Global Change and the Ecology of Vector-Borne Disease

Parsons Environmental Science Seminar

Global Change and the Ecology of Vector-Borne Disease

Prof. Erin Mordecai
Biology Department
Stanford University

Global anthropogenic changes in climate, land use, species invasions and extinctions, and population growth and movement are rapidly transforming the Earth's ecosystems and with them, the landscape of human health. Vector-borne diseases spread by mosquitoes and other biting arthropods are particularly prone to responding to global change because transmission depends on climate and habitat and how humans interface with them. In this talk, I present our work on how changing climate and land use affect a range of diseases including malaria, dengue, and Zika, and how humans can respond to that changing risk. Our work shows that understanding vector ecology is critical for predicting changes in disease burden because many responses are nonlinear and complex. By taking a mechanistic approach we show that intermediate temperatures (25-29°C) are optimal for transmission of malaria, dengue, and other pathogens, suggesting that warming climate will shift, rather than expand, the seasonal and geographic burden of disease. At a local scale, climate interacts with land use to determine vector abundance, biting rate, and infection rates in humans. Urban and sub-urban vectors like Aedes spp. do not occur in forests or forest edges, suggesting that intact forest might prevent dengue and Zika spread. By contrast, Amazonian malaria vectors thrive in forest edge habitats, and incidence is highest at edges created by deforestation. Finally, we show evidence that human behavior responds to malaria risk by reducing deforestation in the highest-incidence sites. Better understanding the complex and often nonlinear ecology of vector transmission is critical for predicting how future anthropogenic changes will affect human health—and for mitigating their impacts.