Diagnostic Accuracy of a Point-of-Care Immunoassay for Feline Immunodeficiency Virus Antibodies, Feline Leukemia Virus Antigen, and Dirofilaria immitis Antigen

Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are retroviral infections of cats worldwide whose clinical manifestations range from mild to severe disease. In both cases, infected cats can live a long life with proper care and should be managed to prevent infection of other cats. Dirofilaria immitis, the nematode that causes heartworm disease, can infect cats in any region where dogs are infected. Though cats are more resistant to infection, clinical diseases in the form of heartworm-associated respiratory disease can cause death. Screening for these infectious diseases enables veterinarians to manage their cases and prevent the spread to other cats. We describe the diagnostic accuracy of a point-of-care immunoassay for FIV, FeLV, and heartworm, compared to reference methods commonly available through reference laboratories to the practicing veterinarian. For FIV, we report 100% sensitivity (95% confidence limits (CL): 96.2-100%) and 97.8% specificity (95% CL: 95.4-99.4%). For FeLV, we report 100% sensitivity (95% CL: 97.7-100%) and 99.2% specificity (95% CL: 97.1-99.9%). And for heartworm, we report 90.2% sensitivity (95% CL: 76.9-97.3%) and 100% specificity (95% CL: 98.3-100%). Veterinarians may expect this performance relative to the reference methods they use for confirmatory serological testing.

Evaluation of Anaplasma spp. seroprevalence in dogs and association with incidence of human anaplasmosis

Point-of-care (POC) ELISA tests are routinely used in US veterinary practices to screen canine patients for antibodies to tick-transmitted pathogens. Results are also used to monitor spatial and temporal trends in canine seroprevalence, and these data can build awareness of the risk to humans of tick-transmitted diseases such as Lyme disease and anaplasmosis. This study utilized a second-generation test that has incorporated additional Anaplasma-specific peptides into a commercial POC ELISA test to allow detection of Anaplasma spp. antibodies earlier post-infection. A convenience population consisting of 19,894 canine samples from a US commercial diagnostic laboratory were tested using the second-generation POC ELISA test to describe regional Anaplasma spp. canine seroprevalence and assess correlation to anaplasmosis cases reported to Centers for Disease Control and Prevention by state. Antibodies to Anaplasma spp. were detected in 1646 samples (8.3%) with the Northeast and Midwest US census regions having the highest proportion of positive samples. At the state level, a significant correlation was found between canine Anaplasma spp. seroprevalence and human anaplasmosis incidence (r2 = 0.64). Although estimates of canine Anaplasma spp. seroprevalence presented here using the second-generation POC ELISA are generally increased, especially in the Northeast and Midwest, the regional distribution of canine samples testing positive for Anaplasma spp. antibodies is consistent with previous reports. The observed correlation with human anaplasmosis incidence indicates that results from the second-generation POC ELISA will continue to add value in epidemiological assessment of human anaplasmosis risk.

Use of In-Clinic Diagnostic Kits for the Detection of Seropositivity to Leishmania infantum and Other Major Vector-Borne Pathogens in Healthy Dogs

Canine Vector-Borne Diseases (CVBDs) are widespread in Europe and enzootic in many other countries. Though severe illnesses may occur, dogs living in enzootic areas often show vague or no clinical signs of CVBDs. Undiagnosed infections/co-infections in subclinically infected animals favor the spread of CVBDs and increase the risk of transmission to other animals and, in some cases, humans. This study has evaluated the exposure of dogs living in key enzootic countries, i.e., Italy and Greece, to major CVBDs via the use of in-clinic diagnostic kits. Overall, 300 privately owned dogs without/with single mild clinical signs living in different regions of Italy (n. 150) and Greece (n. 150) were included in the study. As part of a clinical examination, a blood sample was collected from each dog and subjected to two serological rapid tests, i.e., the SNAP^® 4Dx^®Plus (IDEXX Laboratories Inc.) for the detection of antibodies against Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi s.l. and Dirofilaria immitis antigen and the SNAP^®Leishmania (IDEXX Laboratories Inc.) for the detection of antibodies against Leishmania infantum. In all, 51 dogs (17%; 95% CI 12.9-21.7) were seropositive to at least 1 pathogen, i.e., 4 in Italy (2.7%; 95% CI 1.4-13.1) and 47 in Greece (31.3%; 95% CI 24-39.4). Dirofilaria immitis antigens were found in 39 dogs (13%; 95% CI 9.4-17.3), while antibodies against Ehrlichia, Anaplasma and Leishmania were detected in 25 (8.3%; 95% CI 5.5-12.1), 8 (2.7%; 95% CI 1.2-5.2) and 5 (1.7%; 95% CI 0.5-3.8) dogs, respectively. None of the dogs tested seropositive for B. burgdorferi s.l. Statistical analyses were performed to evaluate associations between exposure to CVBDs and possible risk factors. The present results indicate that dogs living in enzootic areas may be seropositive for one or more CVBDs in absence of clinical signs. Rapid kits are among first line tools for the detection of CVBDs in clinical settings, as they are cost-effective, straightforward and quick to use. Also, in-clinic tests used herein allowed detection of co-exposure to CVBDs investigated.

Vector-borne pathogens of zoonotic concern in hunting dogs of southern Italy

Dogs are commonly exposed to vector-borne pathogens (VBPs), yet few data are available on hunting dogs, which are often at high risk of infection due to their involvement in field activities. To investigate the occurrence of VBPs and evaluate the relative performance of different diagnostic tools, blood and serum samples were collected from hunting dogs (n = 1,433) in rural areas of southern Italy. All samples were tested by Knott's technique for filarioids, serologically (SNAP® 4Dx® Plus) for Anaplasma spp., Borrelia burgdorferi sensu lato, Dirofilaria immitis and Ehrlichia spp. and molecularly (qPCR) for all except B. burgdorferi of the above pathogens plus Babesia spp. and Leishmania infantum. Logistic regression was run to evaluate the statistical associations between the risk of VBP infection and independent variables (such as geographic area of provenience, age class and sex) and K-Cohen formula for assessing the concordance among diagnostic tests. Overall, out of 321 dogs (22.4%) positive to at least one VBP, 28 (1.9%) were infected by filarial species at the Knott's technique. In particular, Acanthocheilonema reconditum was the most prevalent (1.6%), followed by D. immitis (0.2%) and Dirofilaria repens (0.1%). One hundred forty (9.8%) and 231 (16.1%) dogs scored positive to VBPs by serological and molecular methods, respectively. The most prevalent pathogens detected were Ehrlichia spp. (7.3%) with SNAP® 4Dx® Plus, and A. reconditum (7.7%) by qPCR. Statistics revealed a significant association (p < 0.001) between A. reconditum infestation and both Ehrlichia spp. seropositivity and geographical origin of dogs. An agreement of 99.9%, 94.0% and 95.7% for Knott - SNAP® 4Dx® Plus, Knott - qPCR and SNAP® 4Dx® Plus - qPCR for D. immitis was found, respectively. Data demonstrate a high prevalence of VBPs in hunting dogs, indicating that this group of animals is largely exposed to several arthropod vector species and suggesting the transmission risk of pathogens to humans in rural areas of southern Italy. A multi-diagnostic approach and a deeper cooperation among healthcare and stakeholders are required to prevent VBP infections to animals and humans.

Associations between presence of Bartonella species deoxyribonucleic acid and complete blood cell count and serum biochemical changes in client-owned cats

Background

Infection with Bartonella species is common in cats but reported effects of bacteremia on laboratory variables differ.

Objectives

Evaluate for associations between Bartonella bacteremia and CBC and serum biochemical changes in sick and healthy cats throughout the United States.

Animals

A total of 3964 client‐owned cats.

Methods

Retrospective cohort study using submissions to a commercial laboratory between 2011 and 2017. Serum biochemistry and CBC abnormalities (categorized as above or below reference intervals), age, and location (high‐ or low‐risk state for Ctenocephalides felis) in presumed healthy and sick cats were evaluated for associations with presence of Bartonella spp. DNA, detected by PCR. Univariate and multivariable logistic regression analyses were performed.

Results

Bartonella spp. DNA was amplified from 127 (3.2%) of 3964 cats; 126 (99.2%) of 127 were from high flea risk states and 121 (95.3%) of 127 were presumed sick. Fever of unknown origin was the most common PCR panel requested. In the multivariable analysis, neutrophilia, decreased ALP activity, clinical status (presumed sick), and young age (≤2 years) each were positively associated whereas neutropenia and hyperproteinemia both were negatively associated with Bartonella spp. bacteremia. Presence of Bartonella spp. DNA had no association with test results for other infectious disease agents.

Conclusions and Clinical Importance

In both healthy and sick cats, active Bartonella infections had minimal association with clinically relevant laboratory abnormalities. However, based on these results, in areas considered high risk for C. felis, active infection with Bartonella spp. is a reasonable differential diagnosis for cats presented with unexplained fever and neutrophilia, particularly if the cat is young.

Bartonella spp. seroepidemiology and associations with clinicopathologic findings in dogs in the United States

Background

Improved understanding of Bartonella spp. serology in dogs may aid clinical decision making.

Objective

Describe demographic and geographic patterns of Bartonella spp. seroreactivity in dogs, and describe hematologic and serum biochemical abnormalities in Bartonella spp. seroreactive and nonseroreactive dogs.

Animals

Serum samples from 5957 dogs in the United States, previously submitted to IDEXX Reference Laboratories.

Methods

Serum was tested using 3 indirect ELISAs for B. henselae, B. vinsonii subsp. berkhoffii, and B. koehlerae. Complete blood count and serum biochemistry panel results were reviewed retrospectively.

