Deforestation in Rondonia, Brazil. Image courtesy of Planet Labs and Wikimedia commons.
Summary: Land use, land cover and climate are rapidly changing across the tropics and developing world. Changes including forest fragmentation and loss, urbanization and increasing temperature are having profound effects on the transmission of vector-borne diseases from malaria to dengue, and yellow fever to leishmaniasis. These processes of global change and resulting impacts on vector-borne disease transmission are particularly pronounced in Latin America, where the world's largest remaining tropical forest is steadily being cleared for pasture and agriculture, and recent epidemics of Zika virus and a resurgence of malaria, for example, figure prominently in the public health landscape. Within this complex landscape, we have developed a core research agenda tackling numerous questions at the interface of global change and vector-borne disease transmission:
1. Deforestation and malaria transmission in the Brazilian Amazon: As a National Science Foundation Postdoctoral Research Fellow at Stanford University, I developed and led a project investigating feedbacks between land use change, forest loss and human malaria in the Amazon basin. Using geospatial data processing and analysis in Google Earth Engine, coupled with panel data statistical techniques from applied econometrics, this project identified a strong positive effect of deforestation on malaria transmission in the interior of the Amazon, but the effect is weaker on the fringe where much forest has already been cleared. In addition, we also find strong evidence that human malaria burden reduces rates of deforestation in the interior of the Amazon, but this feedback is absent on the fringe (study published in PNAS). This is among the first evidence for an effect of disease burden on land use change, and highlights the importance of socio-ecological feedbacks in disease ecology. Below: timelapse of fishbone deforestation in the state of Rondonia, Brazil (Google Earth Engine).
2. Effect of urbanization, temperature and precipitation on dengue transmission: Ongoing geospatial and large-scale statistical analyses are investigating the effects of urbanization over the past decade on dengue transmission in Brazil. This work is making use of large spatial datasets and the Google Earth Engine Platform coupled with disease reporting data from the Brazilian Ministry of Health to identify the effects of land use change on disease transmission across space and time. This project is being led under my supervision by a Bay Area High School student, Akshara Vykunta.
Further, collaborative projects are investigating 1) the roles of temperature and precipitation on dengue epidemics in San Juan, Puerto Rico using empirical dynamic modeling approaches (led by Stanford PhD student, Nicole Nova, and published in Ecology Letters), and 2) the effects of land use change on Zika, chikungunya, dengue and malaria transmission in Colombia (led by Stanford Masters student, Songhee Han). These projects are in collaboration with the Mordecai lab in the Department of Biology at Stanford University. |
3. Land use change and the changing landscape of vector-borne disease in Latin America: This project is in collaboration with the Mordecai lab and Natural Capital Project at Stanford University, as well as Andres Lescano at Universidad Peruana Cayetano Heredia in Peru, and Centro de Innovacion Cientifica Amazonica (CINCIA), a Peruvian NGO. We are exploring how vector transmission niches shift across the landscape as climate and land use change in Latin America using a combination of mathematical modeling techniques, species distribution models, large-scale geospatial and panel data statistical approaches, as well as field sampling of vectors and the environment in the Peruvian Amazon region. This project has recently been funded by the NSF EEID Program.