Feline haemobartonellosis: clinical, haematological and pathological studies in natural infections and the relationship to infection with feline leukaemia virus

Haemobartonella felis infection was demonstrated in 38 cats which could be divided into four groups as follows: group A, feline leukaemia virus (FeLV) free cats with H felis infection alone; group B, FeLV free cats with H felis infection and other clinical conditions; group C, FeLV positive cats with H felis infection but no clinical manifestation of FeLV related or any other intercurrent disease; and group D, FeLV positive cats with H felis infection and clinical manifestations of FeLV related or other diseases. Cats in group A were healthy carriers of the infection and none was anaemic, whereas some in group B had clinical haemobartonellosis and anaemia. This anaemia was mainly mild, normocytic and normochromic. Most of the cats in group C and all in group D were more severely ill and anaemic, the anaemia usually being macrocytic and hypochromic. Splenomegaly occurred only in groups C and D. Treatment with tetracyclines did not eliminate H felis from any of the cats and blood transfusions were ineffective in promoting long term recovery from anaemia in cats with intercurrent H felis and FeLV infections. The findings in the cats in groups C and D were further compared with those in a fifth group of cats which were infected with FeLV but free of H felis.     

Use of a polymerase chain reaction assay to detect and differentiate two strains of Haemobartonella felis in naturally infected cats

OBJECTIVE: To develop a polymerase chain reaction (PCR) assay that detects and differentiates the Ohio strain of Haemobartonella felis (H. felis-OH) and the California strain of H. felis (H. felis-CA) and to apply the assay to blood samples from cats with and without suspected haemobartonellosis (suspect and control cats, respectively). SAMPLE POPULATION: 220 blood samples were examined; 82 were from suspect cats, and 138 were from control cats. PROCEDURE: A PCR assay was designed to detect and differentiate H. felis-OH and H. felis-CA. RESULTS: On the basis of PCR assay results, the overall prevalence of H. felis infection was 19.5% (43/220). Suspect cats (28.0%; 23/82) were significantly more likely than control cats (14.5%; 20/138) to be H. felis infected. Significantly greater numbers of suspect cats were H. felis-OH infected (12.2%, 9/82) or H. felis-OH and H. felis-CA infected (4.9%, 4/82) than control cats (0% [0/138] and 0.7% [1/138], respectively). Significantly more anemic cats were H. felis-OH infected (14.3%; 4/28) or H. felis-OH and H. felis-CA infected (7.1%; 2/28) than nonanemic cats (2.3% [3/128] and 0.8% [1/128], respectively). The PCR assay was more accurate than cytologic examination for detection of H. felis. CONCLUSIONS AND CLINICAL RELEVANCE: Haemobartonella felis infections are more common in cats than previously recognized. Haemobartonella felis-OH is apparently more pathogenic than H. felis-CA. The PCR assay is more accurate than cytologic examination for detection of H. felis infection and is an effective clinical tool for the detection and differentiation of both H. felis strains known to infect cats.     

Molecular detection and characterization of Haemobartonella felis in domestic cats in Japan employing sequence-specific polymerase chain reaction (SS-PCR)

A novel PCR assay was developed in order to examine the prevalence of Haemobartonella felis (H. felis) in Japanese domestic cats and which was able to differentiate of the Ohio strain and the California strain of H. felis. Blood samples from a total of 21 cats suspected of having haemobartonellosis were examined employing a novel PCR assay and demonstrated positive results in 18 cats which was confirmed by cytological examination of blood smears. Four out of 18 positive cats (22%) were infected with the California strain, whilst the other 12 cats (67%) were infected with the Ohio strain and two animals (11%) were infected with both strains. As most of the cats with moderate to severe anemia were infected with the Ohio strain, it is suggested that the most prevalent strain of H. felis in Japanese domestic cats might be the Ohio strain. In the present study, it was thought that molecular detection and characterization of H. felis may provide valuable information regarding the severity and prognosis of this illness.     

