WASHINGTON (Reuters) - DNA tests show the cholera strain that has killed more than 300 people is most closely related to a strain from South Asia, U.S. health experts said on Monday.
The so-called DNA fingerprinting shows various samples of cholera taken from Haitian patients are identical to one another, and of all the known strains, they most closely resemble one from South Asia, the U.S. Centers for Disease Control and Prevention said.
Health officials said the findings do not prove anything, but the revelations may fan the flames of rumors that United Nations peacekeepers from Nepal brought the cholera. This, in turn, may worsen tensions leading up to elections later this month.
"Although these results indicate that the strain is non-Haitian, cholera strains may move between different areas due to global travel and trade," Haiti's Minister of Health, Dr. Alex Larsen, 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."
More than 4,700 people have been sickened in the outbreak of cholera, the first in Haiti in decades. Health officials fear it will continue to spread because after January's devastating earthquake so many people live in camps, without reliable access to clean water.
Last week the U.N. said it was taking "very seriously the allegations that sewage water coming from latrines at the back of the Nepalese military base" could be the source of the outbreak.
It said all 710 Nepalese soldiers had "all required medical tests prior to their deployment in Haiti."
"None of them is cholera-positive," said the U.N., which maintains a 12,000-strong peacekeeping force in Haiti.
CDC medical epidemiologist Dr. Jordan Tappero, who leads the CDC cholera response team in Haiti, said the main focus is controlling the outbreak and not looking for the source of the bacteria.
"We realize that it's also important to understand how infectious agents move to new countries. However, we may never know the actual origin of this cholera strain," he said.
Cholera is spread by contaminated human feces, usually via water. It can be prevented with good hygiene and carefully disinfected water, usually using chlorine.
But when an outbreak is active, it can get into food and be carried around on people's hands and shoes.
Cholera is usually easy to treat with simple rehydration salts, but in some cases severe diarrhea and vomiting dehydrates a patient quickly and kills within hours.
There is a vaccine but Haiti was not considered an at-risk zone. Most people infected with cholera do not have any symptoms but they can spread it for up to two weeks.