histograms above for the most recent quarters may be subject to revision.
3. WEATHER AND CLIMATE (Information courtesy of the Met Office)
January 2010 was a particularly cold and dry month in GB with much snow nationally and temperatures
well below the mean, by -2.5oC on average, for the 30-year averaging period, 1971-2000. Rainfall in
England, Wales and Scotland for the quarter was between 50% and 75% of the mean, and February
was also drier than usual in most of GB except southern England, which experienced about 130% of
mean monthly rainfall. It was also colder than usual in February, by approximately -1.5oC on average.
Rainfall was slightly below mean and temperatures were close to usual in March throughout GB.
The continued very low temperatures in January 2010 affected poultry producers resulting in additional
heating costs, increased food consumption and lower production, with ‘wet litter’, unevenness and poor
target weights reported and investigated in some broiler flocks.
Met Office anomaly graphs showing the monthly variation and trends for a selected year can be
accessed at: http://www.metoffice.gov.uk/climate/uk/anomalygraphs/index.html. The graphs cover the
30-year averaging periods, 1961-1990 and 1971-2000.
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
SCANNING SURVEILLANCE - POULTRY SUBMISSION TRENDS
During the quarter the total number of diagnostic submissions and poultry carcases submitted in both GB
and to the VLA were the highest since 2006 (Table 2), albeit with the number of submitted poultry
carcases being of similar magnitude to the first quarter of 2007 and 2008 respectively. Furthermore,
compared with the same period last year, a substantial increase in the number of both diagnostic
submissions (by approximately one-third) and poultry carcases submitted (by approximately one half) to
the VLA was recorded. The exact causes of this variation are not known. However, it is suggested that
changes in financial and economic conditions over the intervening period may be partly responsible.
Table 2: Poultry Diagnostic Submissions in GB – 1st Quarter
Submissions
January –
March
Carcases
VLA
SAC
Total
VLA
SAC
Total
2010
452
40
492
1,183
106
1,289
2009
313
43
356
650
108
758
2008
342
52
394
1,127
150
1,277
2007
428
34
462
1,073
57
1,130
2006
593
61
654
1,334
53
1,387
AVIAN NOTIFIABLE DISEASE – GREAT BRITAIN
Domestic poultry
No outbreaks of avian notifiable disease (AND) in domestic poultry (excludes pigeons) were confirmed
during the quarter (January to March 2010) in Great Britain (Table 3). However, clinical material was
submitted to the National Reference Laboratory (NRL) for Avian Influenza (AI) and Newcastle Disease
(ND), VLA Weybridge, from two cases of suspected AND. The premises were located in Cornwall and
Cumbria, and a total of 123 samples were tested comprising sera (40), oropharyngeal swabs (40),
cloacal swabs (40) and carcases (3). Practitioners are reminded to report and ask clients to report any
cases of suspected AND urgently to the local Animal Health Office.
Table 3: Summary of AND Report Cases submitted for laboratory investigation in GB – 1st Quarter
No. of
Cases*
No.
Positive**
Q1-2009
4
Q1-2010
2
Period
Number and type of samples submitted
†
‡
Total
Samples
OPS
CS
Sera
Carcase
0
60
60
60
20
200
0
40
40
40
3
123
No. of Cases*: Total number of suspected AND cases investigated in Great Britain during Q1.
No. of Positives**: Number of notifiable AI positive cases (H5 & H7) following statutory virological and
serological testing. However, H6N1 LPAI was detected in two turkey breeder flocks during February
2009 and an avirulent APMV-1 virus and H2N3 LPAI virus were detected in free-range broilers
sampled during March 2010 (see below).
OPS†: Oropharyngeal swab.
CS‡:
Cloacal swab.
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
One of the AND Report case investigations arose following the detection of an avian paramyxovirus type
1 (APMV-1) isolate from a routine scanning surveillance submission. Respiratory signs and the daily loss
of 5-6 free-range broilers aged 8-weeks over at least a 5-day period from a flock of 400 had prompted
the initial submission of two carcases to a VLA-RL. The affected group had shown limited or no response
to antimicrobial treatments. Further testing confirmed this to be an avirulent Queensland V4-like (lineage
1) APMV-1 (ICPI 0.0) - hence not Newcastle disease - and of suspected wild bird origin. In addition, an
H2N3 LPAI virus was also isolated (non-statutory subtype as not H5 or H7 and of low pathogenicity). On
this basis, as both viruses were of low virulence, premises restrictions were lifted and no further sanitary
measures taken. A further 350 free-range broilers (unaffected) and 60 ducks were on the premises. The
AMPV-1 lineage 1 isolates can be roughly divided into ‘Ulster 2C-like’ and ‘Queensland V4-like’. These
two groups of viruses have been isolated frequently from wild waterfowl throughout the world since the
late 1960s and have also been extensively used as live vaccines. However, in the UK the currently
licensed lineage 1 vaccines originate from Ulster 2C strains. Clinical signs (respiratory, diarrhoea, egg
drop) may be see in naturally infected chickens.
