NPR’s “Shots” blog reports on efforts to determine the source of Haiti’s cholera epidemic, writing, “Most researchers currently believe that United Nations peacekeeping soldiers introduced cholera to Haiti in October of 2010,” but researchers from the University of Maryland report they “have found two very different cholera strains in some of the first Haitians to be struck by the disease.” According to the blog, “One is a so-called 01 serotype with close resemblance to the Nepalese strain, found in about half the patients sampled,” while “[t]he other is a type called non-01/O139 that has never been known to cause an epidemic; it was found in 21 percent of patients.”

“‘This suggests that it’s very likely that local (Haitian) strains are involved,’ [lead researcher Rita Colwell] told Shots,” the blog writes. “Because no one has tested for pathogenic cholera strains in that country before, we have no evidence that it wasn’t there already,” she added, according to the blog. “Colwell, an internationally recognized expert on the interaction of cholera and environmental factors, thinks Haiti’s explosive epidemic is most likely explained by the ‘perfect storm’ of three converging factors” — an earthquake in January 2010 disrupted rivers, causing them to become alkaline; one of the hottest summers on record in Haiti warmed “estuaries where cholera likes to breed in tiny crustaceans”; and a hurricane that skirted the country caused heavy rain and flooding (Knox, 6/18).