The immunologic response of dogs to Bartonella vinsonii subspecies berkhoffii antigens: as assessed by Western immunoblot analysis.

Bartonella vinsonii subspecies berkhoffii is a recently recognized zoonotic pathogen that causes endocarditis, granulomatous rhinitis, and granulomatous lymphadenitis in dogs. Isolation of B. vinsonii (berkhoffii) from blood or tissue samples is frequently unsuccessful; therefore, diagnosis is primarily dependent on serologic or molecular testing modalities. Because previous canine serologic studies have used an indirect immunofluorescence assay (IFA), without Western immunoblot (WI) confirmation, the overall objective of this study was to examine the diagnostic use of WI for confirmation of B. vinsonii (berkhoffii) infection in dogs. To confirm that agar-grown and cell culture-grown organisms yielded similar patterns of WI antigenic protein recognition, the 2 preparations were compared using IFA-reactive sera obtained from dogs experimentally infected with B. vinsonii (berkhoffii). Temporal changes in the pattern of antigenic protein recognition were characterized using sera obtained from dogs at various time points after experimental B. vinsonii (berkhoffii) infection. The specificity of B. vinsonii (berkhoffii) WI was examined by testing canine sera that were reactive to B. henselae, B. clarridgeiae, Ehrlichia canis, Rickettsia rickettsii, Babesia canis, Anaplasma phagocytophilum (previously E. equi), or Brucella canis antigens. Clinical accessions including serum samples obtained from B. vinsonii (berkhoffii) culture-positive dogs and B. vinsonii (berkhoffii) culture-negative dogs that were IFA seroreactive to B. vinsonii (berkhoffii) antigens were examined by WI. The results of this study indicate that WI using agar-grown or cell culture-grown B. vinsonii (berkhoffii) antigens produce identical patterns of antigenic protein recognition. After experimental infection, there is a progressive increase in the number of antigenic proteins that are recognized by WI, with the 33-kD antigen representing the first and the most persistent antigen recognized by B. vinsonii (berkhoffii)-infected dogs. Regarding specificity, sera from dogs that were reactive to various heterologous antigens did not recognize B. vinsonii (berkhoffii) antigens by IFA or WI, and sera from dogs experimentally infected with B. henselae did not recognize B. vinsonii (berkhoffii) antigens by WI. Regarding clinical accessions, there was good agreement between B. vinsonii (berkhoffii) IFA test results and WI analysis. Western immunoblot analysis can be used to detect or confirm exposure to B. vinsonii (berkhoffii) in dogs.     

Bartonella henselae IgG antibodies are prevalent in dogs from southeastern USA

In contrast to the large body of literature regarding Bartonella henselae in humans and cats, there is little information about B. henselae as an infectious agent in dogs. Due to the paucity of information regarding the B. henselae serology in dogs, we performed a cross-sectional serosurvey using B. henselae antigen in order to compare the seroprevalence between sick and healthy dogs from the south-eastern USA. Ninety-nine sera were collected from clinically healthy dogs. Three hundred and one sera from sick dogs were submitted to North Carolina State University for serologic screening against a panel of arthropod-transmitted organisms. Serological tests were performed using B. henselae (Bh), Rickettsia rickettsii (Rr), Ehrlichia canis (Ec), Bartonella vinsonii subspecies berkhoffii (Bvb), Babesia canis (Bc) and Borrelia burgdorferi (Bb) antigens. Serum B. henselae IgG antibodies were detected in 10.1% of healthy dogs and in 27.2% of sick dogs. The difference in seroprevalence between the two groups was statistically significant. The majority of seroreactive dogs (80%) had low titers of 1:64 or 1:128. In healthy dogs, seroprevalence for Rr was 14.1% and for Bvb was 1%. In sick dogs, Rr seroprevalence was 29.7%, Ec 6.5%, Bvb 4.7%, Bb 1.7% and Bc was 0.85%. Of the sick dogs that were seroreactive to B. henselae antigens, 40.6% were also seroreactive to Rr, 15.0% reactive to Bvb antigens, 14.8% reactive to Ec antigens, 1.8% reactive to Bc antigens and 1.75% reactive to Bb antigens. Sera from dogs experimentally infected with B. vinsonii subsp. berkhoffii, E. canis or R. rickettsii did not cross react with B. henselae antigens, by IFA testing. This study indicates that B. henselae IgG antibodies are prevalent in healthy and sick dogs living in the south-eastern USA. Nevertheless, further studies are needed to evaluate the epidemiological, clinical and zoonotic relevance of B. henselae infection in dogs.     

