Liberia declared Ebola-free for second time

By James Giahyue MONROVIA (Reuters) - Liberia was declared free of the Ebola virus for a second time on Thursday and entered a 90-day period of heightened surveillance aimed at preventing the disease from re-emerging, the World Health Organization (WHO) said. Over 11,000 people have died in West Africa since the worst Ebola epidemic on record began over 18 months ago. Liberia has been hardest hit with over 4,800 deaths, though it has also had the most success in bringing the outbreak under control. Neighboring Guinea and Sierra Leone are still struggling to end their outbreaks. "WHO declares Liberia free of Ebola virus transmission in the human population," the U.N. health agency said in a statement. It said that 42 days - twice the maximum incubation period of the virus - had passed since the last confirmed case was cured, testing negative for the disease on July 22. Dr. Francis Kateh, the deputy head of Liberia's Ebola response team, told a news conference that Liberia would remain vigilant. Liberia was declared Ebola-free in May but more cases appeared in late June and six additional cases were identified. "Today is a day to celebrate but we should not forget what we have learned," Kateh said. "As long as there are still cases in the sub-region, we are still not free." Scientists say sexual transmission is the most likely explanation for the resurgence in Liberia, since the virus can live on in semen beyond the usual 21-day incubation period. In Sierra Leone, the body of a woman who died on Saturday tested positive for the virus, less than a week after the last person confirmed to have had the disease was released from hospital. Health workers will vaccinate around 200 people who came into direct or indirect contact with the woman, the WHO said on Wednesday. (Additional reporting by Joe Bavier, Writing by Makini Brice; Editing by Keith Weir/Ruth Pitchford)