The Ebola virus (shown here in red between infected monkey cells) resurfaced in Sierra Leone just hours after WHO had announced the end of the outbreak in West Africa.

The Ebola virus (shown here in red between infected monkey cells) resurfaced in Sierra Leone just hours after WHO had announced the end of the outbreak in West Africa.

NIAID

Ebola is back … or never left

It was a short-lived celebration. Just hours after the World Health Organization (WHO) declared the Ebola outbreak in West Africa over on Thursday, Sierra Leone reported a new case of the disease to WHO. A 22-year-old woman, who had died earlier in the week, had tested positive for the virus. WHO confirmed the case on Friday. “A joint team of local authorities, WHO, and partners are investigating the origin of the case, identifying contacts, and initiating control measures to prevent further transmission,” WHO said in a statement.

The details of the case are troubling. The young woman was a student in Lunsar, a town in the district of Port Loko, says Christopher Dye of WHO. Around Christmas she traveled from there to Kambia district, closer to the border with Guinea, and stayed there until 6 January. “We suspect that was the time of onset of the illness,” Dye says. “Having become ill she decided to go home, and her family home is in Tonkalili.” The young woman went to a hospital but was not recognized as an Ebola case. “She got progressively worse and died. The process of preparing her body for burial and the burial itself were done unsafely,” Dye says. “That is of course not what we would have liked to have seen happen in light of all the Ebola cases we had.”

As a consequence, there are a number of people who came into contact with the woman that are at high risk of having been infected with ebolavirus. There were 27 contacts listed on Thursday night, Dye says. “But I would almost certainly expect that figure to be revised upwards.” A vaccine produced by Merck that protected people from the deadly virus in a trial in Guinea last year may be given to these people and their contacts. “The plan is to do a ring vaccination with this vaccine,” Dye says. “Obviously it has to be done very quickly. There is vaccine available and there is support from the vaccine teams in Guinea, some of which will cross the border to help the health authorities in Sierra Leone carry out the vaccinations.” 

Even as WHO officials had announced on Thursday that for the first time in 2 years, West Africa was free of Ebola transmission, they had warned of the risk of flare-ups. Because ebolavirus can persist in some tissues and bodily fluids of survivors for months, there is a danger that they can pass the virus on to others, for instance, through unprotected sex. That also seems a likely explanation in the new case, says Vincent Munster, a virologist at the Rocky Mountain Laboratories of the U.S. National Institute of Allergy and Infectious Diseases in Hamilton, Montana. "I think we have to remain vigilant for quite some time”.

The new case was discovered because the authorities in Sierra Leone routinely swab dead bodies for Ebola. That the case was not recognized earlier and the women had an unsafe burial point to weaknesses in the system, however, Dye says. “We’re really troubled by these things and there is a huge feeling of disappointment.” The testing of possible Ebola patients should be done just as effectively as the swabbing of bodies, he says.

Sierra Leone was declared free of Ebola on 7 November 2015, and was in a 90-day period of heightened surveillance. Media reports that the woman who died of Ebola had gone to a hospital and been sent home call into question how prepared hospitals are in West Africa to deal with the virus even after the biggest Ebola outbreak on record.

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