Chronic canine ehrlichiosis (Ehrlichia canis): a retrospective study of 19 natural cases

Nineteen dogs from Greece with chronic ehrlichiosis were studied. The dogs exhibited bicytopenia or pancytopenia, bone marrow hypoplasia, seroreactivity to Ehrlichia canis (E. canis) antigens, and had no history of drug or radiation exposure. Anorexia, depression, severe bleeding tendencies, hypoalbuminemia, and increased serum alanine aminotransferase activity were also hallmarks of the disease. All these animals eventually died, irrespective of the treatment applied. Some dogs were also serologically positive for Rickettsia conorii, Leishmania infantum (L. infantum), and Bartonella vinsonii subspp. berkhoffii. Polymerase chain reaction testing of bone marrow samples revealed E. canis, Anaplasma phagocytophilia, Anaplasma platys, and L. infantum in some dogs. Concurrent infections did not appear to substantially influence the clinical course and final outcome of the chronic canine ehrlichiosis.     

Serologic and molecular evidence of coinfection with multiple vector-borne pathogens in dogs from Thailand

Forty-nine dogs from Thailand were evaluated for serologic evidence of exposure or polymerase chain reaction (PCR) evidence of infection with vectorborne pathogens, including Ehrlichia sp. (Ehrlichia canis, Ehrlichia chaffeensis, Ehrlichia equi, and Ehrlichia risticii), Bartonella vinsonii subsp. berkhoffi (Bvb), spotted fever group (SFG) rickettsiae (Rickettsia rickettsii), Typhus group (TG) rickettsiae (Rickettsia canada, Rickettsia prowazekii, and Rickettsia typhi), and Babesia sp. (Babesia canis and Babesia gibsonii). All study dogs had at least 1 of 3 entry criteria: fever, anemia, or thrombocytopenia. By immunofluorescence antibody (IFA) testing, seroreactivity was most prevalent to E chaffeensis (74%) and E canis (71%) antigens, followed by E equi (58%), Bvb (38%), E risticii (38%), R prowazekii (24%), B canis (20%), R rickettsii (12%), R canada (4%), and B gibsonii (4%) antigens. There was 100% concordance between E canis IFA and Western blot immunoassay (WI) for 35 of 35 samples; 2 samples were IFA and WI reactive only to E equi antigens. By PCR amplification, 10 dogs were found to be infected with E canis, 5 with Ehrlichia platys, and 3 with B canis. Sequencing of PCR products was undertaken to compare Ehrlichia strains from Thailand to strains originating from the United States. Partial DNA sequence analysis confirmed infection with E canis and E platys, with identical 16S rRNA sequence alignment to E canis (U26740) and to E platys (M83801), as reported in GenBank. Partial E canis P28.1 and P28.2 amino acid sequences from Thai dogs were divergent from analogous sequences derived from North American E canis (AF082744) strains, suggesting that the Thai dogs were infected with a geographically distinct strain of E canis compared to North American strains. The results of this study indicate that dogs in Thailand have substantial exposure to vectorborne diseases and that coinfection with these pathogens may be common.     

