Abstract

Leishmaniasis and trypanosomiasis are important zoonotic diseases in many parts of South America. Domestic dogs and crab-eating foxes (Cerdocyon thous) are considered significant reservoirs for pathogenic Leishmania spp. We sampled 124 dogs and 8 wild canids (5 pampas foxes [Pseudalopex gymnocercus] and 3 crab-eating foxes) and tested them for antibodies to Leishmania donovani and Trypanosoma cruzi using indirect immunofluorescence assays. Forty dogs lived in towns on the eastern border of Madidi National Park, part of the Amazon basin in northwestern Bolivia. The remaining dogs and all of the wild canids were from the Chaco, a tropical dry forest in southeastern Bolivia. Seven dogs (17.5%) from the Madidi area had positive titers (≥1:16); four of these dogs were clearly positive for T. cruzi. The other three dogs were positive for both T. cruzi and L. donovani, but because of cross-reactivity it could not be determined which organism was predominant. In the Chaco, 44 of 84 (52%) of dogs had positive results. Sera from 34 of these dogs were clearly reacting to T. cruzi; the remaining 10 reacted similarly to both organisms. Two of the Madidi dogs, and 36 of the Chaco dogs, had high titers (≥256). One crab-eating fox was positive; this animal had equally low positive titers (1:32) to both organisms. In these two areas of Bolivia, trypanosomiasis may be more common than leishmaniasis in the domestic dog population, and dogs in the Chaco may have much greater exposure than dogs in more humid forests.