Results

Overall, 6.1% of dogs were Bartonella spp. seroreactive. Toy breeds were less likely to be seroreactive (3.9%) than mixed breeds (7.5%; adjusted odds ratio [aOR], 0.48; 95% confidence interval [CI], 0.32‐0.72), and dogs <1 year old were less likely to be seroreactive (3.4%) than dogs 1 to 5.5 years of age (7.3%; aOR, 0.42; 95% CI, 0.23‐0.72). Dogs in the West South Central (9.8%) and South Atlantic (8.8%) regions were more likely than dogs elsewhere in the United States to be seroreactive (aOR, 2.22; 95% CI, 1.31‐3.87; aOR, 2.44; 95% CI, 1.38‐4.36).

Conclusions and Clinical Importance

Demographic and geographic findings for Bartonella spp. exposure were broadly comparable to previously reported patterns.

Evaluation for associations amongst Giardia duodenalis assemblages and diarrhea in dogs

Giardia duodenalis is a species complex comprising at least eight assemblages. Most dogs harbor the host-adapted assemblages C and D and approximately 30 % harbor the zoonotic assemblages. Humans and dogs with giardiosis can exhibit a variety of clinical manifestations ranging from the absence of clinical signs to acute or chronic diarrhea. Human studies report conflicting results concerning associations between clinical signs and assemblage type. The objective of this study was to use results of molecular and phylogenetic analyses to evaluate associations between G. duodenalis assemblages and diarrhea in client-owned dogs from the United States. Fecal samples that were positive for Giardia cysts were classified as normal or diarrheal. Samples were analyzed by PCR assays of the beta-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) genes. Sequences of the three genes were analyzed by BLAST analysis and phylogenetic analysis was performed by Neighbor-Joining analysis. Two hundred and eighty-eight Giardia-positive fecal samples were evaluated by the three PCRs. One or more genes were amplified from 95 normal samples and 93 diarrheal samples, 27 samples were positive for one or more genes but could not be sequenced due to low quality DNA, and 73 samples tested negative. Ninety seven percent of the samples (182/188) in both the diarrheal and normal groups typed as dog-specific assemblages (D or C) by at least one gene. Phylogenetic analysis of the three genes placed the isolates from assemblages A, B, C and D separated from each other with strong bootstrap support. Diarrhea was not associated with the Giardia assemblage or other parasitic co-infection in this sample set. Other factors, such as the role of gut microbiota in giardiosis should be considered in future studies.

Experimental infection of cats with Cryptosporidium felis

OBJECTIVES

The aims of this study were to experimentally inoculate cats with Cryptosporidium felis oocysts and compare fecal detection by fluorescent antibody assay (FA) and quantitative PCR (qPCR), and document clinical signs associated with infection.

METHODS

Cryptosporidium felis oocysts were concentrated from the feces of a naturally infected cat and orally inoculated into six cats that tested negative for C felis by an FA and fecal flotation (FF). Cats were observed daily for the presence of clinical signs consistent with infection. Fecal samples from all cats on days 0 and 9, and one sample per cat (days 18-21), were evaluated by all assays. On day 31, two cats negative for C felis by FF and FA were administered methylprednisolone acetate and all assays were repeated on days 34, 36 and 38. Samples from all cats were tested by FF and FA on days 41, 43, 45 and 48.

RESULTS

A total of 41 samples were tested, 25 of which were compared by FA and qPCR. Cryptosporidium felis was detected in 2/25 (8%) and in 19/25 (76%) samples by FA and by qPCR, respectively; the other 16 samples were tested by FF and FA. None of the cats was positive for C felis by FF or FA in samples collected on days 0, 9 or 18-21. One, five and six samples tested positive by qPCR on days 0, 9 and 18-21, respectively. The cats administered methylprednisolone acetate tested positive for C felis by FA on day 36 and by qPCR on days 31, 34, 36 and 38. None of the cats showed clinical signs of disease.

CONCLUSIONS AND RELEVANCE

Clinical signs were not recognized in any of the cats for the duration of the study. FA was insensitive compared with qPCR for detecting cats with subclinical C felis infection.

Prevalence of endoparasitic and viral infections in client-owned cats in metropolitan Bangkok, Thailand, and the risk factors associated with feline hookworm infections

The prevalence of enteric parasites in cats in metropolitan Bangkok has not been updated in over 13 years. The main objectives of this study include updating the prevalence of endoparasitism in client-owned cats, status of retroviral infections and determining the association between feline hookworm infection and possible risk factors. A total of 509 fecal samples were collected from client-owned cats in 2014-2015 and examined by a wet fecal mount technique. If additional sample remained, a PBS-ethyl acetate sedimentation was done (n = 229), and ZnSO₄ centrifugal flotation was also performed if there was sufficient remaining sample (n = 105). At least one parasite was observed in 32.0% (163/509) of cats, with Ancylostoma being the most common intestinal parasite detected in 21.6% (110/509) of cats. Other parasitic infections detected by fecal examinations included Toxocara (6.9%; 35/509), Platynosomum (3.7%; 19/509), Cystoisospora (3.5%; 18/509), Taenia (2.9%; 15/509), Spirometra (1.6%; 8/509), Dipylidium (0.4%; 2/509), and Opisthorchis-like trematode (0.2%; 1/509). Examination for Giardia infection was conducted with the SNAP® Giardia Test, a coproantigen test, on a subset of the fecal samples (233/509) and revealed a positive result on 3.9% (9/233) of samples. Plasma samples were analyzed using the SNAP® Triple Test detecting antigens of Feline Leukemia Virus (FeLV) and Dirofilaria immitis while also detecting antibodies to Feline Immunodeficiency Virus (FIV). Antigens of FeLV and antibodies to FIV were found in 7.1% (19/269) and 5.2% (14/269) of cats, respectively. None of the cats were found to have circulating antigen of Dirofilaria immitis using this test. No association between retroviral and endoparasitic infections was found. From multivariable logistic regression examining associated factors, the ability of cats to access the outdoors (adjusted OR = 3.22, 95% CI; 1.42-7.87) and having tapeworm segments or adult helminths in feces (adjusted OR = 3.31, 95% CI; 1.34-8.21) were significantly associated with the finding of hookworm eggs in feces. This work presents the most up-to-date data on enteric feline parasite prevalence in the metropolitan Bangkok area from which fecal samples were directly collected from cats. Consequently, this study emphasizes that diagnosis of parasitic infections and the routine use of antiparasitic medications should be encouraged by veterinarians and to owners in order to reduce the reservoir of potentially zoonotic parasites.

Emergence of Babesia conradae infection in coyote-hunting Greyhounds in Oklahoma, USA

BACKGROUND

Babesia species are intraerythrocytic Apicomplexan parasites that infect a wide range of vertebrate hosts. These pathogens are typically transmitted either by tick vectors or by direct blood-to-blood contact, and may cause life-threatening clinical disease, such as thrombocytopenia, hemolytic anemia and acute renal failure, in canine hosts. While Babesia vogeli and Babesia gibsoni infections have both been reported in Oklahoma, reports of Babesia conradae infections have been limited to California.

METHODS

Four separate kennels of coyote-hunting dogs were identified in Oklahoma after the kennels had consulted with Oklahoma State University Boren Veterinary Medical Teaching Hospital (antemortem cases) or the Oklahoma Animal Disease Diagnostic Lab (postmortem cases). Upon owner consent, every accessible dog from each of the four kennels was briefly examined for ectoparasites, particularly ticks, and whole blood samples were collected in EDTA tubes. Clinically ill dogs were examined by a practicing veterinarian, and clinical signs included anorexia, vomiting, lethargy, fever and anemia. DNA was extracted from each blood sample, and a nested PCR was performed using general apicomplexan primers for the partial 18S rRNA gene. PCR products were electrophoresed in agarose matrix, and appropriately sized amplicons were sequenced. Sequences were compared to reference 18S rRNA gene sequences available in GenBank, and samples with > 98% homology to B. conradae (GenBank: AF158702) were considered positive. Babesia conradae-positive dogs were then treated with atovaquone (13.5 mg/kg three times per day) and azithromycin (10 mg/kg once daily) for 10 days and retested at 30 and 60 days post-treatment by PCR.

RESULTS

Of 40 dogs tested, 15 (37.5%) were positive for B. conradae with 98-99% sequence homology to B. conradae from California. All positive cases were coyote-hunting Greyhounds. Ectoparasites were not identified on any of the dogs at the time of blood collection. Treatment of clinically ill dogs with atovaquone and azithromycin resulted in complete clinical recovery in all treated dogs with negative follow-up PCR at 30 and 60 days post-treatment.

CONCLUSIONS

Collectively, this study (i) documents the occurrence of B. conradae in Oklahoma, (ii) highlights this pathogen as a differential to be considered when clinical signs are present, (iii) supports the use of atovaquone and azithromycin as effective treatment in these cases and (iv) demonstrates chronic subclinical carrier dogs serving as potential reservoirs of B. conradae infection to naïve dogs.

Major antigen and paramyosin proteins as candidate biomarkers for serodiagnosis of canine infection by zoonotic Onchocerca lupi

Onchocerca lupi (Spirurida: Onchocercidae) is a filarial worm parasitizing domestic carnivores and humans. Adult nematodes usually localize beneath in the sclera or in the ocular retrobulbar of infected animals, whilst microfilariae are found in the skin. Therefore, diagnosis of O. lupi is achieved by microscopic and/or molecular detection of microfilariae from skin biopsy and/or surgical removal of adults from ocular tissues of infected hosts. An urgent non-invasive diagnostic tool for the diagnosis of O. lupi in dog is mandatory. In this study, an immunoproteomic analyses was performed using a combination of immunoblotting and mass spectrometry techniques. Onchocerca lupi major antigen (Ol-MJA) and paramyosin (Ol-PARA) proteins were identified as potential biomarkers for serodiagnosis. Linear epitopes were herein scanned for both proteins using high-density peptide microarray. Sera collected from dog infected with O. lupi and healthy animal controls led to the identification of 11 immunodominant antigenic peptides (n = 7 for Ol-MJA; n = 4 for Ol-PARA). These peptides were validated using sera of dogs uniquely infected with the most important filarioids infesting dogs either zoonotic (Dirofilaria repens, Dirofilaria immitis) or not (Acanthocheilonema reconditum and Cercopithifilaria bainae). Overall, six antigenic peptides, three for Ol-MJA and for Ol-PARA, respectively, were selected as potential antigens for the serological detection of canine O. lupi infection. The molecular and proteomic dataset herein reported should provide a useful resource for studies on O. lupi toward supporting the development of new interventions (drugs, vaccines and diagnostics) against canine onchocercosis.

