Tests on a 22-year-old woman who died earlier this month in Sierra Leone's north proved positive for the virus, Francis Langoba Kelly, spokesman for the Office of National Security, told a local radio program. She came from the Northern Kambia District and went to the Northern Tonkolili District for medical attention, he said.
Authorities are tracing her contacts and have dispatched teams to the area for investigations. Certain areas will be quarantined, he said.
WHO declared an end to the deadliest Ebola outbreak ever yesterday after no new cases emerged in Liberia. It had been at least a month since Ebola had been seen in Guinea or Sierra Leone.
The three countries were most affected by the epidemic that began two years ago. "Our level of preparedness and response capabilities are very high and there is no cause for concern," said Kelly.
"We encourage the public to continue to practice the hygiene regulations which were in force during the period while Ebola was raging and the emergency regulations are still in force."
Nearly 4,000 people had died before Sierra Leone was declared free from transmission of Ebola on November 7. Guinea marked that day on November 29. Liberia was first declared free of the disease in May, but new cases emerged two times forcing officials there to restart the clock.
Yesterday marked its third time being declared free from transmission. Ebola has killed more than 11,300 people, mostly in West Africa, since it emerged at the end of 2013. WHO declares Ebola transmission over when a country goes through two incubation periods 21 days each without a new case emerging.
Countries are then placed on a 90-day heightened surveillance. Ebola is spread through direct contact with the bodily fluids of people who are sick or bodies of the dead.