Download Haemobartonella felis

Journal of Feline Medicine and Surgery (2002) 4, 3–11
doi:10.1053/jfms.2001.0155, available online at http://www.idealibrary.com on
REVIEW ARTICLE
Haemobartonella felis: recent developments in
diagnosis and treatment
S Tasker1*, MR Lappin2
1
The Feline Centre, Clinical
Veterinary Science, University
of Bristol, Langford, Bristol
BS40 5DU, UK; 2CVMBS-VTH,
Clinical Sciences, Colorado State
University, 300 W. Drake Road,
Fort Collins, CO 80523, USA
Date accepted 1 October 2001
Haemobartonella felis is a pleomorphic uncultivated wall-less haemotrophic
bacterial parasite. Phylogenetic analysis of 16S rRNA gene sequences from a
number of isolates of H felis has demonstrated that these bacteria are most
closely related to species in the genus Mycoplasma, and Haemobartonella and
related organisms are currently being reclassified as Mollicutes. Diagnosis by
cytological examination of blood smears has been problematic, but recent
molecular studies have led to the development of sensitive polymerase chain
reaction (PCR) assays for diagnosis. Such studies have also resulted in the
recognition of two distinct strains of H felis, which are divided into different
groups based on phylogenetic analysis. This evolutionary divergence between
strains is accompanied by differences in pathogenecity. This review discusses
new developments in the diagnosis and treatment of H felis, focusing on the
use of, and interpretation of, PCR assays.
© 2002 ESFM and AAFP
I
n 1942 Clark described an eperythrozoon
infection in an anaemic cat in South Africa
naming the species Eperythrozoon felis. Flint &
Moss (1953) later described a similar organism
causing an infectious anaemia in cats in the USA.
In 1955, Flint & McKelvie suggested that this
organism be named Haemobartonella felis.
Haemobartonella felis is now recognised worldwide (Anderson & Charleston 1967, Bedford
1970, Bobade & Akinyemi 1981, Clark 1942,
Espada et al 1991, Flagstad & Larsen 1969,
Hatakka 1972, Maede et al 1974, Manusu 1961,
Mrljak et al 1995, Prieur 1960, Seamer & Douglas
1959, Théry 1966) although studies describing
the prevalence of infections in cats in different
parts of the world have been sparse. Despite it
being a major cause of anaemia in cats there is
still a paucity of information available regarding
its epidemiology and the disease it causes. One
of the major factors limiting the investigation of this organism is that it has not yet been
successfully cultivated outside the host.
However, recent molecular studies have
advanced our understanding of the nature and
*Corresponding author E-mail: [email protected]
1098-612X/02/010001+09 $35.00/0
pathogenicity of this organism. Analysis of the
16S rRNA gene of several H felis isolates has led
to the discovery of its evolutionary relatedness
to members of the Mollicutes rather than the
Rickettsiales (Johansson et al 1999, Neimark &
Kocan 1997, Rikihisa et al 1997) and reclassification of the organism has been recommended. In
situ hybridisation studies (Berent et al 2000) have
physically linked H felis DNA sequences to areas
of known cellular pathology on feline erythrocytes. Similarly the presence of H felis DNA
coincides with experimental infection (Berent
et al 1998) and the amount of DNA is correlated
with the number of organisms present in the
blood (Cooper et al 1999). These molecular findings have proven that H felis is the cause of feline
infectious anaemia. Recent molecular work also
documents the existence of different strains
(Berent et al 1998, Foley et al 1998, Messick et al
1998, Rikihisa et al 1997) that may ultimately
prove to be different Haemobartonella species.
Since H felis cannot be cultured, diagnosis of
infection until recently was primarily based on
cytological identification of organisms on the
surface of red blood cells. However, there are
various factors resulting in false positive and
© 2002 ESFM and AAFP
4
S Tasker, MR Lappin
Diagnosis of H felis infection
Examination of blood smears
Fig 1. Wright–Giemsa stained blood smear (original magnification ×1000) showing small epicellular coccoid and rod
shaped H felis bodies on approximately 50% of erythrocytes.
false negative results with this method. The
polymerase chain reaction (PCR) is now the test
of choice for the diagnosis of H felis infection
and is commercially available in several laboratories in North America. The availability of a
sensitive diagnostic test has enabled more accurate studies to be performed to assess success of
treatment as well. This review will focus on
recent advances in characterisation of the H felis
strains as well as the diagnosis and treatment of
haemobartonellosis.
