West Africa’s Ebola outbreak is not over, after all.
Less than 24 hours after the World Health Organization declared Liberia — the last country to have reported known cases — free of the disease, it announced Friday that a new case has been discovered, this time in neighboring Sierra Leone.
The case was of a 22-year-old woman who is already dead, agency spokesperson Gregory Hartl said on Twitter.
Read more: Ebola outbreak declared over at last
An investigation is underway to see how the woman became infected in a country where transmission of the virus was thought to have stopped several months ago. The country was declared Ebola-free on Nov. 7.
Media reports said the case occurred in Tonkolili province, in the center of the country.
The WHO statement did not offer information as to how the woman became infected. But it called the case a “flare-up” — a term that is becoming synonymous with infections that occur through contact with an Ebola survivor.
Ebola viruses can remain in a survivor’s body for months in places — eyeballs, testicles — where the immune system can’t easily attack them. Men who survive Ebola are known to emit viruses in their semen for months after their recovery.
When the WHO declared Liberia free of Ebola on Thursday, it warned further flare-ups were possible.
In its statement Friday, the global health agency said health officials in Sierra Leone had reacted rapidly to the newly reported case. But the fact the woman was only detected as an Ebola case after her death does not speak well of surveillance efforts. Further, there are reports the woman sought care at a hospital but was not recognized as an Ebola case and was allowed to leave.
The West African Ebola outbreak, far and away the largest the world has ever seen, has been ongoing since at least December 2013. More than 28,600 people have been infected and more than 11,300 have died.
Helen Branswell can be reached at helen.branswell@statnews.com
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