Malaria increases as the Rainforest Shrinks

It was recently reported in the American Journal of Tropical Medicine and Hygiene that Anopheles darlingia, a malaria-transmitting mosquito, is up to 278 times more likely to bite people in the heavily deforested areas of the rainforest than in the jungle areas.

The changes in the vegetation following deforestation results in "optimal conditions for the breeding of mosquitoes with malaria."

"Vittor’s study reported that the A. darlingi mosquito is “the primary malaria vector in the Amazon” and prefers to feed on humans. The study, which Vittor led while at Johns Hopkins University, took place in the Peruvian Amazon.

According to Vittor, most of the deforestation in the Peruvian Amazon has been due to subsistence agriculture, where locals slash and burn the forest to grow crops like plantain and cassava. After approximately five years, the land is often abandoned, and shrubs and other secondary growth take over.

Since A. darlingi prefers to live and breed in farmland and shrubby areas, its numbers are increasing as more of the forest is cut down. Vittor said other species of mosquito prefer the jungle or are equally present in forested and deforested areas. A. darlingi, however, seems to be “newly emerged” in the studied region, and its numbers are increasing.

Malaria has also been on the rise in recent years. According to Vittor, the major epidemic has passed, but in the late 1990s cases of malaria skyrocketed.

She said the deforestation of the area “may have contributed [to the malaria epidemic], it may have caused it. But certainly, I think it’s aggravating the situation.”"

The key it seems is to strike a balance between clearing the forest for economic purposes, and preserving the forest for health and biodiversity reasons.

Tags: rainforest , malarai , jungle , biodiversity