National Survey for AI viruses of subtypes H5 and H7 in Domestic Poultry
All EU Member States are required to undertake annual surveys for notifiable avian influenza (H5 and
H7) in poultry (http://www.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/ai/keptbirds/index.htm). Such
surveys have been running since 2003, and have been a success thanks to cooperation between
individual poultry keepers, the poultry industry, Animal Health, VLA and Defra. This years survey started
in April to allow for sampling of game bird flocks (game ducks and pheasant and partridge breeders).
Other types of poultry will be included in the survey from early August 2010 onwards.
In GB, a random list of poultry premises is selected and stratified on chicken, turkey, duck, goose and
game bird flocks. Blood samples are taken from a number of birds on each premises, which are then
screened for the presence of antibodies to AI viruses (subtypes H5 and H7) by HI test. If any H5 or H7
HI test results are not negative according to the methods prescribed in the EU Diagnostic Manual for AI
(CEC, 2006), the premises is subject to a follow up investigation and sampling.
Pigeon Paramyxovirus type 1 (PPMV-1) investigations
Four cases of suspected PPMV-1 infection were investigated during the quarter, three of which were
located in England and one in Wales. The presence of PPMV-1 was confirmed on three occasions by
virus isolation (VI) in embryonated fowls’ eggs (Table 4).
Table 4: Summary of PPMV-1 cases submitted for laboratory investigation in GB – 1st Quarter
No. of
Cases
No. of
Subm.
(No. of
Tissues)*
No. of
Subm.
(No. of
Sera)
Q1-2009
5
4 (14)
Q1-2010
4
4 (19)
Period
No. of Tissue Submissions (No. VI positive)‡
GB
England
Scotland
Wales
1 (5)
4 (1)
3 (0)
1 (1)
0 (0)
0 (0)
4 (3)
3 (2)
0 (0)
1 (1)
No. of Subm. Tissues*: Samples include pigeon carcases, tissues and swabs.
PPMV-1, a virulent variant Newcastle Disease (ND) virus, is the causative virus of the continuing
panzootic that began in racing and feral pigeons almost 30 years ago. Although a pigeon variant virus,
PPMV-1 still meets the internationally recognised virulence criteria, and under EU legislation when it is
found in any poultry species the infection must be regarded as ND. In Great Britain, the last outbreak of
ND in domestic poultry caused by PPMV-1 infection was detected in Scotland during October 2006
(Irvine and others, 2009).
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
Great Britain AI Wild Bird Surveillance (AIWBS)
H5N1 Highly Pathogenic Notifiable Avian Influenza (HPNAI) was not detected from any of the 1,741 wild
birds sampled and tested during the last quarter in Great Britain. 1,471 wild birds were sampled as part
of wildfowl trapping activities and 270 wild birds were sampled that had been ‘found dead’. For further
details please refer to the GB Wildlife Disease Surveillance Partnership quarterly reports
(http://www.defra.gov.uk/vla/reports/rep_surv_wildlife.htm). The last detection of H5N1 HPNAI in wild
birds in GB was during January-February 2008, from ten Mute swans (Cygnus olor) and one Canada
goose (Branta canadensis) in South Dorset (Defra, 2008).
AIWBS activities in Great Britain were revised in October 2008, focussing on the patrolling of designated
reserves by skilled wild bird ecologists and wardens. Members of the public are also asked to remain
vigilant for 'mass mortality’ incidents of 10 or more birds and report these to the Defra Helpline (08459 33
55 77). Further information is available at:
http://www.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/ai/wildbirds/index.htm#surveillance
INTERNATIONAL TRADE
A total of 32 submissions were received for the purposes of International Trade, health certification and
monitoring testing during the quarter.