Perinuclear antineutrophil cytoplasmic autoantibodies in dogs infected with various vector-borne pathogens and in dogs with immune-mediated hemolytic anemia

Objective-To determine the prevalence of perinuclear antineutrophil cytoplasmic autoantibodies (pANCA) in dogs with confirmed or suspected immune-mediated hemolytic anemia (IMHA) or dogs infected with various vector-borne pathogens, including Rickettsia rickettsii, Bartonella henselae, Bartonella vinsonii subsp berkhoffii, Ehrlichia canis, Borrelia burgdorferi, and Leishmania infantum. Animals-55 dogs with confirmed or suspected IMHA, 140 dogs seroreactive for vector-borne pathogens, and 62 healthy dogs and dogs seronegative for vector-borne pathogens. Procedures-Samples were allocated to subgroups on the basis of the health status of the dogs and the degree of seroreactivity against various vector-borne pathogens. Serum samples were tested retrospectively via indirect immunofluorescence assay to determine pANCA status. Results-26 of 55 (47%) dogs with confirmed or suspected IMHA and 67 of 140 (48%) dogs seroreactive for vector-borne pathogens had positive results when tested for pANCA. Serum samples with the highest antibody concentrations against L infantum antigen had the highest proportion (28/43 [65%]) that were positive for pANCA. One of 20 (5%) dogs seronegative for tick-borne pathogens and 8 of 22 (36%) dogs seronegative for L infantum had positive results for pANCA. One of 20 (5%) healthy dogs had serum antibodies against pANCA. Conclusions and Clinical Relevance-pANCA were detected in a high percentage of dogs with IMHA and vector-borne infectious diseases. Therefore, pANCA may be a relatively nonspecific marker for dogs with inflammatory bowel disease, although they could represent a biomarker for immune-mediated diseases and infections.     

Assessing the association between the geographic distribution of deer ticks and seropositivity rates to various tick-transmitted disease organisms in dogs

OBJECTIVE: To determine whether the geographic distribution of deer ticks (Ixodes scapularis) was associated with the distribution of dogs seropositive for various tick-transmitted disease organisms (ie, Borrelia burgdorferi, Rickettsia rickettsii, the human granulocytic ehrlichiosis [HGE] agent, Ehrlichia canis, and Bartonella vinsonii subsp berkhoffii). DESIGN: Serologic survey. SAMPLE POPULATION: Serum samples from 277 dogs in animal shelters and veterinary hospitals in Rhode Island. RESULTS: Overall, 143 (52%) dogs were seropositive for B burgdorferi, 59 (21.3%) were seropositive for R rickettsii, 40 (14.4%) were seropositive for the HGE agent, 8 (2.9%) were seropositive for E canis, and 6 (2.2%) were seropositive for B vinsonii. Regression analysis indicated that the natural logarithm of nymphal deer tick abundance was correlated with rate of seropositivity to the HGE agent and to B burgdorferi but not to rate of seropositivity to R rickettsii, E canis, or B vinsonii. Percentages of samples seropositive for B burgdorferi, R rickettsii, the HGE agent, and E canis were significantly higher for samples from the southwestern part of the state where ticks in general and deer ticks in particular are abundant than for samples from the northern and eastern portions of the state, where ticks are relatively rare. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that all 5 disease agents are in Rhode Island and pose a risk to dogs and humans. Knowledge concerning tick distributions may be useful in predicting the pattern of disease associated with particular tick species and may aid diagnostic, prevention, and control efforts.     

Cyclic CD8+ lymphopenia in dogs experimentally infected with Bartonella vinsonii subsp. berkhoffii

Until recently, it was presumed that Bartonella vinsonii only infected voles, a species of North American rodents. In April of 1993, however, our laboratory isolated a novel subspecies of B. vinsonii (B. vinsonii subsp. berkhoffii) from the blood of a dog diagnosed with vegetative valvular endocarditis. Subsequently, based on a seroepidemiologic survey of dogs from North Carolina and Virginia presenting for a variety of medical problems, we found evidence supporting a potentially important association between B. vinsonii and Ehrlichia canis co-infection in dogs. In the following study, eight dogs were infected with B. vinsonii: four specific pathogen free dogs and four dogs that had previously been infected with E. canis. Flow cytometric analysis of peripheral blood lymphocytes revealed a cyclic elevation of the CD4/CD8 T-cell ratio that correlated with cyclic CD8+ lymphopenia in all dogs infected with B. vinsonii, regardless of prior exposure to E. canis.     

