Little is known about human-environment relations that increase exposure to zoonotic diseases, in spite of associations between deforestation and emergence of these pathogens. Trypanosoma cruzi, the cause of Chagas disease in humans, is a zoonosis that cycles between triatomine vectors and a wide range of wild and domestic mammal hosts, including domestic dogs. Domestic dogs can be considered sentinels for human infection risk due to their close association with humans. In this study, we evaluate ecological, socioeconomic, cultural, and intrinsic (host-related) factors related to T. cruzi exposure in domestic dogs in villages of central Panama surrounded by different degrees of deforestation (from approximately 65% forest cover to completely deforested). We hypothesize that community-level T. cruzi exposure in dogs will be higher in villages with intermediate levels of deforestation, be associated with the dog’s household proximity to Attalea butyracea palms, and be related to the dog owner's socioeconomic status. Dogs (N=181) were sampled from three communities across a temporal and spatial deforestation gradient, from most deforested to least: Pueblo Nuevo (PN), Cañazas (CA), and Bajo Bonito (BB). Physical examination, blood, ectoparasite, and fecal collection were performed on each dog, and laboratory analyses were performed to evaluate dog hematological values and exposure to T. cruzi. We also evaluated individual household and yard characteristics, peridomestic vegetation, and geographical features (forest cover, land use type, elevation, slope, aspect), and interviewed dog owners regarding socioeconomic status and other factors (e.g. behavior) relating to potential exposure of humans and dogs to T. cruzi.
Results/Conclusions
Community was found to be a significant determinant of T. cruzi exposure (p<0.01, χ2). Preliminary results show that dogs in the most deforested areas (PN) had a significantly lower different exposure to T. cruzi than the highly fragmented (CA) and relatively intact forest areas (BB) (p=0.005 and p=0.014 respectively, χ2). Intrinsic factors such as age, ectoparasite co-infection, body condition score, or hematology variables were not significantly associated with T. cruzi exposure. We also discuss study results evaluating relationships between coarse and fine-grained landscape features, socioeconomic, and cultural factors relating to the risk of T. cruzi transmission in domestic dogs as zoonotic disease sentinels.