Export: Domestic poultry & Captive birds
In total, 29 submissions were received from a variety of species of poultry and captive birds for testing
for Export purposes, all of which gave negative results for the presence of AI and/or ND. A total of 20
poultry submissions were received and tested, of which twelve were from chickens, two from duck flocks
and six submissions from turkeys. Destination countries included Canada, Japan and Thailand. A further
nine captive bird submissions were received and tested, of which three were from pigeons, five were
from psittacine and passerine bird species with one submission from a raptor. Destination countries
included Barbados, Hong Kong, South Africa and the United Arab Emirates.
Imported Captive birds in Quarantine
Three submissions were received from raptor (2) and psittacine (1) bird species imported from the USA,
with testing giving negative results for the presence of AI and ND.
AVIAN NOTIFIABLE DISEASE: INTERNATIONAL EVENTS SUMMARY
(JANUARY – MARCH 2010)
Reported detections during this quarter of the avian notifiable diseases, Avian Influenza and Newcastle
disease in Europe and worldwide are summarised below.
H5N1 HPNAI
Romania reported the detection of H5N1 Highly Pathogenic Notifiable Avian Influenza (HPNAI) in
backyard poultry outbreak during mid-March. This outbreak involved a cluster of six backyard flocks
within a 400m radius on the Danube delta, in the Tulcea region of Romania (OIE, 2010a). A second
outbreak in Romania, affecting one backyard flock located 55km east of the first cluster, and also on the
Danube delta, was reported during late March (OIE, 2010b). These were the first reported outbreaks in
an EU Member State since October 2008, when the virus was detected in commercial ducks in Saxony,
Germany
(OIE,
2008;
summary
also
in
AQR
Vol.12,
No.3:
http://www.defra.gov.uk/vla/reports/docs/rep_survrep_qtlya0308.pdf).
In a separate incident, Bulgaria reported the detection of H5N1 HPNAI in a Common Buzzard (Buteo
buteo) found dead in Varna region on the Black Sea coast on 29 March 2010 (OIE, 2010c) that was
suspected to have scavenged infected carcasses. The last report of H5N1 HPNAI in wild birds in the EU
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
was over one year ago, during March 2009, from a Mallard duck (Anas platyrhynchos), one of 39 wild
birds that had been shot and sampled during January 2009 at Lake Starnberg, near Munich, Germany
(see AQR Vol.12, No.1: http://www.defra.gov.uk/vla/reports/docs/rep_survrep_qtlya0109.pdf).
These reported detections of H5N1 HPNAI in backyard poultry and wild birds in Romania and Bulgaria
respectively, have provided evidence for both the ongoing westward spread of the virus from central Asia
and, perhaps more importantly, the emergence and circulation of a novel H5N1 HPNAI genotype - clade
2.3.2 - in both of these bird populations. Laboratory testing of the Romanian isolates suggested that the
viruses belong to clade 2.3.2 and share a high similarity (100% nucleotide identity in the HA gene)
indicative of a direct causal relationship or derivation from a common ancestor. The two backyard cases
were almost certainly related to direct spread between poultry following the initial introduction, possibly
mediated through contact with wild birds. Sequence analysis of the isolate from the wild bird in Bulgaria
also indicated H5N1 HPAI clade 2.3.2 with 99.9% similarity to the viruses isolated from the Romanian
outbreaks. During early 2010, poor weather conditions around the Baltic saw the arrival of large numbers
of stressed and starved wild geese (and other wild birds) in these areas (Roberts and others, 2010).
Poultry outbreaks with this genotype were also reported from Nepal during January 2010 (Sabirovic and
others, 2010; OIE, 2010j).
Prior to these events in Romania and Bulgaria the most westerly detection of H5N1 HPNAI clade 2.3.2
was during November 2009, from a rock dove (Colombia livia) found sick on a residential balcony in
Moscow, Russia (OIE, 2009a). This followed multiple wild bird incidents in Central Asia during May to
August 2009 (AQRs April to September 2009: http://www.defra.gov.uk/vla/reports/rep_surv_avian.htm).
Further sequence and phylogenetic analyses of H5N1 HPNAI viruses detected from the wild bird
incidents that occurred during June 2009 in Eastern Russia (OIE, 2009b), specifically at Ubsu-Nur lake
in Respublika Tyva (a border region with north-western Mongolia), revealed them to be closely related to
viruses isolated from wild bird mortalities in Mongolia around that time (Sharskov and others, 2010).