The diagnosis of Onchocerca lupi (Spirurida: Onchocercidae), a zoonotic nematode of domestic animals, is currently based on microscopic examination of skin snip sediments and on the identification of adults embedded in ocular nodules or by molecular assays. An urgent non-invasive diagnostic tool for the diagnosis of O. lupi in dogs is mandatory. In this context, combined immunoblotting and mass spectrometry-based analyses have been performed to identify two proteins, major antigen and paramyosin, of O. lupi. Peptides herein identified represent suitable candidate biomarker for the development of a specific diagnostic test for canine onchocercosis. An accurate, minimally invasive diagnostic method could prove useful for the control of the canine diseases, for establishing large sero-surveys, for mapping the distribution of the infection in endemic areas as well as in areas where information on the disease is not available and for the reduction of risks for human infection.

Systemic inflammatory response syndrome in dogs naturally infected with Babesia canis: Association with the parasite load and host factors

The common signs of canine babesiosis caused by an infection with Babesia canis are fever, anorexia, lethargy, pulse alterations, anemia, and occasionally mild icterus. Dogs with these clinical signs can be divided into two groups: those with acute-phase reaction and those with systemic inflammatory response syndrome (SIRS). Factors associated with the occurrence of SIRS in canine babesiosis have not been thoroughly researched. This article outlines a cross-sectional study of 54 client-owned dogs with an acute B. canis infection, and evaluates the differences in age, gender, laboratory findings, parasite load, and seroreactivity against B. canis between the SIRS and the SIRS-free dogs. We have analyzed a complete blood count, serum biochemistry, serum amyloid A, ceruloplasmin, paraoxonase-1, serology, and PCR testing using standard methodologies. The frequency of SIRS among the investigated dogs reached 0.59. Male dogs and those seronegative against B. canis, were more frequent in the SIRS group, whilst age and parasite load could not be associated with the presence of SIRS. Dogs with SIRS had a lower count of total leukocytes, neutrophils, lymphocytes, and monocytes, and a lower concentration of iron and bilirubin compared with SIRS-free dogs. No significant differences in the concentration of acute-phase proteins have been noticed to exist between the groups of dogs. Further, the seronegative dogs had a lower count of lymphocytes and monocytes and a higher parasite load than the seroreactive dogs. Multivariate logistic regression analysis has identified leukopenia (<6 × 10⁹/L) and monocytopenia (<0.2 × 10⁹/L) as independent associates of SIRS in the investigated dogs, thus implying that these routine tests could be used as reliable markers for SIRS.

Comparison of Anaplasma and Ehrlichia species-specific peptide ELISAs with whole organism-based immunofluorescent assays for serologic diagnosis of anaplasmosis and ehrlichiosis in dogs

OBJECTIVE

To compare the performance of 5 synthetic peptide-based ELISAs with that of 3 commercially available immunofluorescent assays (IFAs) for serologic diagnosis of anaplasmosis and ehrlichiosis in dogs.

SAMPLE

A convenience set of 109 serum samples obtained before and at various times after inoculation for 23 dogs that were experimentally infected with Anaplasma phagocytophilum, Anaplasma platys, Ehrlichia canis, Ehrlichia chaffeensis, or Ehrlichia ewingii and 1 uninfected control dog in previous studies.

PROCEDURES

All serum samples were assessed with 5 synthetic peptide-based ELISAs designed to detect antibodies against A phagocytophilum, A platys, E canis, E chaffeensis, and E ewingii and 3 whole organism-based IFAs designed to detect antibodies against A phagocytophilum, E canis, and E chaffeensis. The species-specific seroreactivity, cross-reactivity with the other tick-borne pathogens (TBPs), and diagnostic sensitivity and specificity were calculated for each assay and compared among assays.

RESULTS

All serum samples obtained from dogs experimentally infected with a TBP yielded positive results on a serologic assay specific for that pathogen. In general, sensitivity was comparable between ELISAs and IFAs and tended to increase with duration after inoculation. Compared with the IFAs, the corresponding ELISAs were highly specific and rarely cross-reacted with antibodies against other TBPs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that peptide-based ELISAs had enhanced specificity relative to whole organism-based IFAs for detection of antibodies against Anaplasma and Ehrlichia spp, which should facilitate accurate diagnosis and may help detect dogs coinfected with multiple TBPs.

Experimental infection of cats with Cystoisospora felis

Background

Cystoisospora felis is a common parasite of cats and is diagnosed by fecal flotation, but false‐negative results can be common.

Hypothesis/Objectives

To experimentally inoculate cats with C. felis oocysts, to compare fecal flotation and polymerase chain reaction (PCR) results, and to describe any clinical signs consistent with infection.

Animals

Six cats.

Methods

Cystoisospora felis oocysts were identified morphologically from feces of a naturally infected kitten with diarrhea, sporulated oocysts (5000) were inoculated to 6 cats that were negative for fecal parasites by fecal flotation and by a fluorescent antibody assay (FA) for Giardia spp. and Cryptosporidium spp. Cats were observed daily for the presence of clinical signs consistent with infection. Fecal samples were evaluated by fecal flotation and FA up to 3 times per week post inoculation (PI) to Day 27. Thirty‐six samples collected before inoculation and from Days 8, 10, 13, 15, and 20 PI were assayed using an internal transcribed spacer 1 (ITS1) PCR that amplifies DNA of C. felis.

Results

All cats were negative for C. felis by both assays before inoculation. All cats shed C. felis oocysts by Day 10 PI, oocysts were not detected by fecal flotation after Day 15 PI. Cystoisospora felis DNA was amplified from 24/36 (66.6%) fecal samples from 6/6 (100%) of the cats. Oocysts were not detected by fecal flotation in 4 of the samples that were positive for C. felis DNA by PCR. Clinical signs were not recognized in any of the study cats.

Conclusions and Clinical Importance

Fecal flotation is a convenient assay for detection of C. felis but could occasionally give false‐negative results when compared to this ITS1 PCR.

Distribution and risk factors of canine haemotropic mycoplasmas in hunting dogs from southern Italy

Mycoplasma haemocanis (Mhc) and "Candidatus Mycoplasma haematoparvum" (CMhp) are the main haemoplasma species known to infect dogs. The aim of this study was to determine the prevalence of haemoplasma species infections in hunting dogs from southern Italy and assess related risk factors. 1,433 hunting dogs living in Campania region were tested by qPCR assay. The prevalence was 19.9 %; 13.1 % for Mhc and 11.4 % for CMhp; 4.6 % showed a coinfection with both haemoplasma species. Statistical analysis revealed living in Salerno province (Mhc: OR 3.72; CMhp: OR 2.74), hound (Mhc: OR 5.26; CMhp: OR 8.46) and mixed breed (Mhc: OR 3.38; CMhp: OR 2.80), rural environment (Mhc: OR 12.58; CMhp: OR 10.38), wild mammal hunting (Mhc: OR 8.73; CMhp: OR 8.32), cohabitation with other animals (Mhc: OR 2.82; CMhp: OR 2.78) and large pack size (Mhc: OR 2.96; CMhp: OR 1.61) as risk factors for haemoplasmas. Male gender (OR 1.44) and tick infestation history (OR 1.40) represented risk factors only for Mhc, while adult age (2-7 years - OR 2.01; > 7 years - OR 1.84) and large body size (OR 1.48) were associated only to CMhp. Mhc infection was significantly associated to Babesia vogeli (p < 0.05) and Hepatozoon canis (p < 0.001), while CMhp with H. canis (p < 0.001). This study adds information on haemoplasma species distribution in hunting dogs in southern Italy. Outdoor lifestyle and contact with wild fauna, through greater exposure to tick infestation, or possibly wounds acquired during hunting or fighting, could be factors contributing to haemoplasma infections.

Global distribution of canine Babesia species identified by a commercial diagnostic laboratory

Babesia species are important canine pathogens with a nearly worldwide distribution. Our understanding of the distribution of these parasites is continually improving. This is in large part, due to improved molecular diagnostic capabilities. However, it can be difficult to assimilate and compare previous reports from various regions due to differences in molecular methods. In this report, we characterize the results of over 100,000 canine samples from 52 different countries and territories spanning 4 continents that were submitted to a commercial diagnostic laboratory for Babesia testing by polymerase chain reaction. The same diagnostic algorithm was used for all samples and is designed to identify and differentiate B. gibsoni, B. canis, B. vogeli, B. rossi and B. conradae. Overall 3.4% of the samples submitted tested positive for the presence of Babesia sp. DNA and were differentiated to the species level. Babesia gibsoni was the most commonly identified species (48.8% of the positive results) followed by B. canis (35.2%) then B. vogeli (15.3%). Babesia gibsoni and B. vogeli were more widely distributed than B. canis, which was primarily found in Europe. This is the largest study of its type and these data provide a global overview of which Babesia species veterinarians could expect to find in their practice area.

