The cholera epidemic that has crippled Haiti was first spread by United Nations troops, said a report written by a French scientist sent to Haiti to assist Haitian health officials. Epidemiologist Renaud Piarroux said that although further investigation is needed, he could form “no other hypothesis” to explain the cholera outbreak that originated in a tributary of Haiti’s Artibonite River, next to a U.N. base outside the town of Mirebalais. Piarroux also hinted strongly that there had been a cover-up. The U.N. said there is no conclusive evidence that their base was the source of the outbreak. Until this outbreak, there had not been any documented outbreaks of cholera of Haiti. Nepalese troops earlier confirmed they had replaced a leaking pipe and the U.S. Centers for Disease Control and Prevention confirmed in October this strain of cholera originated in South Asia.