Similar seasonal and geographical patterns of H5N1 HPNAI detections in wild birds and poultry to those
seen during 2009 were first reported in 2005 (Defra, 2005), emanating from Central Asia to the north and
west, as well as into Africa, and ultimately towards and across Europe (Defra, 2009) involving clade 2.2
viruses during 2006-2008. The frequency of clade 2.2 detections in the EU has since reduced. Currently
it is not known whether the clade 2.3.2 genotype is replacing clade 2.2, or if they will become sympatric.
Similarly, it remains to be seen if the apparent westward spread of this novel genotype continues within
the EU. It should be noted that, according to expert ornithological advice, no regular migratory
movements of wild birds occur from Romania and Bulgaria to the UK (Roberts and others, 2010). Such
seasonal detections in the Baltic/Danube delta region have, in previous years, seen other reported H5N1
HPNAI detections around the Black Sea, notably the Crimean peninsula (Ukraine) and the Turkish coast
(Irvine and others, 2008), most likely as migratory birds follow the Black Sea/Mediterranean flyway.
During January 2010, Israel reported an outbreak of H5N1 HPNAI in a high biosecurity flock of 43,000
broiler breeder pullets aged 16-weeks in Haifa, Hamerkaz region (OIE, 2010e), the first outbreak since
January 2008. Birds in only one of the three houses were clinically affected, with daily mortality >1%. All
birds on the premises were culled with surveillance and other disease control measures implemented.
No further outbreaks have since been reported. A suggested source of infection was the transit of wild
bird droppings into the affected poultry house - no footbaths were used at house entrances. The location
of this outbreak is 8 kilometers away from the previous H5N1 HPNAI outbreak in Binyamina in January
2008. Sequence data from this outbreak indicated the virus groups in clade 2.2.1 with viruses from North
Africa. It shares >99% homology with virus isolated from Egypt in 2009, and slightly less (96.1%) with
virus isolated from the previous outbreak in Israel in 2008 (OIE, 2010e; Chaimovitz, M., 2010; Sabirovic
and others, 2010).
Elsewhere, H5N1 HPNAI outbreaks in domestic and backyard poultry continued to be reported in several
Asian countries where infection has long been recognised and/or is endemic including Bangladesh,
Bhutan (for the first time, and on the border with West Bengal), Cambodia, India (West Bengal),
Myanmar, Nepal and Vietnam (Sabirovic and others, 2010). In addition, during January 2010, routine
AIWBS activities in Hong Kong resulted in the detection of H5N1 HPNAI from a wild Oriental magpie
robin (Copsychus saularis - a common resident species), found dead in a park in Hok Tau (OIE, 2010d).
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
H5 & H7 LPNAI
Italy reported four low pathogenicity notifiable avian influenza (LPNAI) outbreaks (H5 and H7 subtypes)
following the detection of antibodies in the absence of clinical signs (Sabirovic and others, 2010). Dealer
and/or multi-species poultry premises appeared to be a relevant risk factor. During March, Denmark
reported an H7 LPAI outbreak in a flock of breeding mallard ducks following routine serological
surveillance. Sampling of epidemiologically linked premises identified one further positive farm of
breeding mallards in a different region. Sanitary measures including culling were implemented in all of
these cases.
Elsewhere, H5N2 LPAI was reported affecting a chicken flock (~4% mortality, reported co-infection with
chicken infectious anaemia virus, mycoplasmosis and Infectious Bronchitis virus) in Chang Hua region,
Taiwan during January 2010. At least two further premises were identified during February and March as
a result of outbreak surveillance activities (OIE, 2010f).
Newcastle disease
Newcastle disease (ND) outbreaks were also reported during the quarter from around the world. Israel
reported two unconnected ND outbreaks in 31-day-old and 25-day-old broiler chickens in Hadarom and
Hamerkaz regions respectively, the first since June 2009 (OIE, 2010g; OIE, 2010h). Disease control
measures were put in place, including culling, vaccination and surveillance (Defra, 2010). Peru also
reported an outbreak of ND in backyard poultry during February (OIE, 2010i).
VLA, in collaboration with Defra monitors the international situation and distribution of avian notifiable
disease outbreaks. As a result, Defra currently considers there is an ongoing, low risk of introduction of
notifiable avian influenza to the UK. Influenza A viruses also continually circulate in wild bird populations
globally, and there is therefore, a continual threat of introduction to poultry. The importance for all poultry
keepers to maintain robust biosecurity measures, vigilance for clinical signs of disease and to promptly
report suspect cases of avian notifiable disease remains undiminished.
