Ebola reaches Nigeria, and a puzzle over how it got there
Africa's most populous country confirmed its first case of the Bundibugyo epidemic, as Kenya recorded a second death and the first trial of a vaccine began in Congo.
The Ebola epidemic that began in the Democratic Republic of the Congo in May reached West Africa this week. On Tuesday 20th October Nigeria, Africa's most populous country, confirmed its first case: a woman in the capital, Abuja, who had travelled from Uganda.1
It is a single case, and Nigeria's health minister, Muhammad Ali Pate, called it "a contained single case".2 What worries health officials is that nobody yet agrees how she was infected.
One case, 44 contacts
According to the World Health Organization's office for Africa, the woman developed symptoms on 7th October, four days after arriving in Nigeria. She went to a private clinic in Abuja on 11th October, and laboratory tests confirmed Ebola on 20th October. Forty-four people who had contact with her are being monitored.1
The disease is caused by the Bundibugyo virus, one of several species of Ebola virus. It is named after Uganda's Bundibugyo district, where an outbreak in 2007 led to its discovery.3 There is no licensed vaccine or treatment for it.4 The vaccine used against earlier Ebola epidemics, Ervebo, was made for a different species.5
Where did she catch it?
Three accounts emerged in three days. Uganda's health ministry said the woman was a Nigerian businesswoman who had been to eastern Congo and only passed through Uganda: "Travel through Uganda does not establish that infection occurred here."6 On 23rd October the Swiss foreign ministry said she was the Ugandan-born wife of a Swiss diplomat in Abuja, had not been to Congo, and was believed to have been infected while travelling with her husband in Uganda. A Ugandan government spokesman called that suggestion "preposterous".7
The Africa Centres for Disease Control and Prevention, or Africa CDC, pointed to a coincidence: the woman and Kenya's first Ebola patient both left Uganda's Entebbe airport on 3rd October.7 Marion Koopmans, a Dutch virologist on the WHO's Ebola emergency committee, was sceptical: "Random presence at the same location, a large airport, is not a supported epidemiological link by any standard of what we currently know."7
Then, on 23rd October, Pate said genetic sequencing showed that Nigeria's virus was "closely related to the strain detected in Kenya's index case".8 That is the first genetic link between the two, but it does not show where either person was infected. Uganda, which had 20 cases earlier this year and declared its own outbreak over in August,9 announced on Friday that people who had travelled to Congo could no longer transit the country.10
Kenya's cluster
Kenya's cases all trace back to one man, who travelled from Congo by road through Uganda, flew to Nairobi on 3rd October and died there two days later.4 By 20th October Kenya had nine confirmed cases, all of them his relatives or the health and care workers who treated him.4 On 23rd October the health ministry announced a second death,11 a 65-year-old woman who was a close relative of the first patient. "All cases remain within one cluster of known contacts, and there is no evidence of community spread," it said.12
The scale in Congo
The cases outside Congo are a tiny part of the epidemic. By 20th October Congo had recorded 9,704 confirmed cases and 4,687 deaths, most of them in Ituri province, according to the WHO.4 To put that in context, it is the second-deadliest Ebola epidemic on record, after the West African epidemic of 2014 to 2016, in which more than 11,000 people died.7 The WHO declared it a public health emergency of international concern on 17th May.13
On 23rd October the first volunteer was vaccinated in Bunia, the main city of Ituri, in a trial that will test Ervebo first and then candidate vaccines made specifically for Bundibugyo.5 "There is still no licensed vaccine against Bundibugyo virus, and the cost of that absence is being counted in the DRC every day," said Richard Hatchett, chief executive of the Coalition for Epidemic Preparedness Innovations, or CEPI, which helps fund it.5
What remains open
Nigeria's 44 contacts are still being watched, and the WHO says it is revising its assessment of the risk to the region.4 Until investigators establish where the Abuja patient was infected, they cannot rule out a chain of transmission that nobody has yet found.