Collaboration in Civic Spheres

CDC: Haitian cholera epidemic imported by Nepalese soldiers

by Melissa Steffan July 20th, 2011

SUMMARY: According to a recent Centers for Disease Control (CDC) report, the cholera outbreak in Haiti in October 2010 was caused by contaminated river water downstream from a United Nations military camp for Nepalese soldiers. The study was conducted by  researchers in France and Haiti, and found that Nepalese soldiers in a United Nations camp near the Artibonite River likely imported the cholera accidentally. According to the researchers’ conclusions, determining the origins of the cholera outbreak reduces suspicion that the strains were deliberately imported.

BACKGROUND: On October 21, 2010, the Haitian Ministry of Public Health and Population reported the first cholera epidemic in over a century. According to the CDC, the outbreak was caused by Vibrio cholerae O1, serotype Ogawa, biotype El Tor. While media mostly linked the outbreak to the deadly Haitian earthquake in January 2010, researchers theorized that the disease was actually imported by Nepalese soldiers in the coastal plains. In order to determine the source of the cholera, the Haitian government requested support from French epidemiologists, who then conducted this French-Haitian research project between November 7 and November 27, 2010.

KEY LINK: Understanding the Cholera Epidemic, Haiti, Emerging Infectious Diseases, Centers for Disease Control, July 2011

KEY FINDINGS:

  • Background: The study monitored incoming data from 140 Haitian communities between October 16 and November 30, 2010.
  • Methodology: Researchers used several models to identify the communities most severely affected by the disease. Spatiotemporal and regression models showed that the outbreak was most severe in areas along the coastal plains and along the Artibonite River downstream of Mirebalais, where the outbreak is suspected to have begun.
  • Symptoms: Patients believed to be affected by this particular strain of cholera suffered from “profuse, acute watery diarrhea” and vomiting.
  • Origin: According to the report, findings suggest the cholera epidemic was caused by contaminated water in the Artibonite River and one of its tributaries downstream from a United Nations military camp of Nepalese soldiers. The study states, “The start of the cholera epidemic was explosive in Lower Artibonite … It peaked within 2 days and then decreased drastically until October 31.”
  • Cause: According to the research, the strains of cholera bacteria in this outbreak were non-indigenous. Based on the remote area, Meille, in which the cholera first appeared, Nepalese soldiers likely imported the bacteria accidentally upon arrival from another area experiencing a cholera outbreak. The data suggest an exact correlation between the soldiers’ arrival and the Meille outbreak, the study reported. However, other factors were also at play. These included, “The absence of immunity among the population, (and) the higher infectivity of epidemic strains shed in human rice-water stools (versus) environmental strains, and the role of hypervirulent variant strains in provoking epidemics.”
  • Recommendations: The study recommends not only that military camps handle sewage more effectively, but also that international aid organizations understand the risks that foreign diseases pose to people who have not been exposed to certain bacteria.

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