Haemobartonellosis in the Domestic Cat

Post-mortem examination of two cases of natural Haemobartonella felis infection in the cat is reported. In both cases haemobartonellosis was confirmed on blood smears from the diseased animals. The most noticeable macroscopic finding was a pronounced general anemia.The microscopic examination revealed hyperplasia of the bone marrow and a moderate extramedullary hematopoiesis in case 1 and in case 2 a reduction of the M/E index in the bone marrow.Keyword: haemobartonellosis, Haemobartonella felis, Eperythrozoon felis, feline infectious anemia, blood diseases, anemia     

Effect of preexisting FeLV infection or FeLV and feline immunodeficiency virus coinfection on pathogenicity of the small variant of Haemobartonella felis in cats

OBJECTIVE: To investigate the effects of preexisting FeLV infection or FeLV and feline immunodeficiency (FIV) coinfection on the pathogenicity of the small variant of Haemobartonella felis (Hfsm, California variant) in cats. ANIMALS: 20 FeLV infected, 5 FeLV-FIV coinfected, and 19 retrovirus-free cats. PROCEDURES: A client-owned cat, coinfected with FeLV and Hfsm, was the source for Hfsm. Inoculum 1 (FeLV free) was obtained by passage of source Hfsm through 4 FeLV-resistant cats. Inoculum 2 was obtained by further passage of Hfsm (inoculum 1) through 2 specific pathogen-free cats. RESULTS: A mild-to-moderate anemia started 21 days after inoculation, with its nadir occurring at 35 to 42 days after inoculation. Infection with Hfsm induced greater decrease in hemoglobin concentration in FeLV infected cats, compared with retrovirus free cats. Reticulocytosis, macrocytosis, and polychromasia of erythrocytes developed in anemic cats regardless of retrovirus infection status. Mean neutrophil counts decreased during the hemolytic episode. For most cats, the anemia was transient. Four FeLV infected cats, 1 of which was also FIV infected, developed fatal FeLV-associated myeloproliferative diseases. Of the surviving cats, 8 died over the next 24 months from other FeLV-related diseases. Hemolysis did not recur after the initial episode. Inoculum 1 induced more severe anemia than inoculum 2. CONCLUSIONS AND CLINICAL RELEVANCE: Our results support the clinical observation that cats coinfected with FeLV and H felis develop more severe anemia than cats infected with H felis alone. Infection with Hfsm may induce myeloproliferative disease in FeLV infected cats. The small variant of H felis may lose pathogenicity by passage through FeLV-free cats.     

Inoculation of two genotypes of Hemobartonella felis (California and Ohio variants) to induce infection in cats and the response to treatment with azithromycin

OBJECTIVES: To describe clinical and laboratory findings associated with cats experimentally infected by inoculation with the 2 recognized genotypes of Hemobartonella felis (small variant, Hfsm; large variant, Hflg) and to determine the response of cats to treatment with azithromycin. ANIMALS: 18 young adult domestic shorthair cats of both sexes. PROCEDURES: Cats were inoculated with H felis and monitored weekly, using CBC counts and a polymerase chain reaction (PCR) designed to detect both genetic variants of H felis. Beginning 26 days after inoculation, 11 cats were administered azithromycin (15 mg/kg of body weight, PO, q 12 h, for 7 days). RESULTS: Inoculation resulted in coinfection with Hflg and Hfsm, and both variants were detected by PCR. Clinical abnormalities and anemia were most severe in Hflg- and dual-infected cats. Results of PCR and CBC were positive for H felis in 112/112 (100%) and 42/112 (37.5%), respectively, samples collected after inoculation. Administration of azithromycin had little effect on clinical variables, including anemia. All cats, regardless of treatment with azithromycin, had positive results for the PCR at the end of the study period. CONCLUSIONS AND CLINICAL RELEVANCE: In these cats, Hflg was more pathogenic than Hfsm, and coinfection with both variants was detected. Results of the PCR were superior to results of CBC for detecting infection with H felis. Azithromycin administered at the dose and duration reported here was not efficacious for the treatment of cats with hemobartonellosis.     

Cold agglutinins in cats with haemobartonellosis

Coombs-positive anemia developed in cats inoculated with Haemobartonella felis. Cold agglutinins were detected in serum during the acute stage of the disease when anemia was present. The cold agglutinating activity was associated with IgM, was demonstrated at 4 C, and was abolished by treatment of sera with 2-mercaptoethanol. At 4 C, the sera from infected cats agglutinated or lysed parasitized autologous erythrocytes or normal erythrocytes pretreated with neuraminidase. These data indicate that cold agglutinins are associated with haemobartonellosis and suggest that immunologic responses to erythrocytic antigens have a role in the anemia.     

