The latest flare-up of Ebola in Sierra Leone has ended, leaving no confirmed cases of the deadly virus in West Africa, the U.N. health agency said Thursday. "The World Health Organization (WHO) joins the government of Sierra Leone in marking the end of the recent flare-up of Ebola virus disease in the country," it said in a statement 42 days-or two Ebola incubation cycles-after Sierra Leone's last Ebola patient tested negative for the second time. Sierra Leone recorded half the cases in an Ebola epidemic that infected nearly 29,000 people across three West African countries and killed more than 11,000 people since December 2013, although a significant number of deaths are believed to have been unreported. The WHO also warned Thursday that a recurrence of the tropical disease remained possible. "WHO continues to stress that Sierra Leone, as well as Liberia and Guinea, are still at risk of Ebola flare-ups, largely due to virus persistence in some survivors, and must remain on high alert and ready to respond," the agency said. The virus can stay in one bodily fluid for at least nine months after a patient has recovered, six months longer than previously thought. Scientists are working to establish how long it can persist in other bodily fluids and tissues such as the spinal column and the eye, and for how long it could remain infectious.
