When vectors bloodfeed from dozens of different wild or domestic hosts, there are many opportunities to acquire or deliver an infection; these complex transmission cycles challenge vector-borne disease management. Increasingly, the use of genetic tools allows for source-tracking of infections and the identification of key host or vector taxa that are responsible for spillover risk to humans. Despite over 100 years of research on Trypanosoma cruzi, this parasite continues to cause significant morbidity and mortality (Chagas disease) in human and animal populations across the Americas. Parasite transmission networks are vastly different across geographic regions, ranging from domestic infestations of triatomine vectors with high human contact to sylvatic transmission among wildlife with only occasional spillover to humans. In a one health approach, our goal is to identify the key ecological drivers of Chagas disease in the southern US, where there is increasing recognition of locally-acquired disease. In addition to targeted field studies of naturally-infected dogs and wildlife, we use citizen science to empower the public with disease prevention information while accepting citizen-collected triatomines for analysis.
Results/Conclusions
Molecular analysis of over 4500 triatomines across 20 southern states revealed >55% T. cruzi infection. In our comparative wildlife evaluations in Texas, raccoons (Procyon lotor) have emerged as a key, infectious reservoir with over 70% of raccoons (n=99) from central Texas having T. cruzi-infected heart tissue. In contrast, 0-14% of feral hogs, bats, bobcats, coyotes, fox, and rodents were infected (n=844). We have studied T. cruzi-infected shelter dogs, government working dogs, and pet dogs to link epidemiology with pathology, and found that variation in parasite genetics is linked to clinical outcome. Infection with parasite discrete typing unit TcIV is more likely to result in asymptomatic infections relative to TcI which is more commonly associated with myocarditis. Through the use of next generation amplicon deep sequencing, we are conducting bloodmeal analysis to describe the network of hosts fed upon by individual insects, including wildlife, domestic animals, and humans. Together, these studies highlight how parasite and host genetics reveal important interactions in the ecology of Chagas disease.