Wild mammals as sylvatic reservoirs of Trypanosoma cruzi.  Trypanosoma cruzi is the etiological agent for Chagas' disease, being vectored by members of the blood-feeding reduviid family of arthropods. The insect's habit of feeding upon the face, particularly around the mouth, has earned these insects the common name "Kissing Bugs". T. cruzi currently infects approximately 20 million people, and The World Health Organization currently lists Chagas' disease in its list of top ten tropical diseases for increased research. They specifically suggest that new research targeting sylvatic vector and reservoir populations would yield the greatest benefits to scientific and health. While commonly associated with the Lower Americas, T. cruzi and its vectors are widely distributed across southern North America. Numerous wild and domestic mammals serve as sylvatic reservoirs for the parasite, with prevalence rates reaching 60% in some regions. Although opportunities for human infection must certainly occur, there have been only limited descriptions of autochthonous infections in man, despite evidence that primate species are susceptible to regional parasite strains. Although one reason for the low prevalence rate among the human population is believed to involve differences in vector feeding behavior and quality of housing, no data has been offered to support the theory. We propose to experimentally explore the behavior of the regional vector species, Triatoma sanguisuga, and compare it to other vector species associated with transmission in T. cruzi in humans. We will also continue to conduct surveys of sylvatic reservoir hosts to establish relative prevalence in raccoons and opossums. In addition, experimental infections will be carried out in mice to measure the virulence and transmission of regional isolates and compare them to those in Latin America.  NSF-REU students would be involved in the design and conduction of feeding trials, maintenance of experimental T. sanguisuga cultures, immunological assays, data analysis, and presentation/publication activities.