The most commonly used method to definitively
diagnose H felis is demonstration of organisms
on the surface of erythrocytes by microscopic
examination of a good quality blood smear. Butt
provides an excellent review in the preparation
and staining of diagnostic blood smears (Butt
1990). A number of Romanowsky-type blood
stains can be used including Giemsa, May–
Grunwald–Giemsa, Wright, and Wright–Giemsa
stains. The organism is typically found around
the periphery of the erythrocyte, and may be
found singly, in pairs, or in chains with severe
infestation (Figs 1 and 2). Very occasionally
organisms may lie free of the erythrocytes
because of detachment from cells.
False positive diagnoses are sometimes made
when artefacts caused by improper drying or
fixation and stain precipitation are confused with
the organism. The use of fresh filtered stain
solutions is imperative. Stain precipitate is
usually found above the plane of focus of the
erythrocytes and is more densely staining and
larger than H felis organisms. Refractile artefacts
occur when moisture adheres to the cells on the
film and these tend to have irregular borders and
Fig 2. Wright-Giemsa stained blood smear (original magnification ×400) showing H felis bodies on approximately 65% of
erythrocytes. Ring forms of H felis are visible (large arrows). Larger and more densely staining Howell–Jolly bodies can be
seen (small arrows) for comparision.
Recent developments in Haemobartonella felis
appear colourless when the erythrocytes are in
focus. H felis must also be distinguished from
other feline erythrocytic inclusions. Howell–Jolly
bodies (Fig 2) are erythrocytic nuclear remnants
and can be differentiated from H felis by
their larger size (around 1–2 m in diameter).
Pappenheimer bodies are aggregates of iron
accumulation and appear as lightly staining
small blue granules. Acridine orange (AO) and
direct fluorescent antibody staining methods are
reported to be more sensitive than standard
Romanowsky stains for demonstrating H felis
(Berent et al 1998, Bobade & Nash 1987, Small &
Ristic 1967). However, both these techniques are
limited by the need for a fluorescent microscope.
AO combines specifically with nucleic acids,
and organisms appear bright orange with an
undertone of yellow green. Non-specific
fluorescence can also give false positive results
and Howell–Jolly bodies, which also stain with
AO, must be differentiated from H felis (Harvey
& Gaskin 1977).
False negative diagnoses are also a major
problem when blood smears are relied upon
for the diagnosis of H felis infection. While
parasitaemia can be extremely heavy during
acute infection, the clearance of parasites from
the blood can be rapid resulting in negative
cytological findings within a few hours (Alleman
et al 1999, Harvey & Gaskin 1977). This cyclical
parasitaemia means that the absence of
organisms on examination of a blood smear does
not definitively exclude a diagnosis of haemobartonellosis. These factors contribute to the
poor sensitivity of cytopathology in the diagnosis of haemobartonellosis. In a recent experimental study that compared cytopathology and
PCR in experimentally inoculated cats, the detection rates were 37.5% and 100% respectively in
samples collected after inoculation (Westfall et al
2001). The preparation of multiple fresh blood
smears over a period of 24 h or over the course of
a few days may increase the chance of obtaining
a positive diagnosis. Sample handling is also
important. High concentrations of EDTA anticoagulant have been reported to detach
organisms from the erythrocyte surface within a
couple of hours (Alleman et al 1999), making
identification of organisms on blood smears
extremely difficult. It would therefore seem
prudent to prepare blood smears immediately
after blood collection using non-anticoagulated
blood or use heparin which is not thought
to result in the organisms being dislodged
(Alleman et al 1999).
