Chagas disease ecology in Trinidad: Trypanosoma cruzi infection status and bloodmeal analysis of triatomine bugs on an island considered free of vector-borne transmission

Abstract

Background: Triatomine bugs, the vectors of Chagas disease, are found throughout several islands in the Caribbean (Petana, 1978), however little is known about the disease in the region despite their presence. Trinidad is a key island of interest for possible Chagas transmission in the Caribbean due to its proximity to highly endemic Venezuela, as well as the confirmed presence of Chagas disease vectors and its causative parasite, Trypanosoma cruzi, on the island (Petana, 1978; Fistein, 1966). This research aims to explore the ecology of Chagas disease in Trinidad through an investigation of triatomine habitat, T. cruzi infection status, T. rangeli (a common co-infector (Peterson et al., 2016)) infection status, and bloodmeal source in order to determine if the infected vector is making contact with humans (Eakes, May 2016). Method: Triatomine bugs were collected across the island of Trinidad using mouse-baited “Noireau traps” (Noireau et al., 2002) and collection cups given to people living near sample sites. Sampling site selection began with a more broad survey across the island of potential vector habitats, such as areas near potential mammalian host nests and near areas of human activity, but was narrowed to strictly sites near human residence, as those areas had the greatest yield. Collected bugs were analyzed in lab for the presence of T. cruzi DNA, T. rangeli DNA, and last mammalian bloodmeal source. Using a Chi-Square Test of Independence, we investigated an association between infection status and 1.) triatomine sex and 2.) bloodmeal source. Results: In total, 55 triatomine bugs were collected. All bugs were collected in one of five locations, with 46 (83.6%) coming from one location, Coalmine. All successful collection sites were forested areas near the northern and central range mountains, and all bugs were collected in and around human homes. 46 (83.6%) of the bugs were positive for T. cruzi, and of these, 20 contained human bloodmeals. We found a significant association between female bugs and positive infection status of bugs from Coalmine (p=1.397e-11).Conclusion: This study suggests that Chagas disease is a health concern in Trinidad, as there is the potential for T. cruzi transmission to humans. Much is still unknown about the habitats and seasonal behavior of the triatomine vectors in Trinidad, however this study sets the stage for many promising directions of future research on Chagas disease vector ecology in Trinidad.