Seroprevalence of Ehrlichia canis, Ehrlichia equi, and Ehrlichia risticii in sick dogs from North Carolina and Virginia

Ehrlichia canis, E. equi, and E. risticii seroprevalence was determined by microimmunofluorescent antibody testing (IFA) in a sequential population of 1,845 sick dogs admitted during a 1-year period to the North Carolina State University Veterinary Teaching Hospital. A seroreactor was defined by a reciprocal IFA titer of > or =80 to E. canis, E. equi, or E. risticii antigens. Of the 48 IFA seroreactors, 44 dogs were seroreactive to E. canis, 21 to E. equi, and 0 to E. risticii. Seventeen dogs reacted to both E. canis and E. equi antigens. There was concordance of E. canis IFA and western immunoblot (WI) test results for 36/44 dogs. Because of cross-reactivity of E. canis sera with E. equi antigens, WI was of less utility to confirm E. equi exposure. After elimination of E. canis seroreactors, there was concordance of 2/4 E. equi IFA and WI test results. Based upon a retrospective review of medical records, ehrlichiosis was diagnosed in 10/48 (21%) IFA seroreactive dogs, 9 of which were confirmed positive by WI. Of the remaining 38 IFA seroreactors, 29 also were confirmed by E. canis or E. equi WI. These results indicate that (1) ehrlichiosis was not diagnosed in the majority of serologically confirmed cases, (2) based upon E. canis and E. equi WI analysis, IFA testing was not specific (21% false positive), (3) E. canis sera cross-react with E. equi antigens, and (4) serologic evidence of E. risticii infection was lacking in the dog population studied.     

A serological study of exposure to arthropod-borne pathogens in dogs from northeastern Spain

There is limited information regarding the prevalence of many vector borne pathogens in Europe and especially in Spanish dogs. We investigated 206 sick and 260 clinically healthy dogs from three different regions in northeastern Spain for antibodies to Rickettsia conorii (Rc), Ehrlichia canis (Ec), Anaplasma phagocytophilum (Ap), Bartonella henselae (Bh), Bartonella vinsonii subsp. berkhoffii (Bvb), Leishmania infantum (Li) and Borrelia burgdorferi (Bb) and for antigen of Dirofilaria immitis (Di). Total prevalences were the following: Rc (56.4%), Li (30%), Ec (16.7%), Bh (16.8%), Ap (11.5%), Bvb (1.07%), Di (0.6%) and Bb (0.6%). Seroprevalences for Rc, Ec, Ap, Bh, and Bvb and Bb and Di antigens were similar among the three different study sites. The Ec seroprevalence, as determined by Snap 3DX, was statistically lower in dogs from Mallorca (0%) than Tarragona (16%) and Barcelona (5%) (P < 0.0001). Detection of Rc antibodies was associated with seroreactivity to Ec and Ap antigens (P = 0.018 and P = 0.002, respectively). IFA Ec antibodies were associated with Ap seroreactivity (P < 0.0001). There was no association between the clinical status, sex, time of the year when samples were collected, life-style or exposure to fleas or ticks and a positive test result for Ec, Bh, Bvb, or Bb antibodies or Di antigens. Li seroreactivity was associated with illness and living outdoors (P < 0.0001, P = 0.029; respectively), Rc seroreactivity with the male gender (P = 0.028) and Ap seroreactivity with living outdoors (P = 0.045). This study indicates that exposure to Rc, Li, Ec or related Ehrlichia spp., Bh and Ap or a related spp., is common whereas Di, Bb and Bvb is uncommon among dogs from the Mediterranean basin. We also provide serological data that suggests the existence of a novel Ehrlichia species on Mallorca island.     

