United Nations (CNN) -- The cholera outbreak that killed more than 4,500 people in Haiti last year was linked to peacekeepers from Nepal, a new report says, a conclusion previously resisted by at least some United Nations officials.
The report, released late Wednesday by a United Nations-appointed independent panel of experts, says that the cholera strain did not originate in Haiti. Instead, it was "very similar" to strains of cholera currently circulating in South Asia.
The report does not directly blame the peacekeepers, saying rather that the Haiti cholera outbreak was caused by a "confluence of circumstances" and "was not the fault of, or deliberate action of, a group or individual."
The circumstances that aggravated the cholera strain into a full-blown outbreak included deficiencies in Haiti's "water and sanitation and health care system" the report states. In addition to the 4,500-plus deaths, almost 300,000 others were sickened in the outbreak.
A French epidemiologist, Dr. Renaud Piarroux, had suggested in December that the Nepalese soldiers were the source of the outbreak. At the time, a spokesman for the U.N. mission in Haiti indicated that officials viewed his report with some skepticism.
The first cases of the outbreak occurred in late October last year. The Nepalese contingent of peacekeepers arrived in Haiti "between October 8th and 24th, 2010, after three months of training in Kathmandu, Nepal," the report says.
Haiti at the time was already reeling from the devastating 7.0-magnitude earthquake that hit the island nation in January 2010, killing more than 220,000 people, injuring more than 300,000 and leaving more than 1 million homeless.
According to the report, fecal matter from the U.N. camp where the Nepalese were based was improperly routed by a contractor into the Artibonite River system, and "this contamination initiated an explosive cholera outbreak downstream in the Artibonite River Delta and eventually throughout Haiti.
"This explosive spread was due to several factors, including the widespread use of river water for washing, bathing, drinking, and recreation," the report says. There was "regular exposure of agricultural workers to irrigation water from the Artibonite River," it says.
The report provides recommendations for future U.N. missions, including "United Nations personnel and emergency responders traveling from cholera endemic areas should either receive a prophylactic dose of appropriate antibiotics before departure or be screened."
In addition, it says, "to prevent introduction of contamination into the local environment, United Nations installations worldwide should treat fecal waste using on-site systems that inactivate pathogens before disposal."
U.N. Secretary-General Ban Ki-moon, who commissioned the report, on Thursday expressed his "deepest sympathies to the victims" and said he will convene a task force to follow up on the report's recommendations.
The December report from Piarroux, based on an investigation he led in November, noted that many of the early victims of the outbreak were getting their water from the Artibonite River downstream from the U.N. peacekeeper camp. At one village, Piarroux said, residents told his team that they had seen pipes from a septic tank in the camp dumping a nauseating substance into the river.
He noted that although Kathmandu had been experiencing a cholera outbreak while the peacekeepers trained there, none of the soldiers came forward with symptoms and none of the samples collected from the camp registered positive for cholera.
But according to the Centers for Disease Control and Prevention website, people can carry the cholera bacteria and experience no symptoms of the disease. And Piarroux suggested that officials could have taken steps after the outbreak began that would have erased traces of infection in the camp.
U.N. and Nepalese officials had repeatedly denied that the cholera originated in the Asian nation.
Vincenzo Pugliese, spokesman for the U.N. mission in Haiti, said in December that Piarroux's report failed to deliver definitive proof. "We have not dismissed the report but we have not accepted it completely," he said. "We remain open to investigating this and we will get to the bottom of it."