5
Serology
Results of Western immunoblotting showed that
some H felis antigens are recognised as early as
14 days after infection (Alleman et al 1999). In
one study of cats experimentally inoculated
with two H felis strains, antibodies were
usually detected by indirect immunofluorescent
antibody assay by 21 days post-infection and
persisted for at least 6 months, well after clinical
disease had resolved (Foley et al 1998). Since
antibodies can be demonstrated in subclinically
infected carrier cats as well as in anaemic cats, a
positive serological test does not equate with the
presence of clinical disease. Sera generated
against one strain of H felis did not detect organisms of another strain suggesting that antigenic
variation exists (Foley et al 1998), and such
antigenic variation may actually play a role in
the development of cyclical parasitaemia in
infected cats. If an antibody assay could be
developed that detected only antibodies against
pathogenic strains, it may have diagnostic value.
Serological testing is not currently available
commercially.
Polymerase chain reaction
The polymerase chain reaction (PCR) is a powerful and sensitive molecular technique whereby
low numbers of specific fragments of DNA are
amplified exponentially to detectable levels. A
review of the principals of the PCR test has
recently been published (Lutz et al 1999). It is
claimed that as few as 52 H felis organisms can be
detected by PCR on blood (Cooper et al 1999).
Various American studies have amplified
H felis 16S rRNA DNA sequences from infected
cats and these PCR products have been sequenced (Berent et al 1998, Foley et al 1998,
Messick et al 1998, Rikihisa et al 1997) resulting
in the recognition of genetically distinct strains of
H felis. The Ohio (large) strain and the California
(small) strain have been most extensively investigated by molecular methods (Berent et al 1998,
Foley et al 1998, Jensen et al 2001, Westfall et al
2001). Recently sequencing of a United Kingdom
strain of H felis (named the Birmingham strain)
revealed near identity to the California small
strain (Tasker et al 2001a) confirming that strains
similar to this American strain are present in the
Old World. Recently work in the UK (Tasker et al
2001b) has also confirmed the presence of H felis
strains very similar to the American large form
(Figure 3). Further work is required to determine
6
S Tasker, MR Lappin
Fig 3. Four percent agarose gel showing PCR products
obtained by amplification of DNA extracted from feline
blood samples. PCR protocol used courtesy of Heska
Corporation, Fort Collins, Colorado, USA. S, suspected case
from United Kingdom; Hfsm, positive control sample
infected with H felis small form; Hflg, positive control
sample infected with H felis large form; Mr, DNA molecular
weight markers; S1 is infected with H felis small form and S2
and S5 are infected with H felis large form. Cases S3 and S4
are PCR negative for H felis.
whether other strains exist and to document any
worldwide geographical variation. Phylogenetic
analysis of the 16S rRNA DNA sequences of
the H felis strains currently available reveals
the evolutionary divergence of these organisms
(Johansson et al 1999, Neimark & Kocan 1997,
Rikihisa et al 1997, Tasker et al 2001a). Figure 4
shows a phylogenetic tree constructed from 1000
sets of bootstrapped data by the neighbourjoining method of Saitou & Nei (1987) following
alignment of 16S rRNA gene sequences using
CLUSTAL W (Version 1.6, EMBL) according
to the method of Thompson et al (1994). The
California and Birmingham H felis strains form a
monophyletic group that is more closely related
to the Eperythrozoon organisms E suis and E
wenyonii than other Haemobartonella spp. Conversely, the Ohio/Florida, Illinois and Oklahoma
H felis strains all share close homology and are
more closely related as a group to H muris and
H canis than to the California and Birmingham
strains. The division, by phylogeny, of H felis
strains into two divergent groups suggests at
least two different species of Haemobartonella
exist. The divergence determined among H felis
strains is reflected in phenotypic differences
between them. Morphologically, on Wright–
Giemsa stained blood smears, the large/Ohio
form is said to be approximately twice as large
and substantially darker than the small/
California form (Foley et al 1998), although
the strains cannot be reliably distinguished by
appearance alone.
Important from a clinical standpoint are the
differences in pathogenicity apparent between
the strains in the few studies performed to date.