Heartworm control in Grenada, West Indies: Results of a field study using imidacloprid 10% + moxidectin 2.5% and doxycycline for naturally-acquired Dirofilaria immitis infections

Canine heartworm disease (CHD) results from infection with Dirofilaria immitis and while it is of global concern, it is most prevalent in tropical climates where conditions support the parasite and vector life cycles. Melarsomine dihydrochloride is the sole treatment for CHD recommended by the American Heartworm Society. However, in cases where cost or access to melarsomine precludes treatment of an infected dog, therapeutic alternatives are warranted. This randomized, controlled field study evaluated the adulticidal efficacy of a combination therapeutic protocol using 10 % imidacloprid + 2.5 % moxidectin spot-on and a single 28-day course of doxycycline and compared with that of a 2-dose melarsomine dihydrochloride protocol. Of 37 naturally-infected domestic dogs with class 1, 2 or early class 3 CHD enrolled in the study, 30 were evaluated for a minimum of 12 months. Seven dogs were withdrawn due to canine ehrlichiosis, non-compliance, or wrongful inclusion. Dogs were randomly assigned to a control (CP, n = 15) or investigational (IVP, n = 15) treatment group. CP dogs received two injections of melarsomine dihydrochloride (2.5 mg/kg) 24 -hs apart and maintained on monthly ivermectin/pyrantel. IVP dogs were treated with oral doxycycline (10 mg/kg twice daily for 28 days) and topical 10 % imidacloprid + 2.5 % moxidectin once monthly for 9 months. Dogs were evaluated up to 18 months - monthly for the first 9 months, then every 3 months. Parasiticidal efficacy was based on antigen status using the IDEXX PetChek® 34 Heartworm-PF Antigen test. By month 18, antigen was not detected in any study dog except one from the IVP group. One other IVP dog was persistently antigenemic and treated with melarsomine at month 12 according to the initial study protocol. Mean antigen concentration (based on optical density) decreased more rapidly in the CP group and by month 15 was 0.11 for the IVP and 0.07 for CP groups, with equivalent median concentrations (0.04) in both groups. Conversion following heat-treatment of antigen-negative samples occurred frequently and at similar rates in both treatment groups. Based on the bias of diagnostic tests towards detection of female worms, we conclude that monthly application of 10 % imidacloprid + 2.5 % moxidectin for 9 months combined with a course of doxycycline twice daily for 28 days resulted in effective therapy against female adults in CHD. This therapeutic option may be particularly useful in cases where financial constraint or access to melarsomine precludes treatment of an infected individual. This study was supported by Bayer Animal Health.

Hepatozoon canis in hunting dogs from Southern Italy: distribution and risk factors

Hepatozoon canis is a hemoprotozoan organism that infects domestic and wild carnivores throughout much of Europe. The parasite is mainly transmitted through the ingestion of infected ticks containing mature oocysts. The aims of the present survey were to determine the prevalence of H. canis in hunting dogs living in Southern Italy and to assess potential infection risk factors. DNA extracted from whole blood samples, collected from 1433 apparently healthy dogs living in the Napoli, Avellino, and Salerno provinces of Campania region (Southern Italy), was tested by a quantitative real-time polymerase chain reaction (qPCR) assay to amplify H. canis. Furthermore, the investigated dog population was also screened by qPCR for the presence of Ehrlichia canis, a major tick-borne pathogen in Southern Italy, in order to assess possible co-infections. Two hundred dogs were H. canis PCR-positive, resulting in an overall prevalence of 14.0% (CI 12.2–15.9). Breed category (P < 0.0001), hair coat length (P = 0.015), and province of residence (P < 0.0001) represented significant risk factors for H. canis infection. The presence of H. canis DNA was also significantly associated with E. canis PCR positivity (P < 0.0001). Hunting dogs in Campania region (Southern Italy) are frequently exposed to H. canis, and the infection is potentially associated with close contact with wildlife. Further studies are needed to assess the pathogenic potential of H. canis, as well as the epidemiological relationships between hunting dogs and wild animal populations sharing the same habitats in Southern Italy.

Predominant risk factors for tick-borne co-infections in hunting dogs from the USA

Background

Both incidence and geographical range of tick-borne disease has increased across the USA. Similar to people, dogs are hosts for Anaplasma spp., Babesia spp., Ehrlichia spp. and Borrelia burgdorferi. Dogs also share our homes and beds, making them both a sentinel for the ticks in our backyards but also increasing our exposure to ticks. Measures to better track, prevent, and/or treat tick-borne diseases in companion animals can lead to better control and prevention of human tick-borne disease. This study identifies demographic and co-infection risk factors for canine seropositivity to tick-borne infections in a cohort of hunting dogs across the USA.

Results

Human patterns of tick-borne disease co-infection in the USA have been predominantly driven by the geographical distribution of the tick vector. Dogs who tested seropositive for Anaplasma spp. were 1.40 times more likely (P = 0.0242) to also test seropositive for Babesia spp. and vice versa (1.60 times more likely, P = 0.0014). Dogs living in the West had 5% lower risk (P = 0.0001) for Ehrlichia spp. seropositivity compared to other regions. Controlling for age and Anaplasma spp. seroprevalence, dogs in all three other regions were 2.30 times more likely (P = 0.0216) to test seropositive for B. burgdorferi than dogs in the West. Dogs seropositive for B. burgdorferi were 1.60 times more likely (P = 0.0473) to be seropositive for Anaplasma spp.

Conclusions

Tick geographical distributions have a prominent impact on the regional distribution of hunting dog exposure to tick-borne diseases. Education concerning regional tick prevalence and disease risk is important for everyone, but particularly dog owners, regarding ticks in their region and protection from infection and co-infection of tick-borne pathogens as they travel or move with their dogs. Dogs are sentinel species for human exposure to ticks, and as such surveillance of canine tick-borne infections and understanding the probability that these infections might be seen together as co-infections helps predict emerging areas where people are more likely to be exposed as well.

Detection of Bartonella spp. in dogs after infection with Rickettsia rickettsii

Background

Dynamics of infection by Bartonella and Rickettsia species, which are epidemiologically associated in dogs, have not been explored in a controlled setting.

Objectives

Describe an outbreak investigation of occult Bartonella spp. infection among a group of dogs, discovered after experimentally induced Rickettsia rickettsii (Rr) infection.

Animals

Six apparently healthy purpose‐bred Beagles obtained from a commercial vendor.

Methods

Retrospective and prospective study. Dogs were serially tested for Bartonella spp. and Rr using serology, culture, and PCR, over 3 study phases: 3 months before inoculation with Rr (retrospective), 6 weeks after inoculation with Rr (retrospective), and 8 months of follow‐up (prospective).

Results

Before Rr infection, 1 dog was Bartonella henselae (Bh) immunofluorescent antibody assay (IFA) seroreactive and 1 was Rickettsia spp. IFA seroreactive. After inoculation with Rr, all dogs developed mild Rocky Mountain spotted fever compatible with low‐dose Rr infection, seroconverted to Rickettsia spp. within 4‐11 days, and recovered within 1 week. When 1 dog developed ear tip vasculitis with intra‐lesional Bh, an investigation of Bartonella spp. infection was undertaken. All dogs had seroconverted to 1‐3 Bartonella spp. between 7 and 18 days after Rr inoculation. Between 4 and 8 months after Rr inoculation, Bh DNA was amplified from multiple tissues from 2 dogs, and Bartonella vinsonii subsp. berkhoffii (Bvb) DNA was amplified from 4 of 5 dogs' oral swabs.

Conclusions and Clinical Importance

Vector‐borne disease exposure was demonstrated in research dogs from a commercial vendor. Despite limitations, our results support the possibilities of recrudescence of chronic subclinical Bartonella spp. infection after Rr infection and horizontal direct‐contact transmission between dogs.

Molecular identification of vector-borne organisms in Ehrlichia seropositive Nicaraguan horses and first report of Rickettsia felis infection in the horse

Certain vector-borne organisms serve as etiological agents of equine disease. After previously identifying a new Ehrlichia species in horses from Mérida, we aimed to determine the infection frequency and screen for a wide range of vector-borne organisms from 93 tick-exposed, Ehrlichia seropositive horses in this region. PCR assays were performed to identify infection by organisms within the following genera: Anaplasma, Babesia, Bartonella, Ehrlichia, Leishmania, Mycoplasma, Neorickettsia, Rickettsia and Theileria. Overall, 90/93 horses (96.8%) were infected with one or more vector-borne organisms. Ninety (96.8%) horses were infected with Theileria equi and 21 (26.8%) with Babesia caballi. Nine (9.7%) horses were infected with the novel Ehrlichia species previously designated H7, reported in horses from Nicaragua and Brazil. Two horses (2.2%) were infected with Rickettsia felis. Anaplasma, Bartonella, Leishmania, Mycoplasma, or Neorickettsia species DNA was not amplified from any horse. Ticks collected from horses infected with vector-borne organisms were identified as Amblyomma cajennense sensu lato and Dermacentor nitens. Horses in Mérida are infected by a range of vector-borne organisms, including B. caballi, T. equi, Ehrlichia species H7, and R. felis. To the authors' knowledge, this constitutes the first report of molecular detection of R. felis in horses.

Borrelia burgdorferi Antibody Test Results in Dogs Administered 4 Different Vaccines

Vaccines against Borrelia burgdorferi are administered frequently to dogs in areas endemic for the infection. These vaccines produce an antibody response to spirochetal proteins that cross-react in many antibody tests, including immunofluorescence assay, Western blot, and whole cell ELISA used to document exposure to B. burgdorferi. The purpose of this study was to determine whether the in-clinic C6 ELISA assay (SNAP® 4Dx® Plus; IDEXX Laboratories, Inc., Westbrook, Maine) and the quantitative format C6 ELISA (Lyme Quant C6® Antibody Test, IDEXX Laboratories, Inc., Westbrook, ME) react to sera from dogs that have been vaccinated with 1 of 4 different commercially available B. burgdorferi vaccines. Four groups of 3 dogs each were each administered one of the 4 vaccines and sera evaluated over time by indirect fluorescent antibody assay, western blot immunoassay, the in-clinic C6 ELISA assay, and the quantitative format C6 ELISA. While all dogs developed B. burgdorferi antibodies detectable by indirect fluorescent antibody assay and western blot immunoassay after vaccination, none of the samples were positive in either of the C₆ peptide-based assays. Based on these results, positive anti-C₆ antibody results in client-owned dogs are likely to reflect exposure to B. burgdorferi rather than vaccination.