Helicobacter spp. infection in cats: evaluation of the humoral immune response and prevalence of gastric Helicobacter spp

The principal aims of this study were to evaluate the humoral immune response (IgG) of cats with gastric Helicobacter spp. infection, and to determine the prevalence of different types of Helicobacter spp. in the stomachs of cats. The Helicobacter infection status of 45 cats (12 healthy spay/neuter cats, 9 sick cats, 24 colony cats) was determined by evaluating endoscopic gastric biopsies for urease activity, presence of Helicobacter-like organisms (HLO) on histopathology, and genus and species-specific PCR. Serum samples were evaluated with a kinetic enzyme linked immunosorbent assay (ELISA) utilizing the high molecular cell-associated protein (HM-CAP) fraction of H. felis ATCC 49179.Seventeen of 45 cats were infected with Helicobacter spp.: "H. heilmannii" 9/17, H. felis 4/17, mixed "H. heilmannii" and H. felis 3/17, unclassified-Helicobacter spp. 7/17. H. pylori was not detected in any cat. Kinetic ELISA results were significantly higher for infected cats, than for uninfected cats. Cats infected with different Helicobacter spp. showed similar distribution of OD/min values. There were no effects of age or clinical signs on the results of kinetic ELISA. No correlation between colonization density and seroconversion was observed. There were statistically significant, but weak correlations between the degree of seroconversion and the degree of inflammation, and the number of lymphoid follicles. Infected cats had more severe inflammation in the pylorus and fundus than uninfected cats. Infected sick cats had a higher degree of pyloric, but not fundic inflammation, than healthy infected cats and uninfected sick cats.The results indicate that naturally acquired infection with gastric Helicobacter spp. is associated with seroconversion (IgG) in cats. The similar ELISA values in cats infected with a variety of Helicobacter spp. suggests substantial antigenic homology between different Helicobacter spp. The higher degree of inflammation in infected than uninfected cats, supports a role for Helicobacter as a cause of gastritis in cats.     

Cytauxzoon felis infection in cats in the mid-Atlantic states: 34 cases (1998-2004)

OBJECTIVE: To describe the demographic and clinical characteristics of feline cytauxzoonosis in the mid-Atlantic states and compare the Cytauxzoon felis 18S rRNA gene sequences from affected cats with sequences reported from affected cats in other regions. DESIGN: Retrospective case series. ANIMALS: 34 cats with C. felis infection. PROCEDURE: Medical records of cats in which C. felis infection was diagnosed from May 1998 through June 2004 were reviewed; data collected included signalment, month of diagnosis, geographic location, clinicopathologic abnormalities, medical treatments, outcome, and necropsy findings when applicable. Cytauxzoon felis DNA was amplified, cloned, and sequenced from 4 of these cats and compared with previously reported C. felis DNA sequences. RESULTS: Of 34 C. felis-infected cats, 28 resided in North Carolina, 3 resided in South Carolina, and 3 resided in Virginia; in 32 cats, a diagnosis of C. felis infection was made in April through September. Pancytopenia and icterus were the most common clinicopathologic abnormalities. Thirty-two cats either died or were euthanatized, and 2 cats survived. At 5 veterinary hospitals, multiple cases were identified, and 4 multicat households had > 1 cat infected with C. felis. The 18S rRNA gene sequences characterized in organisms obtained from 4 cats were nearly identical to C. felis DNA sequences reported from other US regions. CONCLUSIONS AND CLINICAL RELEVANCE: Data indicate that veterinarians in the mid-Atlantic region of the United States should consider C. felis infection in cats that become ill with fever, icterus, and pancytopenia or bicytopenia, especially in the spring and summer months.     

