A new study shows that deforestation in the Amazon helps spread disease by creating an optimal environment for malaria-carrying mosquitoes. The study, published in the online issue of the CDC journal Emerging Infectious Diseases, found that clearing forests in the Brazilian Amazon raised incidences of malaria by almost 50 percent.
“It appears that deforestation is one of the initial ecological factors that can trigger a malaria epidemic,” says Sarah Olson, the lead author of the new report and a postdoctoral fellow at the Nelson Institute, Center for Sustainability and the Global Environment with the University of Wisconsin-Madison.
Researchers combined information on malaria occurrences in 54 Brazilian health districts with satellite imagery of Amazon deforestation.
“The deforested landscape, with more open spaces and partially sunlit pools of water, appears to provide ideal habitat for this mosquito,” Olson says of Anopheles darlingi, the primary carrier of malaria in the Amazon. In deforested areas Anopheles darlingi displaces other less-malaria prone mosquitoes that favor forest landscapes.
“A 4 percent change in forest cover was associated with a 48 percent increase in malaria incidence in these 54 health districts,” explains Olson. “The health data used in the study is of the highest quality and spatial resolution. Unlike previous studies, our data allowed us to zoom in on areas where people are being exposed to malaria and to exclude areas where they are not being exposed.”
The study adjusted for human population, access to healthcare, and additional factors, yet still found malaria outbreaks closely aligned with deforestation.