Distribution of the feline lungworm Aelurostrongylus abstrusus in the USA based on fecal testing

Objectives

The aim of this study was to compile commercial reference laboratory data over a 10-year period to determine the distribution of Aelurostrongylus abstrusus, commonly known as feline lungworm, within the USA based on widespread fecal testing in cats.

Methods

The results of 3,610,455 feline ova and parasite (O&P) zinc sulfate centrifugation fecal flotation tests performed at IDEXX Reference Laboratories in the USA from January 2008 to December 2017 were compiled and sorted for tests positive for A abstrusus larvae. The results of 3625 Baermann tests, currently considered the gold standard diagnostic for feline lungworm, were also retrieved from the same period.

Results

Of the tests performed, 4721 (0.13%) feline O&P zinc sulfate centrifugation fecal flotation tests and 75 (2.07%) of the Baermann tests conducted were positive for the presence of A abstrusus larvae. The O&P data revealed a significant association between infection status and sex, while male cats in both the O&P and Baermann data sets had a higher risk of A abstrusus infection than females. Significant variation in positive rates were observed by region and most positive cases were clustered in the Northeast, Midwest and West regions of the USA.

Conclusions and relevance

This study highlights the distribution of feline lungworm in the USA and the limitations of using current testing to diagnose this infection. The introduction of higher throughput, less labor-intensive diagnostic methods could help increase awareness of this parasite among veterinary professionals, achieve a greater understanding of epidemiological factors, and improve the care and treatment for clinically ill feline patients.

Association of acute Babesia canis infection and serum lipid, lipoprotein, and apoprotein concentrations in dogs

BACKGROUND

Babesia canis infection induces a marked acute phase response (APR) that might be associated with alteration in lipid and lipoprotein metabolism and disease prognosis.

HYPOTHESIS

Dogs with B. canis-induced APR develop dyslipidemia with altered lipoprotein concentration and morphology.

ANIMALS

Twenty-nine client-owned dogs with acute B. canis infection and 10 clinically healthy control dogs.

METHODS

Observational cross-sectional study. Serum amyloid A (SAA) was measured using ELISA. Cholesterol, phospholipids, and triglycerides were determined biochemically. Lipoproteins were separated using agarose gel electrophoresis. Lipoprotein diameter was assessed by polyacrylamide gradient gel electrophoresis; correlation with ApoA-1 (radioimmunoassay) and SAA was determined.

RESULTS

Dogs with B. canis infection had a marked APR (median SAA, 168.3 μg/mL; range, 98.1-716.2 μg/mL) compared with controls (3.2 μg/mL, 2.0-4.2 μg/mL) (P < .001). Dogs with B. canis infection had significantly lower median cholesterol (4.79 mmol/L, 1.89-7.64 mmol/L versus 6.15 mmol/L, 4.2-7.4 mmol/L) (P = .02), phospholipid (4.64 mmol/L, 2.6-6.6 mmol/L versus 5.72 mmol/L, 4.68-7.0 mmol/L) (P = .02), and α-lipoproteins (77.5%, 27.7%-93.5% versus 89.2%, 75.1%-93.5%) (P = .04), and higher ApoA-1 (1.36 U, 0.8-2.56 U versus 0.95 U, 0.73-1.54 U) concentrations (P = .02). Serum amyloid A correlated with high-density lipoproteins (HDLs) diameter (rho = .43; P = .03) and ApoA-1 (rho = .63, P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Major changes associated with B. canis-induced APR in dogs are related to concentration, composition, and morphology of HDL particles pointing to an altered reverse cholesterol transport. Parallel ApoA-1 and SAA concentration increase is a unique still unexplained pathophysiological finding.

Prevalence and risk factors for selected canine vector-borne diseases in Greece

Background

Canine vector-borne diseases (CVBDs) represent a wide group of diseases of major significance for canine health. In addition to their veterinary importance, many of these diseases are of great zoonotic concern, posing a risk of potential transmission to humans. To date, there has been scant knowledge regarding the prevalence, distribution and risk factors of CVBDs in Greece. Therefore, the objectives of the present study were to update the current knowledge on the seroprevalence of Dirofilaria immitis, Anaplasma spp., Ehrlichia spp. and Borrelia burgdorferi (sensu lato) in dogs in Greece and, furthermore, to assess possible environmental and any other risk factors associated with these infections. A total of 1000 apparently healthy and randomly selected dogs, presented in veterinary clinics, were involved at the national level (n = 66 municipalities). Serum samples were obtained from each individual dog and were tested using the SNAP^® 4Dx^® Plus kit from IDEXX Laboratories. Possible risk factors were assessed using binary regression models, including dogs’ lifestyle, climatological parameters and the altitude of the region.

Results

Overall, 21.8% (95% CI: 19.4–24.5%) of the sampled dogs were found to be seropositive to at least one of the four pathogens examined. The most prevalent pathogen was Ehrlichia spp. (12.5%, 95% CI: 10.6–14.7) followed by D. immitis (9.0%, 95% CI: 7.8–11.5) and Anaplasma spp. (6.2%, 95% CI: 4.9–7.9). The lowest prevalence (0.1%) was recorded for B. burgdorferi (s.l.) where only one dog was found to be positive. Among the examined risk factors, low mean temperature was found to increase the prevalence of Ehrlichia spp. (P ≤ 0.001) and Anaplasma spp. (P ≤ 0.001), while low minimum temperature increased the prevalence of D. immitis (P ≤ 0.001). In addition, low total annual rainfall had an effect of the prevalence of Ehrlichia spp. (P ≤ 0.01). Altitude also had a significant effect on the prevalence of D. immitis (P ≤ 0.05) and Anaplasma spp. (P ≤ 0.01).

Conclusions

To our knowledge, this is the first large-scale seroepidemiological study of CVBDs in Greece. It has been evidenced that environmental factors such as temperature, rainfall and altitude can influence the prevalence and distribution of CVBDs.

Prevalence of Borrelia burgdorferi, Anaplasma spp., Ehrlichia spp. and Dirofilaria immitis in Canadian dogs, 2008 to 2015: a repeat cross-sectional study

Background

Vector-borne pathogens are emerging concerns in multiple regions of Canada. Determining regional prevalence of canine vector-borne pathogens and documenting change will improve clinician awareness, enable targeted prevention, enhance diagnosis and ideally reduce the risk of disease. Study objectives were to: (i) estimate the prevalence of positive canine vector-borne test results from samples submitted in Canada; (ii) assess change in prevalence over time, from baseline (2008) to 2015; and (iii) estimate the prevalence of pathogen co-infections.

Methods

This repeat cross-sectional study evaluated 753,468 test results for D. immitis antigen and B. burgdorferi, Ehrlichia canis/ewingii/muris serology, and 753,208 test results for Anaplasma phagocytophilum/platys serology using the SNAP® 4Dx®Test and SNAP 4Dx® Plus Test.

Results

Based on all submitted samples from Canada (2008–2015), the period seroprevalence of B. burgdorferi, Ehrlichia spp., Anaplasma spp. and D. immitis antigen were 2.0%, 0.5%, 0.4% and 0.2%, respectively. Over the 7 years (2008 compared to 2015) we observed a significant increase in seroprevalence for B. burgdorferi (144.4%) and Ehrlichia spp. (150%). Co-infections (positive for two or more pathogens on a single 4 pathogen test kit) were estimated at 5.4% (1162/21,612) of total positive tests.

Conclusions

The temporal rise and geographical differences in prevalence detected for these pathogens (notably B. burgdorferi) are consistent with anecdotal information on canine illness related to tick-borne pathogen exposure in multiple regions of Canada, particularly canine Lyme disease.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3299-9) contains supplementary material, which is available to authorized users.

Comorbid infections induce progression of visceral leishmaniasis

BACKGROUND

Visceral leishmaniasis (VL) is a vector borne zoonotic disease endemic in humans and dogs in Brazil. Due to the increased risk of human infection secondary to the presence of infected dogs, public health measures in Brazil mandate testing and culling of infected dogs. Despite this important relationship between human and canine infection, little is known about what makes the dog reservoir progress to clinical illness, significantly tied to infectiousness to sand flies. Dogs in endemic areas of Brazil are exposed to many tick-borne pathogens, which are likely to alter the immune environment and thus control of L. infantum.

RESULTS

A cross-sectional study of 223 dogs from an area of Natal, in the Rio Grande do Norte, Brazil, were studied to determine the association between comorbid tick-borne disease and Leishmania infection in this endemic area. The risk of Leishmania seropositivity was 1.68× greater in dogs with tick-borne disease seropositivity compared to those without (Adjusted RR: 1.68, 95% CI: 1.09-2.61, P = 0.019). A longitudinal study of 214 hunting dogs in the USA was conducted to determine the causal relationship between infection with tick-borne diseases and progression of VL. Hunting dogs were evaluated three times across a full tick season to detect incident infection with tick-borne diseases. A logistic regression model with generalized estimating equations to estimate the parameters was used to determine how exposure to tick-borne disease altered VL progression over these three time points when controlling for other variables. Dogs infected with three or more tick-borne diseases were 11× more likely to be associated with progression to clinical VL than dogs with no tick-borne disease (Adjusted RR: 11.64, 95% CI: 1.22-110.99, P = 0.03). Dogs with exposure to both Leishmania spp. and tick-borne diseases were five times more likely to die during the study period (RR: 4.85, 95% CI: 1.65-14.24, P = 0.0051).

CONCLUSIONS

Comorbid tick-borne diseases dramatically increased the likelihood that a dog had clinical L. infantum infection, making them more likely to transmit infection to sand flies and people. As an important consequence, reduction of tick-borne disease exposure through topical or oral insecticides may be an important way to reduce progression and transmissibility of Leishmania infection from the canine reservoir to people.

Clinicopathological findings in 41 dogs (2008-2018) naturally infected with Ehrlichia ewingii

Background

Ehrlichia ewingii is the most seroprevalent Ehrlichia‐infecting dogs in the southern and mid‐western United States. Fever, lameness, and polyarthritis are commonly reported findings in dogs naturally infected with E. ewingii.