Efficacy of pradofloxacin in cats with feline upper respiratory tract disease due to Chlamydophila felis or Mycoplasma infections

BACKGROUND: Upper respiratory tract disease (URTD) of cats is caused by a number of pathogens, including Chlamydophila felis and Mycoplasma spp. For effective treatment of both infections, doxycycline and enrofloxacin are recommended, but adverse effects limit their use in cats. HYPOTHESIS: That the fluoroquinolone pradofloxacin is effective against C. felis and Mycoplasma infection in cats with URTD or conjunctivitis. ANIMALS: Thirty-nine cats with signs of URTD or conjunctivitis. METHODS: Placebo-controlled, double-blind clinical trial. Cats were randomly entered into 1 of 2 treatment groups: treated PO with either 5 mg/kg pradofloxacin q24h or 5 mg/kg doxycycline q12h for 42 consecutive days. Changes in health status and clinical scores were evaluated. The presence of C. felis and Mycoplasma spp. was determined by quantitative polymerase chain reaction (PCR) and nested PCR of conjunctival swabs, respectively. RESULTS: At the beginning of the study, C. felis and Mycoplasma spp. were detected in 23 and 20 cats, respectively. Cats of both groups responded rapidly with a marked improvement in clinical signs within the 1st week. During treatment with either drug, C. felis DNA copy number declined quickly. Complete elimination of Mycoplasma spp. was achieved in both groups; however, whereas all cats receiving doxycycline eliminated C. felis, 4 cats treated with pradofloxacin remained PCR-positive. CONCLUSION AND CLINICAL IMPORTANCE: This study demonstrates that both pradofloxacin and doxycycline have good efficacy against C. felis and Mycoplasma spp., resulting in a marked improvement of clinical signs. However, C. felis DNA remained in some cats after treatment with pradofloxacin, suggesting that infection might not have been eliminated.     

Retrospective study of 46 cases of feline haemobartonellosis in Israel and their relationships with FeLV and FIV infections

Forty-six cats with clinical haemobartonellosis were studied; 75 per cent of the cats of known age were two-and-a-half years old or younger, 50 per cent were intact males and 19.5 per cent were castrated males. The predominant signs of the disease were tachypnoea, lethargy, depression, anorexia, infestation with fleas, pale mucous membranes, icterus, emaciation, dehydration, splenomegaly, anaemia, leucocytosis, increased activities of alanine aminotransferase and aspartate aminotransferase, and azotaemia. Thirty-eight per cent of the cats that were tested for feline leukaemia virus (FeLV) antigen were positive, and 22 per cent of those tested for feline immunodeficiency virus (FIV) antibodies were positive. The prevalence of both FeLV and FIV was much higher than in the general Israeli cat population. The cats infected with both Haemobartonella felis and FeLV had a significantly lower body temperature, were more anaemic and the mean cell volume of their erythrocytes was greater than in the cats with haemobartonellosis alone.     

Anemia in cats with hemotropic mycoplasma infection: Retrospective evaluation of 23 cases (1996–2005)

This study summarizes the diagnostic findings from all anemic cats diagnosed with hemotropic mycoplasma (HM) infections at the Western College of Veterinary Medicine — Veterinary Teaching Hospital between 1996 and 2005. The objectives were to determine the frequency of HM-induced anemia among all cats presented with anemia during this period, the clinical findings and risk factors associated with clinical HM infection, and factors affecting or predicting survival. Medical records were examined from 23 cats with HM-induced anemia from the total of 170 cats diagnosed with anemia during this period. The frequency of HM-induced anemia was 14% (23/170) among all anemic cats. Cats with HM-induced anemia were less likely to be purebred (P = 0.04) than other cats with anemia. Of the cats with HM-induced anemia, those with positive retroviral status (P = 0.01), concurrent illness (P < 0.01), or lack of erythroid regeneration (P = 0.01) were most likely to die. The 1-year survival of HM-infected cats was 65% (13/20).     

Temporal occurrence and environmental risk factors associated with cytauxzoonosis in domestic cats