INVESTIGATORY AND ADVISORY FARM VISITS
VLA and SAC veterinarians visit farms at the request of private veterinary surgeons, to assist with the
investigation of unusual, severe or difficult disease incidents (see tables below). VLA veterinarians also
visit for statutory purposes (for example, under the Zoonoses Order to investigate outbreaks of
salmonellosis). From 2007, the VLA and SAC VS harmonised the way in which these more detailed
investigations involving visits to farms were recorded. This is why comparable data is not available for
previous years.
Table 5. Farm Investigation and Advisory Visits (Poultry) in GB – 1st Quarter
January – March
2010
2009
2008
2007
2006
VLA
SAC
Total Visits
5
9
6
15
7
2
0
N/A
N/A
N/A
7
9
N/A
N/A
N/A
CHEMICAL FOOD SAFETY INCIDENTS
The number of incidents investigated in Great Britain during the quarter is shown in Table 6. Further
details of incidents investigated by VLA are published in a quarterly report, which is available at:
http://www.defra.gov.uk/vla/reports/rep_food.htm.
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GB Avian Disease Surveillance quarterly report
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Table 6. Chemical Food Safety Incidents (Poultry) in GB – 1st Quarter
January – March
VLA
SAC
Total Incidents
2010
2009
2008
2007
2006
1
0
0
0
2
0
1
N/A
N/A
N/A
1
1
N/A
N/A
N/A
Lead poisoning
Lead poisoning was diagnosed on two occasions. One was in a 3-year-old Indian Runner duck, one of
three birds from a group of eight to show anorexia, diarrhoea, recumbency and paresis. High kidney lead
was detected (2115µmol/kg DM). A farm visit was performed, the owner was advised not to eat the eggs
and further testing on the premises was being carried out. The second incident involved one duck from a
group of twenty presenting with mucoid watery diarrhoea, malaise and a flaccid paralysis of the right leg.
Oesophageal dilatation with food present was seen at post-mortem examination, and a kidney lead value
of 1503µmol/kg DM was measured. Both sites were in known geochemical lead areas in Cumbria and
Derbyshire. Advice regarding food safety was given.
ZOONOSES - SALMONELLA
In the table below an incident is defined as ‘the first isolation and all subsequent isolations of the same
serovar or serovar and phage/definitive type combination of a particular Salmonella from an animal,
group of animals or their environment on a single premises, within a defined time period (usually 30
days).
No clinical cases of disease due to S. Enteritidis were recorded on VIDA in chickens during the quarter,
nor since 2004. No clinical cases of disease due to S. Enteritidis have been recorded on VIDA in turkeys
for several years. Sampling of chicken breeder, layer and broiler flocks and turkey breeder and
production flocks according to the requirements of the Salmonella National Control Programmes (NCP)
is ongoing. The NCP for turkeys commenced in early 2010. More details of the Salmonella NCPs can be
found on Defra’s website: http://www.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/zoonoses/ncp.htm
Table 7. The annual incidents of S. Binza and S. Orion in pheasants
2004
Binza
(total)
Orion
(total)
2005 2006 2007
2008
2009
2010
(Jan-Mar)
4
10
21
7
6
0
0
1
3
3
2
2
2
0
CROSS-SECTOR AVIAN DISEASES
Infectious Bronchitis
This quarter saw the first detections of the so-called ‘QX’ variant of Infectious Bronchitis virus (IBV) in
commercial poultry in GB following testing of swab samples by the VLA’s IBV RRT-PCR and S1
genotyping methods (http://www.defra.gov.uk/vla/labtest/Surv/AvianVirology.htm). Both cases involved
large broiler flocks of at least 25,000 birds (aged 30-days and 50-days respectively) located in the north
and east of England, with clinical histories including wasting, nephropathy and increased mortality.
Selected IBV RRT-PCR positive samples from each flock were tested by the IBV S1 genotyping method
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GB Avian Disease Surveillance quarterly report
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and sequencing results were consistent with high levels of identity (98%) with recognised European QXlike strains. Since 2007, when an IBV strain with a close relationship to the so-called Chinese QX strain
was first isolated in GB (Gough and others, 2008. Veterinary Record,162, 99-100) this IBV variant has
previously only been identified from smaller and backyard type flocks, and a similar pattern of events
was also seen in Italy (Beato and others, 2006). Hence, these types of flock appear to be a reservoir of
infection that is periodically detected in GB, but it is not known what, if any, risk pathways exist with the
commercial poultry sector. Work performed recently by the VLA and AH has also highlighted that a
complex network of contacts exists between backyard poultry flocks in GB.