Experimental infection of cats with two different
isolates of the California strain (Foley et al 1998,
Westfall et al 2001) resulted in minimal clinical
signs and anaemia was not usually induced.
Preliminary findings suggest that the genetically
related Birmingham strain is also of low pathogenicity (Tasker et al 2001a). Conversely experimental infection with the Ohio strain often
results in a severe, sometimes fatal, haemolytic
anaemia (Berent et al 1998, Foley et al 1998,
Westfall et al 2001). Additionally, experimental
inoculation of large form of H felis in cats
already infected with the small form appeared to
result in more severe clinical disease than the
large form alone (Westfall et al 2001). This finding may be because prior infection with one
Haemobartonella strain predisposes to immunemediated disease when cats become infected
with another strain. The nature of such superinfections and characterisation of the host’s
immune response to infection have not yet been
investigated.
At this time, it is impossible to make definitive
statements concerning pathogenicity of the
H felis strains. Since H felis cannot be cultivated
or accurately counted, it cannot be determined if
experimentally inoculated cats received similar
doses of organism which may have influenced
clinical findings. Additionally, most of the experimental infections with defined strains to date
have used intravenous inoculation (Berent et al
1998, Messick et al 1998, Westfall et al 2001).
Natural routes of transmission of H felis have not
yet been defined and it is possible that route of
transmission (including possible vectors) may
affect pathogenicity.
Recently, Jensen and colleagues (Jensen et al
2001) developed a PCR assay that is able to
detect and distinguish both the small and large
strains of H felis and applied the assay to blood
from 220 American cats. The overall prevalence
of H felis infection was 19.5%. Anaemic cats were
more likely to be infected with either the large
strain or both the small and large strains, than
non-anaemic cats. This supports the experimental findings that infection with the large strain or
dual infection results in more severe clinical
disease (Westfall et al 2001). A recent UK study
(Tasker et al 2001b) based on the same PCR assay
reported an similar prevalence of H felis infection
Recent developments in Haemobartonella felis
7
0.03
E coli
E wenyonii
329
E erythrodidelphis
588
H felis
Birmingham
1000
1000
H felis
California
E suis
999
H muris
H felis
Oklahoma
496
993
501
H felis
Illinois
1000
1000
H felis
Ohio-Florida
H canis
M fastidiosum
1000
M cavipharyngis
M felis
Fig 4. Phylogenetic tree comparing the available Haemobartonella felis sequences and the related organisms Eperythrozoon
wenyonii, Eperythrozoon erythrodidelphis, Eperythrozoon suis, Haemobartonella muris, Haemobartonella canis, Mycoplasma
fastidiosum, Mycoplasma cavipharyngis and Mycoplasma felis. Escherichia coli is shown for reference. The numbers at each node
indicate the number of times the groups to the right of the node occurred among 1000 trees. The bar represents the mean
number of differences per site.
8
S Tasker, MR Lappin
(18%) but very few cats were infected with the
large strain precluding statistical evaluation of
an association between the large strain and anaemia. Small strain infection in the UK was common and was not associated with the presence of
anaemia. Further studies are required to determine whether geographical variation in the
prevalence of H felis infection, including the
different strains, exists.
PCR was shown to be more sensitive than
examination of blood smears in the detection of
H felis in several studies. As previously discussed, Westfall et al (2001) found that only
37.5% of samples were positive on cytopathology
after experimental infection compared to 100%
positivity with PCR. H felis can be detected by
PCR as early as 8 days post-infection and cats
remain PCR positive until antibiotic treatment is
started. Cats then remain negative by PCR for
the duration of antibiotic treatment, but become
positive again between 3 days and 5 weeks after
completion of the antibiotic course (Berent et al
1998, Foley et al 1998). Blood samples for H felis
PCR should therefore not be submitted during
antibiotic treatment. Subclinically infected cats
remain PCR positive for at least 6 months, long
after clinical signs of disease have resolved.