A serological survey of Ehrlichia canis, Ehrlichia equi, Rickettsia rickettsii, and Borrelia burgdorferi in dogs in Oklahoma

Serum samples from 259 dogs were tested for antibodies to Ehrlichia canis, Ehrlichia equi, Rickettsia rickettsii, and Borrelia burgdorferi using the indirect fluorescent antibody test. The sera were obtained from submissions to the Oklahoma Animal Disease Diagnostic Laboratory during a 14-month period from June 1986 through July 1987. The rate for positive antibody titers to E. canis was 53%, to E. equi was 33%, to R. rickettsii was 38%, and to B. burgdorferi was 18%. Higher percentages of sera serologically positive to E. canis were found in the spring through the fall months, but there were no seasonal variations for E. equi, R. rickettsii, and B. burgdorferi. There was no consistent pattern of titers to the 4 antigens when age-groups of the dogs were compared. Forty-four different breeds were tested.     

Prevalence of Ehrlichia canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, Bartonella vinsonii berkhoffii, and Rickettsia spp. in dogs from Grenada

To identify the tick-borne pathogens in dogs from Grenada, we conducted a serologic survey for Ehrlichia canis in 2004 (104 dogs) and a comprehensive serologic and molecular survey for a variety of tick-borne pathogens in 2006 (73 dogs). In 2004 and 2006, 44 and 32 dogs (42.3% and 43.8%) were seropositive for E. canis, respectively. In 2006, several tick-borne pathogens were identified by serology and PCR. DNA of E. canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, and Bartonella sp. were identified in 18 (24.7%), 14 (19.2%), 5 (7%), 5 (7%), and 1 (1.4%) dogs, respectively. Six (8.2%) dogs were seropositive for Bartonella vinsonii subsp. berkhoffii. All dogs were seronegative and PCR-negative for Rickettsia spp. Coinfection with two or three pathogens was observed in eight dogs. Partial 16S rRNA E. canis and A. platys sequences were identical to sequences in GenBank. Partial 18S rRNA gene sequences from the Grenadian H. canis were identical to each other and had one possible mismatch (ambiguous base) from H. canis detected from Spain and Brazil. Grenadian B. c. vogeli sequences were identical to B. c. vogeli from Brazil and Japan. All of the detected pathogens are transmitted, or suspected to be transmitted, by Rhipicephalus sanguineus. Results of this study indicate that dogs from Grenada are infected with multiple tick-borne pathogens; therefore, tick-borne diseases should be included as differentials for dogs exhibiting thrombocytopenia, leukopenia, fever, or lethargy. One pathogen, E. canis, is also of potential public health significance.     

Clinicopathological abnormalities and treatment response in 24 dogs seroreactive to Bartonella vinsonii (berkhoffii) antigens

Bartonella vinsonii (B. vinsonii) subspecies berkhoffii is a recently recognized cause of endocarditis, myocarditis, and granulomatous disease in dogs. In an effort to elucidate other potential disease manifestations, the case records of 24 dogs that were seroreactive to B. vinsonii (berkhoffii) antigens were studied retrospectively. Diagnoses included immune-mediated hemolytic anemia, neutrophilic or granulomatous meningoencephalitis, neutrophilic polyarthritis, cutaneous vasculitis, and uveitis. Repeated B. vinsonii (berkhoffii) antibody titers became negative after treatment. This study indicates that a diverse spectrum of disease manifestations and clinicopathological abnormalities can be detected in dogs that are seroreactive to B. vinsonii (berkhoffii) antigens.     

