Canine trypanosomiasis in an endemic Costa Rican community: Demonstration of the active infection cycle.

A cross-sectional study was conducted to determine the prevalence of canine trypanosomiasis in an endemic community of Costa Rica. The indirect hemagglutination and indirect immunofluorescence assay yielded positive results in 6.4% (20/314) of canine samples analyzed; polymerase chain reaction (PCR) and light microscopy yielded positive results in one dog. Subsequently, a longitudinal study was carried out with 55 negative T. cruzi canines in the cross-sectional study. These dogs were divided into two groups: Group 1, which consisted of 25 individuals that lived in dwellings where triatomines were found in their homes; and Group 2, which consisted of 30 dogs that lived in dwellings where triatomines were not found during the previous study in their homes. Seroconversion occurred in six dogs (10.9%) in Group 1 in the first months of the year (dry season); these dogs remained seropositive until the end of the study. Only one of the six seropositive canines was also found positive once in T. cruzi PCR. The analysis of the amplified T. cruzi sequences of dogs and triatomines showed that all of them belonged to the TcI lineage. It is recommended that residents be made aware of the need to eliminate vectors in their homes and their surroundings.

Serological detection of antibodies to Anaplasma spp., Borrelia burgdorferi sensu lato and Ehrlichia canis and of Dirofilaria immitis antigen in dogs from Costa Rica.

In a study in Costa Rica 314 serum samples from dogs throughout all seven provinces were tested using a commercial kit for the detection of circulating antibodies against Anaplasma spp., Borrelia burgdorferi sensu lato and Ehrlichia canis, and of circulating antigen of Dirofilaria immitis. A total of 6.4% (20/314) and 38.2% (120/314) were positive for Anaplasma spp. (An) and E. canis (Ec) antibodies. Overall, 8.0% (25/314) were positive for D. immitis (Di) antigen. One single dog reacted positive with B. burgdorferi s.l. (Bb) antigen (0.3%, 1/314). E. canis positive dogs were detected in all provinces (highest percentages in Guanacaste, Puntarenas [both significantly different compared to the overall] and Limón). Guanacaste and Puntarenas also showed the highest prevalences of Anaplasma spp. (both significantly different compared to the overall). The highest prevalence of D. immitis was detected in Puntarenas (significantly different compared to the overall). Double pathogen exposure (Ec plus An; Ec plus Di; Ec plus Bb) were recorded in 8.9% (28/314). Two dogs showed a triple pathogen exposure (0.6%, 2/314; An, Ec and Di). There was a significant difference between male (11.5%, 18/156) and female (4.4%, 7/158) animals for D. immitis positive results. There was also a significant difference between breed and no breed dogs regarding the characteristics of a general positive test, as well as seropositivity to the single pathogens of Anaplasma spp., E. canis and D. immitis. Finally there was a significant difference in the presence of clinical signs again regarding the characteristics of a general positive test, as well as seropositivity to Anaplasma spp., E. canis and D. immitis. Practitioners in Costa Rica should be aware of the canine vector-borne diseases mentioned as dogs are at risk of becoming infected. Concerning the positive B. burgdorferi s.l. dog, an autochthonous occurrence cannot be confirmed due to a history of adoption and an unusual tattoo number. Veterinary advice to protect dogs and limit transmission of vector-borne pathogens, also to humans, by using prophylactic measures is strongly recommended.

Characterization of Anaplasma spp. infection in dogs from Costa Rica.

A cross-sectional study combining serological and molecular techniques for detecting selected Anaplasma species was conducted between 2011 and 2012 in dogs and ticks sampled in all provinces of Costa Rica. Global Anaplasma spp. seroprevalence was 2.7% (11/408) by indirect immunofluorescence assay. The 16S rRNA PCR confirmed active A. phagocytophilum infection only in one dog (0.3%, 1/374); however, the same sample was negative to groEL PCR. Out of 122 Rhipicephalus sanguineus s.l. ticks analyzed, one (0.8%) was found positive to A. phagocytophilum 16S rRNA PCR but negative when tested by groEL PCR; this tick was collected from a seronegative and PCR negative dog. Both 16S rRNA sequences were 100% (510/510bp) identical to A. phagocytophilum strains isolated in different countries from different hosts. The presence of A. platys was established in four dogs (1%, 4/374) by both 16SrRNA and groEL PCR. Ticks collected from the same dogs tested negative by PCR. The 16S rRNA sequences were 100% identical to the corresponding sequences of A. platys strains isolated from dogs in Croatia and Brazil, however groEL sequences showed variable similarity levels (99-100%) with different strains of A. platys isolated in Chile, Japan and Thailand, pointing out the possible presence of different variants in Central America. Collectively data indicate low prevalence of A. phagocytophilum and A. platys in dogs from Costa Rica. Furthermore, infections seem to occur without clinical signs but with some hematological changes, and seem to resolve without treatment.