Shift in weather pattern concern for human health

marks the di erence between a tolerable environment and one that causes intense human su ering.

ese patterns are a boon for certain vector-borne illnesses — de ned as infections transmitted by an organism (usually an arthropod, a category that includes insects and arachnids). Regions of the world that will experience longer wet seasons because of El Niño, many of which are in the tropics, may see an increase in mosquito-borne illnesses, according to Victoria Keener, a senior research fellow at the East-West Centre in Honolulu, Hawaii, and a coauthor of the upcoming Fifth National Climate Assessment.

“El Niño will mean a longer breeding season for a lot of vectors and increased malaria potential in a lot of the world,” she said.

A 2003 study on the intersection of El Niño and infectious disease showed spikes in malaria along the coasts of Venezuela and Brazil during and after El Niño years. e study looked at more than a dozen cycles between El Niño, La Niña, and the cycle’s “neutral” phase, which taken together are known as the El Niño-Southern Oscillation, or ENSO. e researchers, who analysed data dating back to 1899, also found an increase in malaria during or post-El Niño in Colombia, India, Paki- stan and Peru. Cases of dengue, another mosquito-borne illness, increased in 10 Paci c islands. e manner in which El Niño impacts mosquitos and the diseases they carry is varied and often di cult to accurately calculate, said Christopher Barker, an associate professor in the Department of Pathology, Microbiology and Immunology of the University of California Davis School of Veterinary Medicine. Mosquitos breed in warm, wet conditions. But too much water in the form of ooding rains can wash away mosquito larvae and ultimately contribute to a decrease in mosquito populations.