Cytauxzoon felis is a tick-transmitted protozoan parasite of domestic and wild felids in the south-central and southeastern United States. Infection of domestic cats (Felis domesticus) with C. felis is typically acute and characterized by fever, anorexia, listlessness, anemia, icterus and usually death within 19-21 days. To determine the temporal occurrence and environmental risk factors associated with infection of C. felis in domestic cats from Oklahoma, information in the electronic medical records from the Oklahoma Animal Disease Diagnostic Laboratory (OADDL) and Boren Veterinary Medical Teaching Hospital (BVMTH) was retrospectively searched. A total of 232 cytauxzoonosis cases from 1995 to 2006 from OADDL (n=180) and 1998 to 2006 from BVMTH (n=52) were combined and analyzed. The number of cytauxzoonosis cases remained relatively consistent from year to year. Diagnosis of C. felis infection in domestic cats followed a bimodal pattern with a peak in the number of cases in April, May, and June followed by a second smaller peak in August and September. The majority (n=72; 31.0%) of cytauxzoonosis cases were diagnosed in May. No cases of C. felis infection were diagnosed in December and only a few (n=10; 4.3%) cases were observed from November through March during the 12-year period. In cases for which the client's address was available, geographic coordinates were assigned and landscape characteristics were quantified within a 100-m radius of each cytauxzoonosis case location. Of cytauxzoonosis cases (n=41) with a known client address, a majority (n=28; 68.3%) occurred in low density residential areas and more cases (n=8; 19.5%) were found in urban edge habitat than expected at random. Locations of diagnosed cytauxzoonosis cases were significantly associated with more wooded (31.8+/-4.03%) cover and closer (55.5+/-18.45m) proximity to natural or unmanaged areas than randomly selected control sites. Practicing and diagnostic veterinarians can expect to see a distinct temporal pattern in cases of cytauxzoonosis and more cases can be expected in domestic cats living in close proximity to environments that support tick vectors and bobcats.     

Pharmacokinetics of enrofloxacin and its efficacy in comparison with doxycycline in the treatment of Chlamydophila felis infection in cats with conjunctivitis

The concentrations of enrofloxacin were measured in the tears, saliva and serum of 14 cats with signs of upper respiratory tract infection and eight with no signs, after daily doses of 5 mg/kg. Enrofloxacin concentrations above the minimum inhibitory concentration of Chlamydophila felis were found in the saliva and tears of the cats with and without signs of upper respiratory tract infection. In a prospective randomised clinical trial, the efficacy of enrofloxacin against C. felis infection in cats with conjunctivitis was compared with the efficacy of doxycycline. Twenty-five cats were randomly assigned to treatment with either enrofloxacin or doxycycline for 14 days; 15 of the cats tested positive for C. felis by an immunofluorescent antibody test on conjunctival swabs. The two treatment groups showed equal improvements in the clinical signs of conjunctivitis and C. felis infection status; in each group three cats were still C. felis antigen-positive after the 14-day course of treatment, indicating a persistent infection. No side effects were observed in the cats treated with enrofloxacin.     

Haemobartonella felis infection in cats from the Glasgow area

A survey of 155 cats for Haemobartonella felis infection in the Glasgow area revealed a prevalence of 23.2 per cent. The infection occurred in all age groups and there was no significant difference between sex or breed type. Infection with H felis was more prevalent among cats with fleas and those with feline leukaemia virus infection than among the other cats in the sample. H felis organisms identified were mainly coccoid with diameters between 0.63 micron and 1.73 micron. Rod forms, found in two cats, had lengths ranging from 0.79 micron to 1.1 micron and diameters between 0.17 micron and 0.24 micron.     

Infections with helminths and/or protozoa in cats in animal shelters in the Netherlands

To determine the prevalence of infections with helminths and protozoa in cats in animal shelters, faecal samples from 305 cats from 22 animal shelters in the Netherlands were examined, using a centrifugation-sedimentation-flotation-technique. The association between potential risk factors and the occurrence of an infection was also tested. Infections with helminths and/or protozoa were found in 160 samples (52.5%). Toxocara cati was found in 86 cats (28.2%), Cystoisospora felis in 59 cats (19.3%), Cysto?sospora rivolta in 43 cats (14.1%), Capillaria spp. in 34 cats (11.2%), Ancylostoma tubaeforma in 9 cats (3.0%), Taenia taeniaeformis in 9 cats (3.0%), Aelurostrongylus abstrusus in 8 cats (2.6%), Giardia intestinalis in 3 cats (1.0%), Dipylidium caninum in 2 cats (0.7%) and Toxoplasma gondii in 1 cat (0.3%). The highest prevalence was seen in kittens and stray cats. The main preventive factor against infection was a short stay in a shelter.     