Seroprevalence of antibodies against Bartonella species and evaluation of risk factors and clinical signs associated with seropositivity in dogs

OBJECTIVE: To determine the seroprevalence of antibodies against Bartonella spp in a population of sick dogs from northern California and identify potential risk factors and clinical signs associated with seropositivity. SAMPLE POPULATION: Sera from 3,417 dogs. PROCEDURE: Via an ELISA, sera were analyzed for antibodies against Bartonella vinsonii subsp berkhoffii, Bartonella clarridgeiae, and Bartonella henselae; test results were used to classify dogs as seropositive (mean optical density value > or = 0.350 for B henselae or > or = 0.300 for B clarridgeiae or B vinsonii subsp berkhoffi) or seronegative. Overall, 305 dogs (102 seropositive and 203 seronegative dogs) were included in a matched case-control study. RESULTS: 102 of 3,417 (2.99%) dogs were seropositive for > or = 1 species of Bartonella. Of these, 36 (35.3%) had antibodies against B henselae only, 34 (33.3%) had antibodies against B clarridgeiae only, 2 (2.0%) had antibodies against B vinsonii subsp berkhoffii only, and 30 (29.4%) had antibodies against a combination of those antigens. Compared with seronegative dogs, seropositive dogs were more likely to be herding dogs and to be female, whereas toy dogs were less likely to be seropositive. Seropositive dogs were also more likely to be lame or have arthritis-related lameness, nasal discharge or epistaxis, or splenomegaly. CONCLUSIONS AND CLINICAL RELEVANCE: Only a small percentage of dogs from which serum samples were obtained had antibodies against Bartonella spp. Breed appeared to be an important risk factor for seropositivity. Bartonella infection should be considered in dogs with clinical signs of lameness, arthritis-related lameness, nasal discharge or epistaxis, or splenomegaly.     

Antibodies reactive with Bartonella henselae and Ehrlichia canis in dogs from the communal lands of Zimbabwe

The prevalences of antibodies against Bartonella henselae and Ehrlichia canis were determined in sera from 228 dogs in 5 communal lands of Zimbabwe, areas where traditional subsistence agro-pastoralism is practised. The sera were collected from apparently healthy dogs during routine rabies vaccination programmes and tested with indirect fluorescent antibody assays using B. henselae (Houston-I) and E. canis (Oklahoma) as antigens. We found reactive antibodies (> or =1:80) against B. henselae in 14% of the dogs tested. Seropositive animals were found in Bikita (41%; 17/42), Omay (13%; 6/48), Chinamora (5%; 2/38) and Matusadona (15%; 7/48). No seropositive dogs were found in Chiredzi (0%; 0/52). Antibodies reactive with E. canis (> or =1:80) were found in 34% of the dogs tested, from Bikita (88%; 37/42), Chiredzi (31%; 16/52), Omay (17%; 8/48), Chinamora (26%; 10/38) and Matusadona (15%; 7/48). Our survey shows dogs in the communal lands of Zimbabwe are frequently exposed to E. canis and B. henselae or closely related species. Further studies are indicated to determine the pathogenicity of the organisms infecting these dogs and their clinical significance.     

Invasion of canine erythrocytes by Bartonella vinsonii subsp. berkhoffii

Bartonella vinsonii subsp. berkhoffii is a recognized cause of endocarditis in dogs and human patients and has been associated with cardiac arrhythmias, myocarditis, granulomatous lymphadenitis, polyarthritis, and granulomatous rhinitis in dogs. Little is known regarding the mode of transmission or cellular localization of this bacteria following infection of a canine host. The aim of the current study was to determine whether erythrocytes may serve as a site of infection by B. vinsonii subsp. berkhoffii. In the study, we successfully demonstrate the invasion of canine erythrocytes by a B. vinsonii subsp. berkhoffii genotype III strain using an in vitro model system. Dog erythrocytes were incubated with B. vinsonii subsp. berkhoffii after which tubes were treated with gentamicin at 12, 24, and 48 h post-inoculation. After gentamicin elimination of extracellular bacteria, there was a gradual increase in intra-erythrocytic bacteria, as assessed by colony forming units per ml, at each collection time point. The largest recovery of intracellular bacteria occurred at 48 h post-infection. These results suggest that canine erythrocytes may serve in the maintenance of bacteremia due to B. vinsonii subsp. berkhoffii within an infected host.     