Additionally, 14.5% of normal, naturally exposed
cats in a US study (Jensen et al 2001) and 10% of
healthy cats in a UK study (Tasker et al 2001b)
were positive for H felis by PCR. Thus, it is
apparent that a positive PCR result does not
equate with clinical disease, making interpretation of results problematic. A positive PCR
result should be interpreted in line with the
strain identified, the haematological findings and
clinical signs reported.
Clinical signs and haematology features
Previous reports that uncomplicated H felis
infection caused few or no clinical signs (Bobade
et al 1988, Seamer & Douglas 1959) may have
reflected infection with an H felis small strain of
low pathogenicity (Foley et al 1998). Chronically
infected cats are usually clinically normal (Berent
et al 1998). In other studies, a severe haemolytic
anaemia occurred in all infected cats (Flint et al
1958, Foley et al 1998), most probably due to a
pathogenic large strain. Clinical signs seen in ill
cats are non-specific but include those typically
associated with anaemia such as pallor and
lethargy, as well as anorexia, weight loss and
depression. Intermittent pyrexia is often seen,
particularly in the acute stages of the disease.
Splenomegaly and lymphadenopathy may
occur, reflecting extramedullary haematopoiesis.
Icterus, due to haemolysis, is occasionally seen.
H felis infection typically causes a regenerative
anaemia with reticulocytosis, anisocytosis,
macrocytosis and polychromasia. The severity of
anaemia depends on the stage of infection but
the haematocrit usually falls to less than 20%,
with average values of 15–18% reported (Foley et
al 1998, VanSteenhouse et al 1993). Normoblasts
may also be visible and, although these can be a
feature of diseases which are not associated with
regenerative anaemias, H felis was found to be
the most common cause of normoblastaemia
in a recent retrospective study (Hammer &
Wellman 1999). Non-regenerative anaemias due
to haemobartonellosis have also been reported
(VanSteenhouse et al 1993).
Treatment
Haemobartonella spp are sensitive to tetracyclines
which specifically inhibit protein synthesis in
procaryotes. Tetracycline and oxytetracycline can
both cause drug-induced pyrexia (Wilkinson
1968) in cats and require three times daily
dosing, which may be problematic. The preferred
tetracycline derivative used is doxycycline
due to fewer side effects and less frequent
dosing. The recommended doxycycline dose is
5–10 mg/kg per os once daily. Therapy should
be continued for 14 to 21 days depending on
response to treatment. As mentioned above, PCR
has demonstrated that although the tetracyclines
are effective for the treatment of anaemia, treatment does not eliminate the causal organism
(Berent et al 1998, Foley et al 1998). Enrofloxacin
has been recommended by some (Winter 1993)
for the treatment of haemobartonellosis at a dose
of 10 mg/kg per os daily for at least 14 days.
Fluoroquinolones are said to have activity
against mycoplasmal organisms but further
study into their effectiveness against H felis is
warranted before a recommendation can be
made. The macrolide azithromycin, which is
effective for the treatment of several Mycoplasmaassociated syndromes in humans, was recently
found to be ineffective in the treatment of haemobartonellosis at one dose regime (15 mg/kg per
os twice daily) (Westfall et al 2001).
The anaemia induced by H felis is thought to
be, in part, immune-mediated so glucocorticoids
may be indicated (VanSteenhouse et al 1993). It
is important that concurrent diseases such as
toxoplasmosis, which could be exacerbated by
Recent developments in Haemobartonella felis
the use of glucocorticoids, are ruled out first
(Hoskins & Barta 1984). Some advocate the use
of glucocorticoids only if the anaemia is pronounced or acute in onset and/or autoagglutination is present (Carney & England 1993). The
recommended dose of prednisolone is 2 mg/kg
per day per os, alongside antibiotic therapy, with
a tapering of dosage over 3 weeks. The value of
glucocorticoids in the treatment of H felis has
not yet been evaluated. However, cats with
experimentally induced haemobartonellosis
have apparently responded to tetracycline
derivatives (with or without supportive treatment) without the use of glucocorticoids (Berent
et al 1998, Foley et al 1998).
Supportive care including whole blood transfusion may be required in severely anaemic cats.
