Nigeria’s is set to join Senegal as the West African countries that have seen Ebola and successfully contained it.
WHO gives a period of 42 days, which is double the normal incubation time of the Ebola virus, to ensure that there are no new cases in the country.
Nigeria had 20 cases of Ebola after a Liberian-American man named Patrick Sawyer flew into Lagos collapsed at the airport. Health care workers treating Sawyer were infected, and as it spread it ultimately killed eight people.
“It’s possible to control Ebola. It’s possible to defeat Ebola. We’ve seen it here in Nigeria,” Nigerian Minister of Health Onyebuchi Chukwu told TIME. “If any cases emerge in the future, it will be considered—by international standards—a separate outbreak. If that happens, Nigeria will be ready and able to confront it exactly as we have done with this outbreak.”