Blackhead (histomonosis)
No incidents of histomonosis were recorded on VIDA in turkeys during the quarter. Blackhead has only
been recorded in turkeys on VIDA in the January-March quarter once during the past five years. This is
because the disease is now seen predominantly in small seasonal flocks being reared for the Christmas
market.
Whilst chickens are less susceptible to histomonosis than turkeys, outbreaks of disease can occur.
Furthermore, in chickens the disease shows less of a seasonal pattern and may be more related to birds
having access to Heterakis gallinarum worms and earthworms, which act as intermediate hosts for
Histomonas meleagridis. However, no incidents of the disease were recorded on VIDA during the first
quarter of 2010, but six cases have been recorded in the first quarter over the last five years.
Marek’s Disease
There was a slight increase in incidents of Marek’s disease incidents recorded on VIDA during the
quarter, but the number of incidents remained below the peak of recent years (Figure 11). The disease
remains economically important in commercial layers and broilers, and vaccination is widely practised.
The disease is also a significant cause of loss in backyard and hobby flocks. The visceral form of the
disease was recorded in 68-day old organic broilers.
Figure 11: VIDA incidents of Marek’s disease in chickens (as a percentage of diagnosable
submissions) January - March 1999-2010
(Vertical bars represent 95% confidence limits)
ENDEMIC DISEASE SURVEILLANCE
COMMERICIAL LAYERS AND LAYER BREEDERS
“Red mite” in Commercial Layers
A rise in mortality in layers aged 50 weeks on deep litter was attributed to a heavy red mite
(Dermanyssus gallinae) challenge. Submitted carcases had pale combs and pale breast muscles, and
large numbers of red mites were present on the birds and in the bags in which the carcases had been
submitted. Microscopy confirmed that the mites were red mites and not northern fowl mite
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GB Avian Disease Surveillance quarterly report
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(Ornithonyssus sylviarum). Two weeks later birds aged 25 weeks from the adjacent house died in similar
circumstances.
The red mite is the most significant parasite of layer chickens in the UK, with effects on bird welfare and
production. Control is difficult and is currently aimed at reducing the numbers of mites in the birds’
environment. The mites are prolific, being able to complete their life cycle in as little as seven days,
acaricides do not penetrate easily into its hiding places and some strains have developed resistance to
some acaricides.
Erysipelas in Commercial Layers
Acute Erysipelothrix rhusiopathiae septicaemia (“Erysipelas”) was diagnosed in a flock of 15,000 freerange birds aged 60-weeks, which had shown increased mortality over a 7-day period with losses of
around 100 birds per day over the three days prior to submission.
Erysipelas has been diagnosed, mostly in free-range flocks, in most quarters over the past two years,
and has been reported in previous AQRs with comments regarding vaccination and availability of
vaccines licensed for layers (see Vol. 12, No.4, Oct-Dec 2008 and Vol. 13, No.1, Jan-Mar 2009:
http://www.defra.gov.uk/vla/reports/docs/rep_survrep_qtlya0109.pdf). There is no longer a bivalent
vaccine for Erysipelas and Fowl cholera (Pasteurella multocida), although there is a licensed product
(inactivated
vaccine)
for
use
in
chickens,
turkeys
and
ducks
(http://www.noahcompendium.co.uk/Compendium/Overview/).
Other diseases
Two layers aged 53 weeks were submitted. One of the birds had a large urolith in one ureter, resulting in
atrophy of the kidney. The other bird had a large shell-less egg free in the abdominal cavity. The
possible involvement of a variant strain of Infectious Bronchitis virus was considered.
