American trypanosomiasis in dogs from an urban and rural area of Yucatan, Mexico.

American trypanosomiasis in dogs is reported from South of the United States to Argentina and Chile. It is transmitted through the contact of dogs with reduviid insects when they feed; reduviid insects are well established in the southern state of Yucatan, Mexico. However, there are no reports available about trypanosomiasis prevalence in dogs of urban and rural areas. A cross-sectional study was performed in 345 stray dogs, 102 from a rural community of Yucatan (Tunkas) and 243 from Merida, capital city of the Yucatan state. Serum samples were obtained for detection of immunoglobulin G antibodies against Trypanosoma cruzi by indirect immunofluorescence assay and Western blot. DNA was extracted from whole blood of urban dogs for polymerase chain reaction (PCR) assay. Prevalence was determined and the risk to become infected in both urban and rural dogs was evaluated using a 2 x 2 contingency table. In addition to the effect of body condition score (BCS), the age and sex of dogs were also evaluated to determine the risk of infection. Antibody prevalence against T. cruzi in rural areas was 9.8%, whereas in urban dogs was 14.4%. When PCR results were included, prevalence in dogs from the urban area increased to 17.3%. PCR allowed the detection of active asymptomatic acute-phase disease. The risk to become infected was not different between urban and rural areas, suggesting that the vector is well adapted both to rural areas and urban sprawling. Dogs with poor BCS tended to have a higher probability of seroreactivity to T. cruzi proteins than dogs with regular or good BCS (p = 0.05).