Medical detectives working in Haiti believe the bacterium that caused the recent cholera epidemic most closely resembles a strain commonly found in South Asia.
The analysis isolated DNA from bacterial samples taken from cholera victims in Haiti. All 13 of those samples were identical, showing that the outbreak in Haiti most probably comes from a single strain.
More studies may be able to pin down the source more precisely, though experts say that's only a possibility. The work was a collaboration between Haitian public health workers and the U.S. Centers for Disease Control and Prevention in Atlanta.
"Although these results indicate that the strain is non-Haitian, cholera strains may move between different areas due to global travel and trade," Dr. Alex Larsen, Haiti's Minister of Health, said in a statement. "Therefore, we will never know the exact origin of the strain that is causing the epidemic in Haiti. This strain was transmitted by contaminated food or water or an infected person."
Rumors have been circulating in Haiti that a contingent of United Nations peacekeepers from Nepal brought the bacterium into the country. UN teams say they've tested those peacekeepers, and found no traces of cholera.
A UN spokeswoman tells NPR that more tests are being conducted and it’s uncertain when the results will be known.
The country is bracing for what is currently predicted to be Hurricane Tomas. The U.S. National Hurricane Center has it scoring a direct hit on Port au Prince this Friday.