BROILERS AND BROILER BREEDERS
Chick Anaemia
Classical chick anaemia due to chicken infectious anaemia virus (CIAV) infection was diagnosed in a
small proportion of chicks in several broiler flocks over a period of a few weeks this quarter. This
condition usually only develops following vertical transmission of CIAV in the absence of maternal
antibody. Affected birds were slightly stunted by approx 8-10 days, but in flocks where there was
increased mortality it usually started slightly later, from around 11-12 days. At post-mortem examination
(PME) affected chicks were small for their age, markedly anaemic, with pale bone marrow and atrophy of
the thymus, spleen and bursa of Fabricius. Since the introduction of CIAV vaccination in the early 1990s,
classical Chick Anaemia resulting from vertical transmission of CIAV in the absence of maternal antibody
(mAb) has rarely been seen in the UK. Subclinical CIAV infection, due to lateral spread of the infection
once mAb levels have declined, is probably very common. The full significance of its effect on broiler
performance is not known. In a UK study, production parameters were depressed in broiler flocks which
had seroconverted to CIAV by the time of slaughter (McNulty et al., 1991. Avian Dis. 35:263-268).
However, at least two studies, in the USA and Denmark, have been unable to confirm the negative
influence of subclinical CIAV infection on production (Goodwin et al., 1993. Avian Dis. 37:542-545;
Jorgensen et al., 1995. Br. Poult. Sci. 36:3455-3463). For a recent review on clinical aspects of
immunosuppressive agents in poultry see Hoerr, F.J. (2010). Avian Dis. 54:2-15.
Incomplete seroconversion by the time of point of lay in a small number of vaccinated broiler parent
flocks was thought to have been responsible for vertical transmission of the virus and subsequent cases
of full-blown chick anaemia in this instance.
Transmissible viral proventriculitis
38-day-old broilers from a flock that was several days behind target weight for age were found to have
enlarged thickened proventriculi at PME. Histopathological examination of proventriculus confirmed
degeneration of glandular tissue and non-suppurative inflammation of several submucosal glands
consistent with so-called transmissible viral proventriculitis. This condition has been diagnosed
infrequently in UK broilers since at least the early 1990s (Randall, Avian Histopathology, 1993). The
cause of the condition in the UK is not known, though a viral infection is suspected. Recent work in the
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GB Avian Disease Surveillance quarterly report
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USA has implicated a birna-like virus distinct from the virtually ubiquitous birna virus, which causes
Infectious Bursal Disease – “Gumboro” disease. For a review of the condition see Dormitorio et al.
(2007), Avian Pathology 36:87-91.
Abdominal cellulitis
An increase in the flock incidence and condemnations at slaughter for abdominal cellulitis due to E coli
infections were seen this Quarter. This condition is often but not always associated with a history of skin
scratches over the lower abdomen and flanks. Some affected individuals also have septic arthritis and
pericarditis or polyserositis. Attention to management factors ensuring an even spread of birds
throughout the house, even feed distribution to reduce competition for feeder space and careful use of
lighting patterns to reduce overactivity and any tendency of birds to “flightiness” are possible ways of
reducing the incidence of the condition, mostly by minimising birds climbing over each other and inflicting
skin scratches.
E. coli septicaemia was considered responsible for increased mortality in uneven broiler chicks aged 5
days, with some of the dead birds small, the remainder well grown. Necropsy showed that the larger
birds had died from yolk sac infection and the small birds had lesions of kidney failure. In a separate
incident, yolk sac infection, pericarditis and perihepatitis were consistently found in broilers aged 6-8
days from a batch with increased mortality and heavy growths of E. coli were isolated from the viscera.
Gastrocnemius tendon rupture in Broiler breeders
Further cases of traumatic rupture of the gastrocnemius tendon in broiler breeder hens in the early part
of lay were seen this quarter (see also AQR Vol.13, No.4, Oct-Dec 2009
http://www.defra.gov.uk/vla/reports/docs/rep_survrep_qtlya0409.pdf). Along with peritonitis and E. coli
septicaemia in females in lay, this condition continues to be the most common reason for diagnostic
submission of this category of fowl.
The continued very low temperatures in January 2010 also affected producers resulting in additional
heating costs, increased food consumption and lower production, with ‘wet litter’, unevenness and poor
target weights reported and investigated in some broiler flocks.
TURKEYS
Swollen hocks and distended tendon sheaths over the lateral surface of the hocks were present in a
flock of 1,000 turkeys being reared as table birds. 50 birds were affected and unsuitable for slaughter.
Eyes were also described as ‘infected’. A tenosynovitis was identified grossly and positive serology to
Mycoplasma synoviae was found, but no mycoplasmas were detected by PCR.
DUCKS AND GEESE
Snowfall and icy conditions experienced in January were thought to have contributed to the deaths of 5
out of 120 ducks. Gastrointestinal tracts were empty and urate deposits were found in the carcase
suggesting birds had not been eating and drinking. Supplementary food and water was provided and
losses ceased.
