The World Health Organization declared Liberia free of Ebola on Saturday, making it the first of the three hardest-hit West African countries to bring a formal end to the epidemic.
“The outbreak of Ebola virus disease in Liberia is over,” the W.H.O. said in a statement read by Dr. Alex Gasasira, the group’s representative to Liberia, in a packed conference room at the emergency command center in Monrovia, the capital.
Just before Dr. Gasasira’s statement, Luke Bawo, an epidemiologist, showed a map depicting all of Liberia in green with the number 42 superimposed on it. This represented that two maximum incubation periods of the virus, a total of 42 days, had passed since the safe burial of the last person confirmed to have had Ebola in the country, fulfilling the official criteria for concluding that human-to-human transmission of the virus has ended.
http://www.nytimes.com/2015/05/10/world/africa/liberia-is-free-of-ebola-world-health-organization-declares.html