Recent outbreaks of arboviral diseases such as Zika and West Nile have their roots in tropical forests.
Their spread coincides with significant land conversion for agriculture, impacting arthropod vectors and
reservoirs of zoonotic diseases. Our decade-long epidemiological studies in Panama's Darien region indicate
high incidence of zoonotic alphaviruses in humans, wildlife and more recently, in livestock. In Darien, open
pasture ranching and crop farming coexist with agroforestry, an important climate change mitigation strategy that
integrates crops, livestock and forest. Despite the rising global adoption of agroforestry, its impact on infectious
disease risk is understudied. Our research aims to fill this knowledge gap by investigating zoonotic arboviral
transmission in Darien in relation to its agricultural practices, including agroforestry. Various factors, from
biodiversity shifts to land tenure benefits and irrigation schemes, likely influence disease transmission. We
hypothesize that landscapes that merge forest, agriculture and human dwellings potentially enhance the spread
of zoonotic arboviruses due to increased overlap of vectors, vertebrate reservoirs including livestock, and
humans.
Our first aim in this study is to assess agroforestry's impact on zoonotic arboviral risk among the agrarian
population and livestock in Darien, Panama, by conducting serosurveys and acute febrile studies to inform
habitat suitability modeling. Interviews with participants will provide data on health and social determinants
influencing agriculture and zoonoses interactions. Our second aim is to characterize vector ecology, infection
rates, and host use across an agricultural gradient. We will study immature vector breeding preferences and
water quality, and employ a variety of vector trapping methods to assess viral transmission rates and blood meal
origins to shed light on shifts is host usage within agroforestry environments. Our third aim is to map zoonotic
arboviral risk using geospatial and field data. We will also analyze natural selection and gene flow of the
predominant zoonotic arbovirus in the region, Venezuelan equine encephalitis virus, across the agricultural
gradient. We will use genomes derived from field isolates (mosquito, animal and human), along with regional
historical isolates, to test the hypothesis that increased host diversity at the forest/agriculture ecotone fosters
greater VEEV genetic diversification, leading to the emergence of new variants capable of causing epizootics.
The research outcomes will be instrumental in defining transmission dynamics and health burden of
significant zoonotic arboviruses and informing preventive measures. This understanding will guide land use and
health policies in Darien, serve as a blueprint for interventions, and help ensure alignment of climate and health
objectives within the context of agroforestry. Our methodologies and findings will have broad applicability across
regions with similar ecologies.