Prevalences of various hemoplasma species among cats in the United States with possible hemoplasmosis

OBJECTIVE: To determine prevalences of various hemoplasma species among cats in the United States with possible hemoplasmosis and identify risk factors for and clinicopathologic abnormalities associated with infection with each species. DESIGN: Cross-sectional study. Animals-310 cats with cytologic evidence of hemoplasmosis (n = 9) or acute or regenerative anemia (309). PROCEDURES: Blood samples were tested by means of a broad-spectrum conventional PCR assay for hemoplasma DNA and by means of 3 separate species-specific real-time PCR assays for DNA from "Candidatus Mycoplasma haemominutum" (Mhm), Mycoplasma haemofelis (Mhf), and "Candidatus Mycoplasma turicensis" (Mtc). RESULTS: Overall prevalences of Mhm, Mhf, and Mtc infection were 23.2% (72/310), 4.8% (15/310), and 6.5% (20/310), respectively. Mixed infections were detected in 20 (6.5%) cats. Cats infected with hemoplasmas were more likely to be male than were uninfected cats. Infection with FeLV or FIV was significantly associated with infection with Mhf. Compared with uninfected cats, cats infected with Mhf had higher reticulocyte counts, nucleated RBC counts, and mean corpuscular volume; cats infected with Mhm had higher mean corpuscular volume; and cats infected with Mtc had higher monocyte counts. CONCLUSIONS AND CLINICAL RELEVANCE: Results supported the suggestion that these 3 hemoplasma species commonly occur among cats in the United States and that pathogenicity of the 3 species varies.     

Prevalence of Chlamydophila felis and feline herpesvirus 1 in cats with conjunctivitis in northern Italy

The prevalence of Chlamydophila felis and feline herpesvirus 1 (FHV-1) infection in cats with conjunctivitis in northern Italy was investigated by conventional polymerase chain reaction (PCR) testing. In cats with conjunctivitis, C felis and FHV-1 were detected in 14 of 70 (20%) and in 23 of 70 (33%) animals, respectively. None of the 35 control cats were positive for C felis, whereas 7 (20%) of these cats were positive for FHV-1. Mixed infections were present in 5 of 70 cats (7%). Cats positive for C felis were significantly younger than control animals (P = .02), whereas no significant age differences were observed between FHV-1-positive cats and control cats (P = .41) or between FHV-1-positive animals and C felis-positive animals (P = .16). Cats sampled during acute-phase conjunctivitis were also investigated for the presence of C felis by conjunctival scrapings. In this acute phase, substantial agreement was found when comparing the results of the 2 methods (K = .80). The association between PCR results and conjunctivitis was evaluated for the 2 pathogens. The presence of C felis was significantly associated with conjunctivitis (P = .004), whereas the detection of FHV-1 did not significantly correlate with the clinical sign (P = .25), suggesting that, by itself. PCR is not suitable for the diagnosis of FHV-1-related conjunctivitis.     

The detection of Cytauxzoon felis in apparently healthy free-roaming cats in the USA

Cytauxzoon felis typically causes fatal disease in domestic cats. Survival after infection and persistent parasitemia without clinical illness has been documented in a few cases. To our knowledge there are no prevalence studies of C. felis in domestic cats. The purpose of this study was to estimate the prevalence of C. felis infected cats that were presented to trap-neuter-return programs in Florida, North Carolina and Tennessee. Cats that were presented to trap-neuter-return programs were tested using a C. felis-specific PCR assay. A total of 961 domestic cats were tested (494 from Florida; 392 from North Carolina; 75 from Tennessee). Prevalence of C. felis infection in this population was 0.3%. Two cats from Florida and one cat from Tennessee tested positive for the presence of C. felis DNA. These amplicons were sequenced and confirmed to be C. felis. The cat from Tennessee was alive without evidence of illness 2 months post-surgery. The other two cats were alive 24 h post-surgery, but were then lost to follow-up. This is the first report documenting C. felis infections in free-roaming cats. Despite the low prevalence rate, the presence of apparently healthy infected free-roaming cats suggests that they may have the capacity to serve as an additional reservoir host for C. felis. Further investigations should evaluate the potential vector competence of domestic cats as well as the role of chronically infected cats in areas in which cytauxzoonosis appears hyperendemic.