Canine bartonellosis: serological and molecular prevalence in Brazil and evidence of co-infection with Bartonella henselae and Bartonella vinsonii subsp. berkhoffii

The purpose of this study was to determine the serological and molecular prevalence of Bartonella spp. infection in a sick dog population from Brazil. At the S?o Paulo State University Veterinary Teaching Hospital in Botucatu, 198 consecutive dogs with clinicopathological abnormalities consistent with tick-borne infections were sampled. Antibodies to Bartonella henselae and Bartonella vinsonii subsp. berkhoffii were detected in 2.0% (4/197) and 1.5% (3/197) of the dogs, respectively. Using 16S-23S rRNA intergenic transcribed spacer (ITS) primers, Bartonella DNA was amplified from only 1/198 blood samples. Bartonella seroreactive and/or PCR positive blood samples (n=8) were inoculated into a liquid pre-enrichment growth medium (BAPGM) and subsequently sub-inoculated onto BAPGM/blood-agar plates. PCR targeting the ITS region, pap31 and rpoB genes amplified B. henselae from the blood and/or isolates of the PCR positive dog (ITS: DQ346666; pap31 gene: DQ351240; rpoB: EF196806). B. henselae and B. vinsonii subsp. berkhoffii (pap31: DQ906160; rpoB: EF196805) co-infection was found in one of the B. vinsonii subsp. berkhoffii seroreactive dogs. We conclude that dogs in this study population were infrequently exposed to or infected with a Bartonella species. The B. henselae and B. vinsonii subsp. berkhoffii strains identified in this study are genetically similar to strains isolated from septicemic cats, dogs, coyotes and human beings from other parts of the world. To our knowledge, these isolates provide the first Brazilian DNA sequences from these Bartonella species and the first evidence of Bartonella co-infection in dogs.     

The low seroprevalence of tick-transmitted agents of disease in dogs from southern Ontario and Quebec

Infectious diseases caused by pathogens transmitted by ticks and other insect vectors are an important cause of morbidity and mortality in both dogs and humans throughout North America. The purpose of this study was to determine the seroprevalence of selected vector-transmitted pathogens in southern Ontario and Quebec. Samples submitted to the Vector Borne Disease Diagnostic Laboratory (VBDDL) at the North Carolina State University College of Veterinary Medicine were evaluated for antibodies to Ehrlichia canis, Anaplasma phagocytophilum, Babesia canis, Bartonella henselae, Borrelia burgdorferi, Bartonella vinsonii subspecies berkhoffii, and Rickettsia rickettsii. Information regarding breed and the city or province from which the sample originated was recorded; however, travel history was unknown for the majority of dogs. Overall seroprevalence to these tick-borne pathogens in southern Ontario and Quebec is low compared with most regions of the United States, suggesting that veterinarians in this region of Canada should pursue diagnostic evidence of infection in dogs with a travel history or prior residence in areas endemic for exposure to tick-borne infections.     

