Destruction of Tropical Forests Leads to Steep Rise in Malaria, Study Says

A new study directly links clearing of forests in the Amazon with a pronounced jump in malaria cases. University of Wisconsin researchers, analyzing data from one county in Brazil, said they found a 48 percent increase in malaria cases after 4.2 percent of the country’s tree cover was cleared. “It appears that deforestation is one of the initial ecological factors that can trigger a malaria epidemic,” said researcher Sarah Olson. Comparing satellite photos showing loss of tree cover with GPS data marking where malaria victims in the county lived, the scientists demonstrated that areas that have not been deforested have considerably lower per capita rates of malaria. Reporting in the journal Emerging Infectious Diseases, the researchers said malaria apparently spread rapidly in deforested areas because the altered landscapes provide suitable larval habitats for malaria-carrying mosquitoes, including ditches, dams, mining pits, vehicle ruts and — in the case of the county in Brazil — fish farms. Some studies have shown that draining such areas and clearing brush around homes can help reduce rates of malaria.