Cats tolerate anaemia well but if the anaemia is
severe (haematocrit less than 12%) or if the PCV
has dropped rapidly, a blood transfusion may be
necessary. Feline blood transfusions should only
be performed with typed or cross-matched
recipient and donor blood to avoid potentially
fatal blood transfusion reactions.
It has not been definitely documented that
H felis is transmitted by fleas but it has been
suggested that they are a major vector for H felis
transmission. Since it is known that H felis can be
transmitted by inoculation of infected blood, it
seems wise to recommend thorough flea control
to potentially lessen the risk of a cat acquiring
haemobartonellosis.
Based on studies to date, several recommendations concerning testing methods and when to
administer antibiotics with anti-Haemobartonella
activity can be made.
(1) If a cat has clinical findings consistent with
haemobartonellosis and H felis is detected cytologically or DNA is detected by PCR (either
strain), treatment is indicated.
(2) If cytology is the only test available and
is negative in a cat with a high index of
suspicion for haemobartonellosis (such as
unexplained haemolytic anaemia), the cat should
be treated due to a high incidence of false
negative cytological results.
(3) In experimental studies, DNA can usually be
detected by PCR prior to clinical signs of disease.
Thus, if PCR results on blood collected prior to
treatment are negative, the cat probably does not
have haemobartonellosis and other differential
diagnoses should be considered.
(4) Since H felis can be transmitted by blood, and
cytology is commonly falsely negative in chroni-
9
cally infected cats, all blood donor cats from
areas where haemobartonellosis occurs, should
be screened by PCR if possible.
(5) Treatment of healthy cats is not recommended at this time since no drug or protocol
have been shown to clear the body of the
organism.
(6) The currently recommended first line treatment is doxycycline at a dose of 5–10 mg/kg per
os once daily for 14 to 21 days depending on
response to treatment.
Conclusions
In recent years molecular studies have suggested
reclassification of H felis into the Mollicutes family and enabled the development of diagnostic
PCR assays. The discovery of different H felis
strains which vary so greatly in pathogenicity
means that the interpretation of a positive PCR is
not straight forward, and confirming that H felis
is the cause of clinical disease is difficult. In the
future, research should focus on looking into the
existence of additional H felis strains and how
effective PCR is in detecting different strains, and
determining whether geographical variation in
prevalence of different strains exists. The pathogenesis of such strains also needs further investigation, in particular with respect to interaction
with other feline diseases, and the host response
to H felis infection.
Addendum
Since this article was submitted for publication
(26 February 2001), the official reclassification of
H felis within the genus Mycoplasma has been
proposed in two reports. It is suggested that the
small strains (California and Birmingham) are
renamed as ‘Candidatus Mycoplasma haemominutum’ whilst the large strains (Ohio/
Florida, Illinois and Oklahoma) are renamed
as ‘Candidatus Mycoplasma haemofelis’. The
Candidatus classification indicates that this is a
provisional status for the organism until further
phenotypic and genotypic information is
available.
Foley JE, Pedersen NC (2001) ‘Candidatus
Mycoplasma haemominutum’, a low-virulence
epierythrocytic parasite of cats. International
Journal of Systematic and Evolutionary Microbiology
51, 815–817.
Neimark H, Johansson KE, Rikihisa Y, Tully JG
(2001) Proposal to transfer some members of
the genera Haemobartonella and Eperythrozoon to
10
S Tasker, MR Lappin
the genus Mycoplasma with descriptions of
‘Candidatus Mycoplasma haemofelis’, ‘Candidatus
Mycoplasma haemomuris’, ‘Candidatus Mycoplasma haemosuis’ and ‘Candidatus Mycoplasma
wenyonii’. International Journal of Systematic and
Evolutionary Microbiology, 51, 891–899.
Acknowledgements
Dr CR Helps of the University of Bristol is
thanked for his help with the construction of the
phylogenetic tree. ST is part funded by the Royal
College of Veterinary Surgeons Trust Fund.