Objectives

To evaluate clinicopathologic findings in a population of dogs naturally infected with E. ewingii.

Animals

Forty‐one dogs PCR positive for E. ewingii and PCR negative for other targeted vector‐borne organisms.

Methods

Retrospective study. Clinical and clinicopathologic data including physical examination findings, CBC, serum biochemistry, urinalysis (UA), symmetric dimethylarginine (SDMA), and vector‐borne disease diagnostic results were reviewed.

Results

Frequent clinical diagnoses other than ehrlichiosis (28/41; 68.3%) were renal disease (7/41; 17.1%) and immune‐mediated hemolytic anemia (IMHA) (6/41; 14.6%). The most frequent physical examination finding was joint pain (14/41; 34.1%). Prominent hematologic and biochemical abnormalities included abnormal lymphocyte counts (22/36; 61.1%); neutrophilia (21/37; 56.8%); increased alkaline phosphatase (20/35; 57.1%) and alanine transaminase (14/35; 40%) activities; and increased SDMA concentration (11/34; 32.4%). Urinalysis abnormalities included proteinuria (20/27; 74%), most with inactive sediments (16/20; 80%). Dogs were seroreactive by Ehrlichia canis immunofluorescence assay (IFA; 17/39; 43.6%) and Ehrlichia ELISA (34/41; 82.9%). Seroreactivity by IFA for other vector‐borne pathogens included Bartonella (1/39; 2.6%), Rickettsia rickettsii (spotted‐fever group rickettsiae) (12/39; 30.8%), and Borrelia burgdorferi by ELISA (1/41; 2.4%).

Conclusions and Clinical Importance

Renal disease, IMHA, proteinuria, neutrophilia, abnormal lymphocytes, and increased liver enzyme activities were common in this group of E. ewingii‐infected dogs. Studies are needed to determine if E. ewingii contributes to comorbidities or is a precipitating factor in clinical syndromes in persistently infected dogs.

Molecular and Serological Prevalence of Anaplasma phagocytophilum, A. platys, Ehrlichia canis, E. chaffeenses, E. ewingii, Borrelia burgdorferi, Babesia canis, B. gibsoni and B. vogeli among Clinically Healthy Outdoor Dogs in Serbia

Data concerning combined molecular and serological prevalence of emerging canine tick-borne pathogens in Serbia are lacking. A large population of outdoor living dogs in Belgrade, Serbia's' capital, present an excellent population for epidemiology study. Blood samples were collected from 111 dogs, including 46 shelter, 31 free roaming, and 34 hunting dogs. Species-specific real-time polymerase chain reaction (PCR) (IDEXX Laboratories, Inc., Westbrook Maine, USA) was applied for the molecular detection of Anaplasma phagocytophilum, A. platys, Ehrlichia canis, Babesia canis, B. gibsoni and B. vogeli. A research based SNAP assay (SNAP® M-A, IDEXX Laboratories, Inc., Westbrook Maine, USA) that uses genus and species-specific peptides was used to asses Anaplasma spp., A. phagocytophilum, A. platys, Ehrlichia spp., E. canis, E. chaffeensis, E. ewingii and Borrelia burgdorferi antibody status. B. canis, B. gibsoni and B. vogeli antibody status was assessed with an indirect immunofluorescence test (MegaCor Diagnostic, Horbranz, Austria). Anaplasma spp. and Ehrlichia spp. DNA was not amplified. One quarter of the dogs were A. phagocytophilum, one dog was A. platys, one was E. ewingii and two dogs were B. burgdorferi seroreactive with the SNAP® M-A. Babesia canis or B. gibsoni DNA was amplified by PCR from 16.2% of dogs, whereas 67.6% were seroreactive to one or more Babesia spp. Babesia vogeli was not PCR amplified. We conclude that outdoor dogs in this territory are reservoirs for B. canis and B. gibsoni and are frequently co-exposed to combinations of Anaplasma and Babesia spp.

Evidence for Clinical Anaplasmosis and Borreliosis in Cats in Maine

The objectives of this study were to use data from client-owned cats in an Ixodes scapularis endemic area to evaluate for clinical associations with diagnostic test results for Anaplasma phagocytophilum and Borrelia burgdorferi and to provide information from a group of cats with possible borreliosis as the cause of clinical manifestations of disease. All cases were evaluated at one clinic, medical records were evaluated, and sera from all cats were tested using one of two commercially available assays labeled for the use with dog sera (SNAP 4Dx or SNAP 4Dx Plus; IDEXX Laboratories, Westbrook, ME). Of the 159 cats evaluated, 42 cats (26.4%) had clinical signs consistent with A. phagocytophilum or B. burgdorferi infection and 117 cats (73.6%) were apparently healthy. Antibodies against B. burgdorferi or A. phagocytophilum were detected in sera of 18.2% and 6.3% of the 159 cats, respectively. Cats with clinical signs of disease were 4 times more likely to have antibodies against one or both agents than healthy cats (95% confidence interval [CI] 1.7928-8.9246; P = .0007), cats allowed outdoors were 5 times more likely to have antibodies against one or both agents than cats housed exclusively indoors (95% CI 2.0196-12.4497; P = .0005), and cats of owners who purchased acaricides were more likely (odds ratio = .3977) to have antibodies against one or both agents than cats of owners who did not purchase acaricides (95% CI .1659-.9534; P = .0387). The cats in the case series were believed to have B. burgdorferi infection as the most likely cause of illness based on serological testing, select clinical information, and apparent response to administration of doxycycline. The results suggest that both A. phagocytophilum and B. burgdorferi are associated with clinical illness in cats. Owners of cats allowed outdoors should be diligent in the use of acaricides.

Sensitivity and specificity levels of two rapid assays for antibodies to Anaplasma spp. in dogs

Canine anaplasmosis is a tick-borne disease of dogs that results following infection with Anaplasma phagocytophilum or Anaplasma platys. The SNAP 4Dx Plus test (IDEXX Laboratories) and the VetScan Canine Anaplasma Rapid test (Abaxis) are commercial in-house rapid tests for the detection of antibody to these 2 antigenically related Anaplasma species. We evaluated 2 tests using serum and whole blood samples obtained from reference laboratories and veterinary hospitals. Samples were obtained from regions of the country known to be habitats of the primary tick vectors. The A. phagocytophilum sample set comprised 236 dog sera from the northeastern and midwestern United States; the A. platys sample set comprised 179 sera from dogs living in the southwestern United States. An indirect immunofluorescent antibody (IFA) test and an A. platys species-specific ELISA were used as reference assays for the A. phagocytophilum and A. platys samples, respectively. The SNAP test demonstrated significantly higher sensitivity (84.7% for A. phagocytophilum and 83.1% for A. platys), compared to the VetScan test (39.0% for A. phagocytophilum and 57.6% for A. platys). The specificity of the SNAP test (95.8% for A. phagocytophilum and 99.2% for A. platys) was significantly greater than the VetScan test (85.6% for A. phagocytophilum and 82.5% for A. platys). In a separate clinic study, conducted within an A. phagocytophilum-endemic state (Minnesota) using 154 whole blood samples from client-owned dogs, the VetScan test was negative for 22 of 39 SNAP and IFA seropositive samples.

Serologic responses to peptides of Anaplasma phagocytophilum and Borrelia burgdorferi in dogs infested with wild-caught Ixodes scapularis

Anaplasma phagocytophilum and Borrelia burgdorferi are both transmitted by Ixodes spp. and are associated with clinical illness in some infected dogs. This study evaluated canine antibody responses to the A. phagocytophilum p44 peptides APH-1 and APH-4 as well as the B. burgdorferi C6 peptide before and after doxycycline treatment. A total of eight dogs were infested with wild-caught I. scapularis for 1 week. Blood was collected prior to tick attachment and from Days 3-77 to 218-302 with doxycycline treatment beginning on Day 218. Blood was assayed for A. phagocytophilum DNA by PCR assay. Sera was assessed for antibodies by immunofluorescent antibody (IFA) test and ELISA. Anaplasma phagocytophilum DNA was amplified from blood of all dogs by Day 7. Antibodies to APH-4 were detected in serum as early as 14days after tick exposure and six dogs had APH-4 antibodies detected 3-7 days before antibodies against APH-1. All dogs were seropositive for A. phagocytophilum from Days 218 to 302. Antibodies to B. burgdorferi were detected in 6/8 dogs beginning 21days after I. scapularis infestation. Among the five dogs that remained seropositive at Day 218, C6 antibody levels declined on average 81% within 84days of initiating treatment. The results suggest that the APH-4 peptide may be more useful than APH-1 for detecting antibodies earlier in the course of an A. phagocytophilum infection. After doxycycline administration, C6 antibody levels but not APH-1 or APH-4 antibody levels decreased, suggesting a treatment effect on C6 antibody production.

Analytical validation of a reference laboratory ELISA for the detection of feline leukemia virus p27 antigen

Feline leukemia virus (FeLV) is an oncogenic retrovirus of cats. Immunoassays for the p27 core protein of FeLV aid in the detection of FeLV infections. Commercial microtiter-plate ELISAs have rapid protocols and visual result interpretation, limiting their usefulness in high-throughput situations. The purpose of our study was to validate the PetChek FeLV 15 ELISA, which is designed for the reference laboratory, and incorporates sequential, orthogonal screening and confirmatory protocols. A cutoff for the screening assay was established with 100% accuracy using 309 feline samples (244 negative, 65 positive) defined by the combined results of FeLV PCR and an independent reference p27 antigen ELISA. Precision of the screening assay was measured using a panel of 3 samples (negative, low-positive, and high-positive). The intra-assay coefficient of variation (CV) was 3.9–7.9%; the inter-assay CV was 6.0–8.6%. For the confirmatory assay, the intra-assay CV was 3.0–4.7%, and the inter-assay CV was 7.4–9.7%. The analytical sensitivity for p27 antigen was 3.7 ng/mL for inactivated whole FeLV and 1.2 ng/mL for purified recombinant FeLV p27. Analytical specificity was demonstrated based on the absence of cross-reactivity to related retroviruses. No interference was observed for samples containing added bilirubin, hemoglobin, or lipids. Based on these results, the new high-throughput design of the PetChek FeLV 15 ELISA makes it suitable for use in reference laboratory settings and maintains overall analytical performance.

