The expansion of human activity into tropical forests acts to increase human-wildlife contact (Aguirrea and Taborb 2008, Roque and Jansen 2014) and thus potential emergence of infectious zoonotic disease into human communities from wildlife reservoirs. While the relationship between zoonotic disease and ecosystems is complicated, we know that it is rooted by the interactions between hosts, vectors, and pathogens (Blaustein et al. 2012). In this study, we address these relationships in the context of rapid forest loss and the emergence of leishmania in the southern Brazilian Amazon. This region holds a great biodiversity of species, including neglected and/or unknown diseases, making it an ideal study site for examining changing disease dynamics as forest loss gives way to expanding human communities and agriculture. Our objectives include: (1) profile the potential leishmania host/reservoir wildlife community across a gradient of forest loss; (2) identify landscape metrics correlated to the prevalence of medically important vector species of sandfly; and (3) reveal positive incidence of leishmania from wild-caught sandfly samples. To address these objectives, we captured sandflies using CDC UV-light traps across 39 forested sites with varying degrees of forest loss/degradation near Sinop, Brazil. DNA from pooled sandflies was then analyzed using metabarcoding methods to elucidate both the vertebrate and vector communities.
Results/Conclusions
A total of 56,775 sandflies were analyzed using metabarcoding methods and revealed a diverse wildlife community with over 100 vertebrate species. Two known leishmania reservoir species, the nine-banded armadillo and the domestic dog, were the most frequently occurring vertebrate species as identified by the sandfly bloodmeals. Results thus far also indicate that metabarcoding can be used to differentiate among sandfly species and show Psathyromyia aragaoi as the most frequent species of sandfly identified. A number of medically important sandfly species were also identified including Nyssomyia umbratilis and Nyssomyia whitmani.
Our early results suggest that the amount of forest loss matters for the wildlife and vector communities that are known to play important roles in zoonotic disease transmission. We know that the progression of individual infection to community-wide disease outbreak is largely driven by the state of the external environment (Blaustein et al. 2012) and thus we have witnessed disease epidemics occur when humans have directly altered previously undisturbed ecosystems. Going forward, these links between wildlife hosts/reservoirs, vectors, and thresholds of forest loss will be important for predicting and mitigating disease outbreak.