References
Alleman AR, Pate MG, Harvey JW, Gaskin JM, Barbet AF
(1999) Western immunoblot analysis of the antigens
of Haemobartonella felis with sera from experimentally
infected cats. Journal of Clinical Microbiology 37, 1474–1479
Anderson DC, Charleston WAG (1967) Haemobartonella felis.
New Zealand Veterinary Journal 15, 47
Bedford PG (1970) Feline infectious anaemia in the London
area. Veterinary Record 87, 305–310
Berent LM, Messick JB, Cooper SK (1998) Detection of
Haemobartonella felis in cats with experimentally induced
acute and chronic infections, using a polymerase chain
reaction assay. American Journal of Veterinary Research 59,
1215–1220
Berent LM, Messick JB, Cooper SK, Cusick PK (2000) Specific
in situ hybridisation of Haemobartonella felis with a DNA
probe and tyramide signal amplification. Veterinary
Pathology 37, 47–53
Bobade PA, Akinyemi JO (1981) A case of haemobartonellosis in a cat in Ibadan. Nigerian Veterinary Journal 10, 23–25
Bobade PA, Nash AS (1987) A comparative study of the
efficiency of acridine orange and some Romanowsky
staining procedures in the demonstration of Haemobartonella felis in feline blood. Veterinary Parasitology 26,
169–172
Bobade PA, Nash AS, Rogerson P (1988) Feline haemobartonellosis: clinical, haematological and pathological
studies in natural infections and the relationship to infection with feline leukaemia virus. Veterinary Record 122,
32–36
Butt MT (1990) Diagnosing erythrocytic parasitic diseases in
cats. Compendium of Continuing Education for the Practising
Veterinarian 12, 628–638
Carney HC, England JJ (1993) Feline hemobartonellosis.
Veterinary Clinics of North America—Small Animal Practice
23, 79–90
Clark R (1942) Eperythrozoon felis (sp. Nov) in a cat. Journal of
the South African Veterinary Medical Association 13, 15–16
Cooper SK, Berent LM, Messick JB (1999) Competitive,
quantitative PCR analysis of Haemobartonella felis in the
blood of experimentally infected cats. Journal of
Microbiological Methods 34, 235–243
Espada Y, Prats A, Albo F (1991) Feline haemobartonellosis.
Veterinary International 3, 35–40
Flagstad A, Larsen SA (1969) The occurrence of feline infectious anaemia in Denmark. Nordisk Veterinaer Medicin 21,
129–141
Flint JC, McKelvie DH (1955) Feline Infectious Anaemia —
Diagnosis and Treatment. In 92nd Annual Meeting of the
American Veterinary Medical Association, pp. 240–242.
Minneapolis
Flint JC, Moss LC (1953) Infectious anaemia in cats. Journal of
the American Veterinary Medical Association 122, 45–48
Flint JC, Roepke MH, Jensen R (1958) Feline infectious
anaemia. I. Clinical aspects. American Journal of Veterinary
Research 19, 164–168
Foley JE, Harrus S, Poland A, Chomel B, Pedersen NC (1998)
Molecular, clinical, and pathologic comparison of two
distinct strains of Haemobartonella felis in domestic cats.
American Journal of Veterinary Research 59, 1581–1588
Hammer AS, Wellman M (1999) Leukoerythroblastosis and
normoblastemia in the cat. Journal of the American Animal
Hospital Association 35, 471–473
Harvey JW, Gaskin JM (1977) Experimental feline haemobartonellosis. Journal of the American Animal Hospital
Association 13, 28–38
Hatakka M (1972) Haemobartonellosis in the domestic cat.
