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 infected 22-year-old woman is already dead.
A senior World Health Organization official said the global health agency is braced for more cases as a consequence of this event.
Christopher Dye, director of strategy in the WHO director-general’s office, told STAT the young woman traveled significant distances in a series of taxis while ill, coming in contact with people who may be hard to trace. She was cared for at a hospital that didn’t recognize her as an Ebola case, possibly leading to exposure for health workers who treated her.
She was cared for at home, in a dwelling shared by 22 other people. And after her death, her body was given a traditional burial, with family members washing and touching the deceased. The corpses of people who have died of Ebola teem with viruses and unsafe burials often end up igniting new cases.
Dye said investigations are 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 — 42 days after its last case was diagnosed.
There are three possibilities, Dye explained. She could have been part of an undetected chain of transmission that was never stopped. She might be an Ebola survivor, who suffered a relapse — similar to the case of Scottish nurse Pauline Cafferkey. Or she could have contracted the infection through contact with an Ebola survivor.
Dye said he thinks the last scenario is the most likely.
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.
In addition to trying to figure out how the young woman was infected, responders are scrambling to find people who came in contact with her during her illness. As of Thursday night, 27 contacts have been identified, but Dye expects that number will rise and that some of the contacts will become sick.
“I am anticipating that during the journey and the latter stages of her illness, others may have become infected. So we’re going to be very prepared for that,” he said. That said, Dye expressed confidence that Sierra Leone knows how to deal with the situation.
“I have no doubt that this will be brought under control, because Sierra Leone has the capacity to do that. There are many very experienced people who are already working on this outbreak. So there’s no question of this getting out of control in any way, but we don’t yet know exactly what the consequences are for these exposures to infection.”
Still, the fact that the case was only diagnosed after death is troubling. Ideally, the hospital where she sought care should have suspected Ebola and isolated her while waiting for test results. Instead, she was allowed to go home.
Contacts of the woman will be offered Merck’s experimental Ebola vaccine, Dye said. Designed by scientists at Canada’s National Microbiology Laboratory, the vaccine has appeared to be highly effective in testing so far.
The young woman was a college student in the district of Port Loco in western Sierra Leone. Around Christmas, she went on vacation to Kambia, a district in the north which is near the border with Guinea. While there, she became ill and decided to go home to her family, in Tonkolili district, in the center of the country.
She traveled in a series of three taxis, likely sharing the vehicles with other people. It is believed she was vomiting and had diarrhea while traveling. Contact with infected bodily fluids is one of the ways Ebola spreads.
When the WHO declared Liberia free of Ebola on Thursday, it marked the first time since the West African outbreak began in December 2013 that the world thought it was Ebola-free. In reality, that wasn’t the case.
The WHO had actually anticipated that, warning in its statement Thursday that small, survivor-fueled flare-ups would likely occur.
The West African Ebola outbreak, far and away the largest the world has ever seen, has led to more than 28,600 infections and more than 11,300 deaths.