PORT-AU-PRINCE, Haiti — a contingent of U.N. peacekeepers is the likely source of a cholera outbreak in Haiti that has killed at least 2,000 people, a French scientist said in a report obtained Tuesday by the associated Press.

Epidemiologist Renaud Piarroux concluded that the cholera originated in a tributary of Haiti’s Artibonite river, next to a U.N. base outside the town of Mirebalais. He was sent by the French government to assist Haitian health officials in determining the source of the outbreak, a French Foreign Ministry official said Tuesday.

“No other hypothesis could be found to explain the outbreak of a cholera epidemic in this village … not affected by the earthquake earlier this year and located dozens of kilometers from the coast and (tent) camps,” he wrote in a report that has not been publicly released.

The report also calls for a further investigation of the outbreak, improved medical surveillance and sanitation procedures for U.N. peacekeeping troops and better support for Haitian health authorities.

The AP obtained a copy of the report from an official who released it on condition of anonymity. Piarroux confirmed he had authored the report but declined in an e-mail interview to discuss his findings. Copies were sent to U.N. and Haitian officials, the foreign ministry confirmed.

U.N. spokesman Martin Nesirky told reporters in new York that there is still no conclusive evidence that its base was the source of the outbreak. He said the organization “remains very receptive to any scientific debate or investigation on this.”

The report’s revelation comes on a day of high tensions in Haiti, as people anxiously await the results of the disputed Nov. 28 presidential election and potential resulting violence.

Piarroux could not prove there was cholera inside the base or among the soldiers, a point the U.N. has repeatedly used to deny its soldiers brought the disease to Haiti or that its sanitation procedures were responsible for releasing it into the environment. He writes that military doctors said there were no instances of cholera within the unit.

But he also hinted strongly at a cover-up.

“It can not be ruled out that steps have been taken to remove the suspected fecal matter and to erase the traces of an epidemic of cholera among the soldiers,” he wrote.

The report also notes that septic tanks and pipes that would have helped to confirm sanitation problems and the presence of the bacteria were no longer at the base when he visited.

Nepalese troops earlier confirmed they had replaced a leaking pipe, which contained a foul-smelling runoff that the U.N. denies was human waste, between two visits by an AP reporter in October. the AP also found the local contractor dumped waste into overflowing pools dangerously close to a hillside that drains into the river.

Piarroux’s is the first scientific report linking the base to the epidemic, though many other epidemiologists and public health experts have said for weeks that the soldiers are the most likely source of the infection.

Other scientists and experts say it is possible that ocean currents or other climate-related events carried the bacteria to Haiti. Further studies on bacterial samples that could address those questions are ongoing.

The U.S. Centers for Disease Control and Prevention confirmed in October that the strain of cholera bacteria in Haiti matched one from South Asia, a region that includes Nepal, but said it had no further information about the cause of the outbreak at the time.

Many Haitians have long suspected the Nepalese base was the source of the disease, and anger at the troops sparked a week of riots in which U.N. soldiers were injured and several Haitians were killed.

The report says that the first cases of the disease were from the village of Meille, where the base is located. the first confirmed case, a 20-year-old man from the village, developed symptoms on Oct. 14 and was found by Cuban doctors at a hospital in nearby Mirebalais.

Haitian investigators “indicated that the first patients were obtaining drinking water from a tributary of the Artibonite River flowing just below the (U.N.) base,” he said.

It notes that the rotation of soldiers began arriving days before those first cases from Nepal, where there were cholera outbreaks over the summer.

It goes on to describe how the disease flowed into the Aribonite River before “exploding” in the delta where the river meets the sea. Hundreds of cases were reported within days, before the outbreak spiraled out of control to infect the entire county.

Until this outbreak there had not been a diagnosed case of cholera in Haiti as far back as records go in the mid-20th Century, Claire-Lise Chaignat, head of the global task force on cholera control at the World Health Organization, said in October. There were suspected cases a century before, but experts say it would have likely been a different strain than the ongoing El Tor pandemic.

The disease was totally unknown to today’s Haitians, who had developed no immunity against it and had no information on how to fight it until aid workers mobilized after the outbreak. Terror over its fast-killing power has triggered attacks on cholera treatment centers and a witch-hunt in rural Haiti. At least 12 people were killed on accusations they used magic to spread the disease.

For the first critical month of the outbreak, the United Nations, U.S. Centers for Disease Control and Prevention, World Health Organization and others said that an investigation into how the disease arrived in Haiti was not necessary and could in fact be harmful. Those who asked questions about it were accused of playing “the blame game.”

It was not until AP reports of sanitation problems at the base and calls by experts including Paul Farmer, a physician and U.N. official, for a thorough investigation that the matter was seriously discussed in public.

Farmer said there were compelling public health reasons to find the source of the infection, including finding information to help prevent its further spread, and that avoiding the questions was a matter of politics.

The U.N. mission confirmed to AP last month that a French epidemiologist had met with met with U.N. peacekeeping mission chief Edmond Mulet in Port-au-Prince to discuss his findings. At the time the mission denied that he had implicated the peacekeepers, but acknowledged that it was now taking the allegations about its base more seriously than when rumors first arose.

On Tuesday the mission said the report was still not definitive.

“We have neither accepted nor dismissed his findings, as it’s one report among others,” U.N. mission spokesman Vincenzo Pugliese said. “The Nepalese contingent in Mirebalais is just one piece of the cholera puzzle, since there is no conclusive evidence at this point that the Nepalese camp was or was not the source of the epidemic.”

In roughly six weeks the disease has spread to every region of the country and sickened nearly 100,000 people. the U.N. says the death toll could be twice the official count and that up to 650,000 people in Haiti could get cholera over the next six months.

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