Acta Veterinaria Scandanavica 13, 323–331
Hoskins JD, Barta O (1984) Concurrent Haemobartonella
felis and Toxoplasma gondii infections in a cat. Veterinary
Medicine: Small Animal Clinician 79, 633–637
Jensen WA, Lappin MR, Kamkar S, Reagen WJ (2001) Use of
a polymerase chain reaction assay to detect and differentiate two strains of Haemobartonella felis infection in
naturally infected cats. American Journal of Veterinary
Research 62, 604–608
Johansson KE, Tully JG, Bolske G, Pettersson B (1999)
Mycoplasma cavipharyngis and Mycoplasma fastidiosum, the
closest relatives to Eperythrozoon spp. and Haemobartonella
spp. FEMS Microbiology Letters 174, 321–326
Lutz H, Leutenegger C, Hofmann-Lehmann R (1999) The
role of polymerase chain reaction and its newer developments in feline medicine. Journal of Feline Medicine and
Surgery 1, 89–100
Maede Y, Hata R, Shibata H, Niiyama M, Too K, Sonoda M
(1974) Clinical observation on 6 cases of feline infectious anaemia. Journal of the Japanese Veterinary Medical
Association 27, 267–272
Manusu HP (1961) Infectious feline anaemia in Australia.
Australian Veterinary Journal 37, 405
Messick JB, Berent LM, Cooper SK (1998) Development and
evaluation of a PCR-based assay for detection of Haemobartonella felis in cats and differentiation of H felis from
related bacteria by restriction fragment length polymorphism analysis. Journal of Clinical Microbiology 36, 462–466
Mrljak V, Modric Z, Bedrica L, Tudja M, Curic S, Stanin D
(1995) Haemobartonella felis as a cause of infectious
anaemia in a cat in Croatia. Kleintierpraxis, 403–408
Neimark H, Kocan KM (1997) The cell wall-less rickettsia
Eperythrozoon wenyonii is a Mycoplasma. FEMS Microbiology
Letters 156, 287–291
Prieur WD (1960) Beitrag zur infektiösen anämie der Katze.
Kleintier praxis 5, 87–89
Rikihisa Y, Kawahara M, Wen B, Kociba G, Fuerst P,
Kawamori F, Suto C, Shibata S, Futohashi M (1997)
Western immunoblot analysis of Haemobartonella muris
and comparison of 16S rRNA gene sequences of H.
muris, H felis, and Eperythrozoon suis. Journal of Clinical
Microbiology 35, 823–829
Saitou N, Nei M (1987) The neighbour-joining method:
a new method for reconstructing phylogenetic trees.
Molecular Biology & Evolution 4, 406–425
Recent developments in Haemobartonella felis
Seamer J, Douglas SW (1959) A new blood parasite of British
cats. Veterinary Record 71, 405–408
Small E, Ristic M (1967) Morphologic features of Haemobartonella felis. American Journal of Veterinary Research 28,
845–851
Tasker S, Helps CR, Belford CJ, Birtles RJ, Day MJ, Sparkes
AH, Gruffydd-Jones TJ, Harbour DA (2001a) 16S rDNA
comparison demonstrates near identity between a United
Kingdom Haemobartonella felis strain and the American
California strain. Veterinary Microbiology 81, 73–78
Tasker S, Gruffydd-Jones TJ, Jensen WA, Lappin MR (2001b)
Prevalence and Molecular Analysis of Haemobartonella felis
strains in the United Kingdom. In 11th Congress of the
European Society of Veterinary Internal Medicine, pp. 112.
Dublin, Ireland
Théry A (1966) Un foyer d’hémobartonellose féline à Paris.
Recueil de Medecine Veterinaire 142, 1163–1166
11
Thompson JD, Higgins DG, Gibson TJ (1994) CLUSTAL W:
improving the sensitivity of progressive multiple
sequence alignment through sequence weighting,
position-specific gap penalties and weight matrix choice.
Nucleic Acids Research 22, 4673–4680
VanSteenhouse JL, Millard JR, Taboada J (1993) Feline
haemobartonellosis. Compendium of Continuing Education
for the Practising Veterinarian 15, 535–545
Westfall DS, Jensen WA, Reagan WJ, Radecki SV, Lappin MR
(2001) Inoculation of two genotypes of Haemobartonella
felis (California and Ohio variants) to induce infection in
cats and the response to treatment with azithromycin.
American Journal of Veterinary Research 62, 687–681
Wilkinson GT (1968) A review of drug toxicity in the cat.
Journal of Small Animal Practice 9, 21–32
Winter RB (1993) Using quinolones to treat haemobartonellosis. Veterinary Medicine, 306–308