Brazil's deforestation linked to increased malaria incidence, study says

Jun 19 2010

Deforestation in Brazil has been linked to an increase in malaria incidence there, according to findings published online Wednesday in the CDC journal, Emerging Infectious Diseases, Agence France-Presse reports.

For the study, researchers "examined 2006 data tracking malaria rates in 54 Brazilian health districts and high-definition satellite imagery showing the extent of logging of nearby forests," the news service writes (6/17). According to a University of Wisconsin-Madison press release, "[t]he health districts reflected in the ... study are typical of many of the thousands of such districts spread across Brazil and its Amazon region. Since 2001, the Brazilian Ministry of Health has similarly monitored and treated malaria in more than 7,000 districts" (6/16).

The study "found a 48 percent increase in malaria cases in one county in Brazil after 4.2 percent of its tree cover was cleared," Reuters reports, noting that the data examined was "exceptionally detailed."

Brazil has about 500,000 malaria cases each year, mostly transmitted by the Anopheles darlingi mosquito. "Human-altered landscapes provide a milieu of suitable larval habitats for Anopheles darling[i] mosquitoes, including road ditches, dams, mining pits, culverts, vehicle ruts, and areas of poor clearing," the researchers wrote in the journal (Fox, 6/16).

"The deforested landscape, with more open spaces and partially sunlit pools of water, appears to provide ideal habitat for this mosquito," said Sarah Olson, lead author of the study and a postdoctoral fellow at the Nelson Institute, Center for Sustainability and the Global Environment, AFP writes (6/17).

Jonathan Patz, the professor who oversaw the research, said the findings "are likely generalizable to many parts of Amazonia, and build on our past entomological studies in the Peruvian Amazon." Patz said the study indicates "that rain forest conservation policy should be a key component to any malaria control effort in the region," Reuters reports (6/16).