Seroepidemiology of Bartonella vinsonii subsp berkhoffii exposure among healthy dogs

OBJECTIVE: To determine seroprevalence of antibodies to Bartonella vinsonii subsp berkhoffii and risk factors for seropositivity among working dogs owned by the US government. DESIGN: Cross-sectional study. ANIMALS: 1,872 dogs. PROCEDURE: An ELISA was used to detect antibodies to B vinsonii subsp berkhoffii. RESULTS: Antibodies to B vinsonii subsp berkhoffii were detected in 162 dogs (8.7%; 95% confidence interval, 7.4 to 10.0%). Dogs living in the southeast, plains states, southwest, and south-central were significantly more likely to be seropositive than were dogs living in other regions of the United States. German Shepherd-type dogs were significantly less likely to be seropositive than were dogs of other breeds, and dogs entering training programs or that had been rejected from a training program were significantly more likely to be seropositive than were dogs used for narcotics detection and dogs trained to patrol or detect explosives. Dogs used by the border patrol or Federal Aviation Administration were more likely to be seropositive than were dogs used by the Department of Defense or customs service. Odds that dogs would be seropositive were significantly higher for dogs stationed in the southern United States, the northeastern United States, or a foreign country, compared with dogs stationed in all other regions of the United States. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, 8.7% of this diverse group of healthy dogs was found to be seropositive for antibodies to B vinsonii subsp berkhoffii, and seropositivity rates were associated with location, suggesting either that there are multiple vectors for the organism or that the major vector for the organism depends on geographic and environmental factors.     

Differential serological testing by simultaneous indirect immunofluorescent antibody test in canine leishmaniosis and ehrlichiosis

A mixed indirect fluorescence antibody test (IFAT), based on cultured promastigotes Leishmania infantum and formol-inactivated suspension of cells infected with the bacteria Ehrlichia canis, was applied to make a differential diagnosis between canine ehrlichiosis and leishmaniosis. A titre greater than 80 was considered positive for antibodies to E. canis and suggestive of antibodies to L. infantum. Positive sera were titrated subsequently by serial dilutions to confirm antibodies positive to Leishmania and establishing the antibody titre of both pathogens. Fluorescence was absent with negative control sera and background staining was minimal. No serological cross-reactions between positive sera for L. infantum or E. canis were detected. Results obtained by mixed IFAT did not differ when the same serum IFAT standard was compared. The test showed equivalent sensitivity (100%). The specifities were 100% for L. infantum and 98.5% for E. canis. The equivalence in sensitivity was confirmed by calculating the correlation coefficient between IFAT standards and mixed IFAT (r>or=0.99 for both pathogens). The results of our investigations demonstrated that mixed IFAT is a specific means of establishing serological differential diagnosis of canine leishmaniosis and ehrlichiosis.     

Comparison of results for serologic testing and a polymerase chain reaction assay to determine the prevalence of stray dogs in eastern Tennessee seropositive to Ehrlichia canis

OBJECTIVE: To determine the prevalence of stray dogs in eastern Tennessee seropositive to Ehrlichia canis and examine the correlation between results for an ELISA, indirect immunofluorescent antibody (IFA) test, and polymerase chain reaction (PCR) assay. SAMPLE POPULATION: Blood samples obtained from 90 adult dogs admitted to an animal shelter in eastern Tennessee. PROCEDURE: Serum samples were analyzed for antibodies against E. canis by use of a commercially available ELISA kit, 2 IFA tests, and a PCR assay; testing was performed at the University of Tennessee (TN) and North Carolina State University (NCSU). The PCR amplification was performed by use of DNA extracted from EDTA-anticoagulated blood and primers designed to amplify DNA of Ehrlichia spp. RESULTS: Antibodies against E. canis were detected in only 1 dog by use of the ELISA. By IFA testing at TN, 10 of 90 (11%) dogs were seroreactive against E. canis antigens, all of which had medium to high titers to E. canis. Only 5 of the 10 TN seroreactors were also reactive against E. canis antigens in IFA tests conducted at NCSU, and all 5 had low to medium titers. The DNA of Ehrlichia spp was not amplified in any blood samples by use of PCR assays conducted at the TN or NCSU. CONCLUSIONS AND CLINICAL RELEVANCE: The discordant ELISA, IFA, and PCR results obtained in this study were unexpected and may have been related to exposure of dogs to an Ehrlichia species other than E. canis, such as E. ewingii.