Modeling Domestic Guinea Pigs and Trypanosoma cruzi Persistence in Arequipa, Peru

Abstract

Chagas disease is a vector-borne disease caused by the parasite, Trypanosoma cruzi. The disease is endemic in rural Latin America, affecting nearly 8 million people. While historically the disease has been associated with the rural poor, Chagas is now being detected in urban areas. In Peru, guinea pigs represent an important cultural animal and are readily found in the domestic sphere. Guinea pigs are potentially an important Chagas animal reservoir as they can harbor the parasite and are prevalent in communities. In the growing peri-urban community of Arequipa, there is a constant, local demand for guinea pigs and these animals are involved in an active migration network. With the habitual turnover of guinea pigs both to and within the city, there is the potential for spread of infected animals, which can contribute to community and household parasite transmission. Through a series of studies we investigate the contribution of guinea pigs as an animal reservoir in the transmission of T. cruzi using the Ross MacDonald mathematical framework. While previous models have investigated the role of dogs, cats and chickens, there is limited modeling analyses on the impact of domestic guinea pigs on T. cruzi transmission. In this paper, we found that guinea pigs are not a persistence source of infection in the average household. With migration, however, our model shows that guinea pigs can contribute to parasite persistence in vectors. Furthermore, a household subpopulation within a community can self-sustain the parasite in both vector and guinea pig populations if there is a sufficiently high vector-host ratio.