Evaluation of rapid diagnostic test kits for feline leukemia virus infection using samples from naturally infected cats

Objectives

Feline leukemia virus (FeLV) is a potentially life-threatening oncogenic retrovirus. The p27 viral core protein is produced by the virus in infected feline cells, is found in the cytoplasm in several blood cells and can be free in the serum and plasma. ELISA or particle-based immunoassay are commonly used to detect the presence of the p27 core protein in samples obtained from blood. The objective of this study was to compare the performance of several in-clinic tests: the SNAP Feline Triple Test (IDEXX Laboratories), the WITNESS FeLV-FIV Test (Zoetis) and the VetScan Feline FeLV/FIV Rapid Test (Abaxis).

Methods

The sample population (100 positive, 105 negative samples) consisted of serum and plasma samples submitted to IDEXX’s worldwide reference laboratory for feline retrovirus testing. Virus isolation and reverse transcriptase PCR results were not available and so samples were judged to be positive or negative based on the results of the ViraCHEK FeLV (Zoetis) microtiter plate assay.

Results

The percentage of samples positive and negative for FeLV p27 antigen using the three in-clinic tests compared with the ViraCHEK method were as follows: IDEXX Feline Triple (positive 98.0%, negative 100%); Zoetis WITNESS (positive 79.0%, negative 97.1%); Abaxis VetScan (positive 73.0%, negative 97.1%).

Conclusions and relevance

The SNAP Feline Triple Test demonstrated a high level of agreement for FeLV-positive and FeLV-negative samples when assessed in this model. Results of FeLV assays can vary among tests.

Point prevalence survey for tick-borne pathogens in military working dogs, shelter animals, and pet populations in northern Colombia

BACKGROUND

Based on the high tick-borne pathogen results from a 2011 surveillance study in three Colombian cities, an in-depth point prevalence survey was conducted to determine the seroprevalence of tick-borne pathogens at a specific point in time in 70 working dogs, 101 shelter dogs, and 47 client-owned dogs in Barranquilla, Colombia.

RESULTS

Of the 218 serum samples, 163 (74%) were positive for Ehrlichia canis and 116 (53%) for Anaplasma platys. Exposure to tick-borne pathogens was highest in shelter and working dogs where more than 90% of the samples were seropositive or positive on polymerase chain reaction for one or more organisms as compared to 51% in client-owned animals.

CONCLUSION

Surveillance for exposure to tick-borne pathogens provides vital information necessary to protect and conserve the health of local humans and animals, deployed military service members, and working dogs in various parts of the world. This study and resultant data demonstrate the value of following a broad-based surveillance study with a more specific, focused analysis in an area of concern. This area?s high levels of exposure warrant emphasis by medical planners and advisors on precautionary measures for military dogs, Special Operations Forces personnel, and the local public.

Evidence of Anaplasma phagocytophilum and Borrelia burgdorferi infection in cats after exposure to wild-caught adult Ixodes scapularis

Cats are infected by Anaplasma phagocytophilum and Borrelia burgdorferi when exposed to infected Ixodes scapularis (black-legged ticks). The purpose of our study was to allow wild-caught I. scapularis to feed on healthy research cats (n = 4) and temporally evaluate for A. phagocytophilum DNA in blood by a polymerase chain reaction (PCR) assay as well as for antibody responses to the B. burgdorferi C6 peptide, to the A. phagocytophilum P44 peptide, and to a novel A. phagocytophilum peptide (P44-4). Prior to I. scapularis infestation, all cats were negative for antibodies against both organisms based on a kit optimized for dog serum, and negative for A. phagocytophilum DNA in blood using a conventional PCR assay. Using the pre-infestation samples, an enzyme-linked immunosorbent assay for detecting antibodies against the P44-4 peptide was optimized. Cats were infested with wild-caught I. scapularis for 7 days. Genomic DNA of A. phagocytophilum was amplified from the blood before antibodies were detected in all 4 cats. Antibodies against the C6 peptide, P44 peptide, and P44-4 peptide were detected in the sera of all 4 cats. Antibodies against P44-4 were detected prior to those against P44 in 3 out of 4 cats. The results suggest that a PCR assay should be considered in acutely ill cats with suspected anaplasmosis that are seronegative.

Serological and molecular analysis of feline vector-borne anaplasmosis and ehrlichiosis using species-specific peptides and PCR

Background

With the exception of Bartonella spp. or Cytauxzoon felis, feline vector-borne pathogens (FVBP) have been less frequently studied in North America and are generally under-appreciated as a clinical entity in cats, as compared to dogs or people. This study investigated selected FVBP seroreactivity and PCR prevalence in cats using archived samples.

Methods

Feline blood samples submitted to the Vector Borne Diseases Diagnostic Laboratory (VBDDL) at North Carolina State University College of Veterinary Medicine (NCSU-CVM) between 2008 and 2013 were tested using serological assays and PCR. An experimental SNAP® Multi-Analyte Assay (SNAP® M-A) (IDEXX Laboratories, Inc. Westbrook, Maine, USA) was used to screen all sera for antibodies to Anaplasma and Ehrlichia genus peptides and A.phagocytophilum, A.platys, B.burgdorferi, E.canis, E.chaffeensis, and E.ewingii species-specific peptides. PCR assays were used to amplify Anaplasma or Ehrlichia DNA from extracted ethylenediaminetetraacetic acid (EDTA)-anti-coagulated blood samples. Amplicons were sequenced to identify species.

Results

Overall, 7.8 % (56/715) of cats were FVBP seroreactive and 3.2 % (13/406) contained Anaplasma or Ehrlichia DNA. Serologically, B.burgdorferi (5.5 %) was the most prevalent FVBP followed by A.phagocytophilum (1.8 %). Ehrlichia spp. antibodies were found in 0.14 % (12/715) of cats with species-specific seroreactivity to E.canis (n = 5), E.ewingii (n = 2) and E.chaffeensis (n = 1). Of seropositive cats, 16 % (9/56) were exposed to more than one FVBP, all of which were exposed to B.burgdorferi and either A.phagocytophilum (n = 7) or E.ewingii (n = 2). Based upon PCR and DNA sequencing, 4, 3, 3, 2, and 1 cat were infected with A.phagocytophilum, A.platys, E. ewingii, E. chaffeensis and E.canis, respectively.

Conclusions

Cats are exposed to and can be infected with vector-borne pathogens that commonly infect dogs and humans. To our knowledge, this study provides the first evidence for E.chaffeensis and E.ewingii infection in naturally-exposed cats in North America. Results from this study support the need for regional, serological and molecular FVBP prevalence studies, the need to further optimize serodiagnostic and PCR testing for cats, and the need for prospective studies to better characterize clinicopathological disease manifestations in cats infected with FVBP.

Persistent Ehrlichia ewingii infection in dogs after natural tick infestation

Background

Ehrlichia ewingii, which causes disease in dogs and people, is the most common Ehrlichia spp. infecting dogs in the United States, but little is known about how long E. ewingii infection persists in dogs.

Hypothesis/Objectives

To evaluate the persistence of natural infection with E. ewingii in dogs.

Animals

Four Class A Beagles; no previous exposure to ticks or tick‐borne infectious agents.

Methods

Dogs were exposed to ticks by weekly walks through tick habitat in north central Oklahoma; dogs positive for infection with Ehrlichia spp. by sequence‐confirmed PCR and peptide‐specific serology were evaluated for 733 days (D). Whole blood was collected once weekly for PCR, and serum was collected once monthly for detection of antibodies to Ehrlichia canis (peptide p16), Ehrlichia chaffeensis (indirect fluorescence antibody [IFA] and variable‐length PCR target [VLPT]), and E. ewingii (peptide p28).

Results

All dogs (4/4) became infected with Ehrlichia spp. as evidenced by seroconversion on IFA to E. chaffeensis (4/4); PCR detection of E. ewingii (4/4) and E. chaffeensis (2/4) DNA using both nested and real‐time assays; and presence of specific antibodies to E. ewingii (4/4) and E. chaffeensis (2/4). Infection with E. chaffeensis was not detected after D55. Intermittent E. ewingii rickettsemia persisted in 3 of 4 dogs for as long as 733 days.

Conclusions and Clinical Importance

Our data demonstrate that dogs infected with E. ewingii from tick feeding are capable of maintaining infection with this pathogen long‐term, and may serve as a reservoir host for the maintenance of E. ewingii in nature.

Serosurvey of tick-borne pathogens in dogs from urban and rural areas from Parana State, Brazil

Considering the zoonotic potential of tick-borne disease (TBD) agents and the fact that dogs may act as sentinels for human infection, the aim of the present study was to determine the seroprevalence of TBD agents and risk factors for exposure in two different canine populations from Parana State, Southern Brazil. A total of 138 dog serum samples from urban (UA) (n=68) and rural (RA) (n=70) areas were tested with commercial ELISA rapid test for Anaplasma phagocytophilum, Ehrlichia canis and Borrelia burgdorferi antibodies and indirect immunofluorescence assay (IFAT) for Babesia vogeli. An overall of 92∕138 (66.7%) dogs, being 62∕68 (91.2%) from UA and 30∕70 (42.9%) from RA, were seropositive for at least one TBD agent. From the total number of dogs, sixty-two were positive for E. canis (44.9%), 19 (13.8%) for A. phagocytophilum, and 64 (46.4%) for B. vogeli. Anti-B. burgdorferi antibodies were not detected. Dogs from UA showed a higher percentage of tick infestation (p = 0.0135) and were highly associated with seropositivity to E. canis (p = 0.000005), A. phagocytophilum (p = 0.0001), and B. vogeli (p = 0.0012). In summary, the findings indicate that dogs from urban areas present higher potential risk exposure to TBD pathogens than those from rural areas.

