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Cambridge University Science Magazine

Following the earthquake in Haiti in January 2010, thousands of families were displaced from their homes and were forced to find shelter in relief camps. The lack of adequate sanitation in these camps provided an ideal environment for an outbreak of cholera, an acutely dehydrating diarrheal disease caused by the bacterium Vibrio cholerae, which is usually transmitted through contaminated water. In October, the first cases of cholera infection were reported; in the weeks since then at least 2,100 people have died from the disease.

A study published in the New England Journal of Medicine used advanced DNA sequencing techniques to characterise bacteria from Haiti and other regions of the world to assess the likely origin of the outbreak. The results show that the Haitian epidemic is clonal, and the strain isolated from Haitian patients is almost identical to the seventh-pandemic El Tor O1 strains that are predominant in South Asia. These strains differ from those circulating in Latin America and the Gulf Coast, suggesting that the Haitian outbreak, unlike other cholera epidemics, did not arise from the local aquatic environment or regional climatic events. Instead, the data strongly suggest that the Haitian epidemic began with the human introduction of a V. cholerae strain from a distant geographic source. These findings, together with the time and location of the outbreak, support speculation that the disease was introduced by United Nations peacekeeping troops arriving from South Asia—although further investigation is required to find the actual source.

Written by Robert Jones