Goose Parvovirus – A seasonal reminder
Since 2004, Goose Parvovirus (GPV) infection has been suspected, investigated and confirmed in
several goose flocks across Great Britain. GPV infection, also know as Derzsy’s disease or goose
plague, is a highly contagious disease of goslings and Muscovy ducklings under six weeks of age that
can cause severe losses. Goslings that are being reared for the Christmas market are typically hatched
from the early summer of each year, so if disease due to GPV infection occurs, this will typically manifest
from that time of year onwards. GPV is a not a notifiable disease, and therefore is not subject to any
statutory controls in Great Britain. Similarly, there is no recognised public health risk or significance
attached to GPV.
VLA would be very interested to hear of any suspected cases of GPV – please contact us to discuss
further. VLA Regional Laboratories have also issued this reminder in their monthly newsletters. Further
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GB Avian Disease Surveillance quarterly report
Vol 14. No. 1 Date: Jan-March 2010
information about GPV, including images of affected goslings
at: http://www.defra.gov.uk/vla/diseases/dis_goose_parvovirus.htm.
can
also
be
found
GAME BIRDS
The January to March quarter marks the end of the pheasant and partridge shooting seasons. Adult
birds have been retained through the winter in preparation for the forthcoming breeding season, and in
addition the numbers of breeding pheasants will have been supplemented by birds “caught up” in late
winter and early spring. Few disease investigations are generally carried out during this period, but three
cases of note are described below.
Respiratory disease in pheasants
A problem of loss of condition and respiratory difficulties was investigated in pheasants from a large
shooting estate. The significant findings were marked thickening of the abdominal air sacs in some of
the birds, accompanied by extensive granuloma formation in the lungs. The presence of a chronic
granulomatous pneumonia and chronic airsacculitis were confirmed by histopathology.
Ornithobacterium rhinotracheale (ORT) was confirmed in the affected lung tissue of one bird and air sac
tissue from another bird, and there was also serological evidence of Mycoplasma gallisepticum infection,
with positive antibody titres in all the birds received. ORT is rarely diagnosed in pheasants, but this was
the second case recorded in pheasants over the winter, on different estates; in both cases the disease
was characterised by airsacculitis and granulomatous pneumonia and there was evidence of concurrent
infection with other respiratory pathogens, as with Mycoplasma gallisepticum in this case.
An outbreak of conjunctivitis in pheasants retained for breeding was investigated. The birds had been
vaccinated against avian metapneumovirus (TRT) and Mycoplasma gallisepticum, which would be
amongst the potential aetiological agents of conjunctivitis. In this case Riemerella anatipestifer was
isolated from an irregularly shaped swelling below the eye in one bird. This is an unusual isolate in
pheasants, and is more commonly associated with septicaemia in ducklings and occasionally with
disease in turkeys, and it is interesting to note that turkeys had previously been on the site being finished
for the Christmas market.
Facial swelling was noted in an adult hen pheasant, causing the owner to be concerned about possible
mycoplasmosis. Necropsy identified bilateral swellings around the external ear openings and mild
swellings above the hocks were also noted. Further examination found that the facial swellings
comprised neoplastic lymphoid tissue. Similar findings have been made in pheasants from other sites in
past years – the cause of such tumours has yet to be identified but reticulo-endotheliosis virus has been
demonstrated in some of the tumours.
BACKYARD FLOCKS
Intestinal Dilation in Layers
Abnormal faeces affecting six out of eight hens, which was non-responsive to anthelmintic and anticoccidial treatments was investigated following the receipt of a cull hen. At post-mortem no evidence of
parasitism was found, but there was a generalised peritonitis associated with E. coli infection, liquid
intestinal contents and dilation of the small intestine up to a diameter of 3cm. Previous reports by VLA of
clinical signs of intestinal dilation in layers (Veterinary Record, 2005, 157, 63-64) have described poor
egg production, increased mortality, poor body condition and pale combs. This is a condition of unknown
aetiology and it has been diagnosed sporadically in free-range laying hens. Post-mortem examination is
required to make a diagnosis.
Predation
It is important to consider predator attack in cases of sudden unexplained high mortality in backyard
hens. In a recent case all eleven hens in one shed were found dead unexpectedly in the morning.
Close examination revealed punctate bite wounds on the dorsal aspect of their necks, typical of a
mustelid attack.
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