A serological survey of tick-borne pathogens in dogs in North America and the Caribbean as assessed by Anaplasma phagocytophilum, A. platys, Ehrlichia canis, E. chaffeensis, E. ewingii, and Borrelia burgdorferi species-specific peptides

Introduction

Tick-borne pathogens cause a spectrum of disease manifestations in both dogs and humans. Recognizing regional and temporal shifts in exposure are important as tick distributions change. To better delineate regional exposure to canine tick-borne pathogens, an expanded set of species-specific peptides were used to detect Anaplasma phagocytophilum (Aph), Anaplasma platys (Apl), Ehrlichia canis (Ec), Ehrlichia chaffeensis (Ech), Ehrlichia ewingii (Eew), and Borrelia burgdorferi (Bb) antibodies in canine serum.

Methods

Archived canine serum samples (n=6,582) collected during 2008–2010 and in 2012 from the US, Canada, and the Caribbean were retrospectively screened for antibodies against Ehrlichia and Anaplasma species-specific peptides. Overall, regional and temporal seroprevalence rates were determined.

Results

Overall Bb and Eew were the most seroprevalent pathogens. During 2008–2010, seroprevalence rates increased overall for Aph and Ech, and regionally, Bb and Aph seroprevalence rates increased in the South. Canada had unexpectedly high seroprevalence rates for Ec and Apl. The most common co-exposures were Eew+Ech, followed by Aph+Bb and Eew+Bb.

Conclusions

This study demonstrated significant shifts in canine vector-borne disease seroprevalence rates. The use of specific peptides facilitated improved geographic delineation of tick-borne pathogen distributions among dogs, which may enhance epidemiological surveillance of vector-borne pathogens shared by dogs and humans.

Experimental Dirofilaria immitis infection in dogs: effects of doxycycline and Advantage Multi® administration on immature adult parasites

To better understand the efficacy of doxycycline and 10% imidacloprid+2.5% moxidectin (Advantage Multi(®); Bayer Animal Health, Shawnee Mission, Kansas) on immature adult Dirofilaria immitis parasites and the results of antigen tests, 12 healthy, randomly selected dogs were experimentally infected with D. immitis and monitored for 407 days. Two dogs in each of three subgroups of four dogs were each infected with six (total of 6 dogs) or 12 (total of 6 dogs) D. immitis infective third-stage larvae (L3) obtained from infected mosquitoes. Doxycycline (10mg/kg per os twice daily×30 days) and 10% imidacloprid+2.5% moxidectin (1ml/kg by topical application every 30 days) treatment was initiated at 105 (Group A) and 149 (Group B) days post infection (PI) in two groups. One subgroup of two dogs given 6 L3 and one subgroup of two dogs given 12 L3 remained as untreated controls (GroupC). Serum obtained regularly throughout the study was evaluated by ELISA (PetChek(®) Heartworm-PF Antigen Test, IDEXX Laboratories, Inc.) for D. immitis adult circulating antigens. Six of the eight dogs in the treated groups had detectable antigenemia starting between 148 and 240 days post infection, but antigen was not detected in any treated dog at the end of the study. In the control subgroups, the dogs that received 6 L3 had no detectable antigen while the two dogs that received 12 L3 had detectable antigen beginning on Day 180 that persisted until the end of the study. None of the infected dogs had evidence of circulating microfilariae. At necropsy, no heartworms were recovered from the treated dogs, but all dogs in the untreated group had viable adult heartworms. These results indicate that early immature adult worms (3.5 and 5 months of age) of D. immitis were susceptible to a combined treatment regimen of doxycycline and 10% imidacloprid+2.5% moxidectin.

Development of antibodies to and PCR detection of Ehrlichia spp. in dogs following natural tick exposure

Dogs exposed to ticks in the southern US may become infected with multiple species of Ehrlichia. To better define infection risk, blood samples collected from 10 dogs infested with ticks via a natural infestation model were evaluated by blood smear examination, PCR, patient-side ELISAs (SNAP® 4Dx® and SNAP® 4Dx® Plus), IFA, and peptide based ELISA for evidence of infection with Ehrlichia canis, E. chaffeensis, and/or E. ewingii. Although morulae were rarely identified in blood smears, every dog (10/10) became infected with Ehrlichia spp. as evidenced by nested PCR detection of E. chaffeensis (7/10) and E. ewingii DNA (10/10); real-time PCR detection of E. chaffeensis (0/10) and E. ewingii (9/10); seroconversion on two different patient-side ELISAs (4/10 or 10/10); seroconversion on IFA to E. canis (10/10, maximum inverse titer=128-4096, GMTMAX=548.7) and E. chaffeensis (10/10, maximum inverse titer=1024-32,768, GMTMAX=4096); and seroconversion on peptide specific ELISA to E. chaffeensis VLPT (7/10) and E. ewingii p28 (9/10). Rickettsemia with E. chaffeensis and E. ewingii, as determined by nested PCR, persisted in dogs for an average of 3.2 or 30.5 days, respectively. Ehrlichia canis was not detected in any dog by any method, and no dogs developed signs of clinical disease. Our data suggest that in areas where ticks are common, dogs are at high risk of infection with Ehrlichia spp., particularly E. ewingii and E. chaffeensis, and can serve as a sentinel for monitoring for the presence of these zoonotic pathogens.

Canine infection with Dirofilaria immitis, Borrelia burgdorferi, Anaplasma spp., and Ehrlichia spp. in the United States, 2010-2012

Background

The geographic distribution of canine infection with vector-borne disease agents in the United States appears to be expanding.

Methods

To provide an updated assessment of geographic trends in canine infection with Dirofilaria immitis, Borrelia burgdorferi, Ehrlichia spp., and Anaplasma spp., we evaluated results from an average of 3,588,477 dogs tested annually by veterinarians throughout the United States from 2010 – 2012.

Results

As in an earlier summary report, the percent positive test results varied by agent and region, with antigen of D. immitis and antibody to Ehrlichia spp. most commonly identified in the Southeast (2.9% and 3.2%, respectively) and antibody to both B. burgdorferi and Anaplasma spp. most commonly identified in the Northeast (13.3% and 7.1%, respectively) and upper Midwest (4.4% and 3.9%, respectively). Percent positive test results for D. immitis antigen were lower in every region considered, including in the Southeast, than previously reported. Percent positive test results for antibodies to B. burgdorferi and Ehrlichia spp. were higher nationally than previously reported, and, for antibodies to Anaplasma spp., were higher in the Northeast but lower in the Midwest and West, than in the initial report. Annual reports of human cases of Lyme disease, ehrlichiosis, and anaplasmosis were associated with percent positive canine test results by state for each respective tick-borne disease agent (R² = 0.701, 0.457, and 0.314, respectively). Within endemic areas, percent positive test results for all three tick-borne agents demonstrated evidence of geographic expansion.

Conclusions

Continued national monitoring of canine test results for vector-borne zoonotic agents is an important tool for accurately mapping the geographic distribution of these agents, and greatly aids our understanding of the veterinary and public health threats they pose.

Vaccine-associated Leptospira antibodies in client-owned dogs

Background

Long‐term microscopic agglutination test (MAT) results after vaccination with 4‐serovar Leptospira vaccines are not available for all vaccines used in client‐owned dogs.

Hypothesis/Objectives

To determine antibody responses of client‐owned dogs given 1 of 4 commercially available Leptospira vaccines.

Animals

Healthy client‐owned dogs (n = 32) with no history of Leptospira vaccination for at least the previous year.

Methods

Dogs were given 1 of 4 Leptospira vaccines on week 0 and then approximately on week 3 and week 52. Sera were collected before vaccine administration on week 0 and then within 3 days of week 3, within 2 days of week 4, and approximately on weeks 7, 15, 29, 52, and 56. Antibody titers against Leptospira serovars bratislava, canicola, grippotyphosa, hardjo, icterohemorrhagiae, and pomona and were determined by MAT.

Results

When compared among vaccines, MAT results varied in maximal titers, the serovars inducing maximal titers, and the time required to reach maximal titers. Each vaccine induced at least some MAT titers ≥1 : 800. Most dogs were negative for antibodies against all serovars 1 year after vaccination, and anamnestic responses were variable.

Conclusions and Clinical Importance

Dogs vaccinated with Leptospira vaccines have variable MAT titers over time, and antibodies should not be used to predict resistance to Leptospira infection. MAT titers ≥1 : 800 can develop after Leptospira spp. vaccination, which can complicate the clinical diagnosis of leptospirosis.

Serological survey of Ehrlichia species in dogs, horses and humans: zoonotic scenery in a rural settlement from southern Brazil

The aims of this study were to determine the seroprevalence of Ehrlichia spp. and risk factors for exposure in a restricted population of dogs, horses, and humans highly exposed to tick bites in a Brazilian rural settlement using a commercial ELISA rapid test and two indirect immunofluorescent assays (IFA) with E. canis and E. chaffeensis crude antigens. Serum samples from 132 dogs, 16 horses and 100 humans were used. Fifty-six out of 132 (42.4%) dogs were seropositive for E. canis. Dogs > one year were more likely to be seropositive for E. canis than dogs ≤ one year (p = 0.0051). Ten/16 (62.5%) and 8/16 (50%) horses were seropositive by the commercial ELISA and IFA, respectively. Five out of 100 (5%) humans were seropositive for E. canis and E. chaffeensis. Rhipicephalus sanguineus (n = 291, 97.98%) on dogs and Amblyomma cajennense (n = 25, 96.15%) on horses were the most common ticks found. In conclusion, anti-Ehrlichia spp. antibodies were found in horses; however, the lack of a molecular characterization precludes any conclusion regarding the agent involved. Additionally, the higher seroprevalence of E. canis in dogs and the evidence of anti-Ehrlichia spp. antibodies in humans suggest that human cases of ehrlichiosis in Brazil might be caused by E. canis, or other closely related species.