Epidemiology of Vector-Borne Pathogens Among U.S. Government Working Dogs

Abstract

Surveillance of U.S. domestic dogs for exposure to vector-borne pathogens can identify regions of transmission that are relevant for human and animal health. Working dogs with high levels of outdoor exposure may be sensitive indicators of local risk, owing to increased contact with vectors. We randomly selected 476 high-value government working dogs from 40 states to determine the prevalence of infection with Dirofilaria immitis and Rickettsia spp., and exposure to Ehrlichia spp., Anaplasma spp., and Borrelia burgdorferi, and identify risk factors for positivity. Additionally, we tested 100 of these dogs from Texas for Leishmania spp. where sand fly vectors occur. Previously published Trypanosoma cruzi infection data on these dogs were used to identify coinfection or co-exposures. Infection prevalence was 0.84% for D. immitis, and all dogs were negative for Rickettsia spp. DNA. Seroprevalence of each pathogen was: B. burgdorferi 0.84%, Ehrlichia spp. 1.3%, Anaplasma spp. 1.5%, Leishmania spp. 2.0%, and T. cruzi 12.2%. Coinfection or co-exposure took place in four (0.84%) dogs. In bivariable analysis, we found that D. immitis-positive and Ehrlichia-seropositive dogs were significantly older than negative dogs ( p < 0.05). Furthermore, seroprevalence of Anaplasma spp. was significantly higher among dogs in the Northeast United States relative to other areas of the country (4.7% vs. £ 1.4%; p = 0.041). Although autochthonous Leishmania infections have been described in the United States, the cases reported herein may represent imported Leishmania infection. Most federal working dogs are bred in Europe, where the parasite is endemic and congenitally transmitted. Serological cross-reaction between T. cruzi and Leishmania spp. complicates diagnosis. In this study, the use of multiple testing strategies in a comparative complementary manner provided evidence for these dogs' true exposures. Comprehensive surveillance for vector-borne pathogens in dogs can improve clinician awareness and target prevention and treatment in a One Health manner.

Tick-Borne Pathogens, Babesia spp. and Borrelia burgdorferi s.l., in Sled and Companion Dogs from Central and North-Eastern Europe

“…This is actually evidence for the good quality of health care that sled dogs receive these days. Interestingly, in military working dogs in the USA, seroprevalence of anti- Borrelia burgdorferi antibodies was much lower (0.9%, [ 36 ]) than in the general population (1.2–16%, [ 37 , 38 ]).…”

“…Our study was based on the molecular detection of microorganisms’ DNA in canine blood samples. The vast majority of published studies, however, are based on the detection of antibodies against TBPs, and hence reflect overall exposure risk, rather than currently present infections [ 36 , 37 , 38 ]. Serological tests are widely used for the diagnostics of Borrelia burgdorferi infection in dogs [ 37 , 38 , 39 ].…”

Validation of a multiplex microsphere immunoassay for detection ofTrypanosoma cruziantibodies in dogs

“…This included the samples which were categorized as clearly seropositive (n = 27) and clearly seronegative (n = 33) by the prior serological tests in the original study. Validating the assay with these samples of congruent serostatus was done because there remains uncertainty in the true infection status for animals that have discordant test results, and there is yet to be an accepted gold standard serologic test for T. cruzi exposure in human or veterinary medicine 8, 10, 15, 16 . Once cutoff criteria for the MIA were established with this sample set, we then used the full sample set which includes dogs sampled at multiple time points to monitor changes in serostatus over time.…”

Validation of a multiplex microsphere immunoassay for detection of antibodies to Trypanosoma cruzi in dogs

“…Validating the assay with these samples of congruent serostatus was done because there remains uncertainty about the true infection status for animals that have discordant test results, and there is no accepted gold standard serologic test for T. cruzi exposure in human or veterinary medicine. 8,10,15,16 Once we had established cutoff criteria for the MIA with this smaller validation sample set, we then used the full sample set from the 37 dogs sampled at multiple times to monitor changes in serostatus over time.…”