Despite growing concern about the effect of environmental degradation on human health, little effort has been made to quantify the effect of ecosystem damage on public health indicators such as the incidence and burden of infectious diseases. Using village-level panel data and satellite data on forest cover, I find that the average within-sample deforestation results in a 2-4.5\% increase in the probability of malarial outbreak in each village in that district, translating to 360,000 - 880,000 additional infected individuals during the course of this study. The evidence is consistent with an ecological response and the effect of deforestation on malaria cannot be explained by post-deforestation land use change, anti-malarial programs or migration. The effect is specific to malaria, with deforestation having no discernible effect on other diseases (measles, respiratory infections, dengue and diarrhea) whose disease ecology differs from that of malaria. These large effects underscore that forest conservation can have local health benefits in addition to global carbon benefits.