The world’s epidemic watchers are holding their breath this week. The latest Ebola outbreak in the Democratic Republic of the Congo seems to be subsiding, after . But Tedros Ghebreyesus, head of the World Health Organization, has warned that the coming days will be critical.
That is partly because the outbreak is in North Kivu province in the war-torn northeast of the DRC, where fighting by more than 50 armed groups puts many areas off limits.
To stop the virus spreading, medical teams must isolate and vaccinate anyone who has had contact with an infected person, and do the same for all the people they in turn contacted. But, says the WHO, the teams can’t work much more than 30 kilometres from the epidemic’s centre in Beni.
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Worse, the UN’s has found that people in the region are highly mobile, with traders and miners transiting to Uganda and Rwanda, and a million displaced by violence.
Such high population mobility, plus a slow medical response, caused a local Ebola outbreak in West Africa to mushroom into an unprecedented epidemic that killed more than 11,000 in 2014.
Fast response
This time the response has not been slow. The outbreak was recognised on 1 August, only a week after an Ebola epidemic on the other side of the DRC had been halted. A week later teams in North Kivu were vaccinating contacts.
This selective “ring vaccination” of the contacts of known cases, then their contacts, makes best use of limited vaccine stocks by containing virus spreading from known cases.
It seems to be working: on 1 September, with 5462 contacts vaccinated, WHO reported 13 new cases the previous week, down from 25 the week before, and 35 the week before that.
If that continues, the 300,000 doses of vaccine available worldwide should be more than enough to contain this epidemic. But epidemics can hit tipping points and soar exponentially. Stopping that requires stopping all the chains of transmission, says Mike Ryan, head of emergency response at the WHO.
Invisible virus
Moreover, Ebola epidemics come in waves: the next surge could still be incubating, or invisible in violent no-go areas. Worryingly, four of the new cases reported last week were not from known chains of transmission, meaning there are unknown chains out there.
They may be hard to find. The IOM has used its data to choose the 34 most important transport hubs where people leave the region, and Congolese authorities have so far checked 840,000 travellers there for symptoms.
It has also mapped highly vulnerable spots, such as popular markets and churches with strong connections to the outbreak zone, for closer monitoring.
But the IOM is only able to monitor relatively safe zones. “The news of two confirmed cases in Oicha is extremely distressing, because the area is almost entirely surrounded by armed militants,” says Michelle Gayer of the US-based .
Last week a medical team with a heavy UN military escort vaccinated 97 contacts of two cases in Oicha, discovered only because one travelled to Beni. Anyone in the area around Oicha cannot be reached.
And another large group is not being vaccinated: pregnant and lactating women. The Ebola vaccine consists of a harmless live virus that carries an Ebola protein. Pregnant women are normally not given live vaccines until risks to the foetus are tested.
A recent editorial by Ruth Karon of Johns Hopkins Medical School and colleagues that the very high death rates of pregnant women and foetuses from Ebola makes it nonsense to deny them vaccine for such hypothetical risks – while as carers they also spread the virus.
Experimental drugs
Last week the WHO decided to test three antiviral drugs in randomly chosen patients. No one will get a placebo, so the trials can’t establish formally how much better the drugs are than getting no drug. But they can compare the three.
Two people have received ZMapp, a cocktail of antibodies, the immune proteins that attack the Ebola virus. It showed promise in 2014, but is hard to administer and must be kept at minus 80°C, difficult in the DRC. Five have got , a small molecule that blocks the infection process.
The real surprise is that 13 have got mAb114, an antibody from a survivor of the 1995 Ebola epidemic in Kikwit, DRC, which can be kept in a refrigerator and needs only one simple injection.
Last year a WHO panel judged it too untested to try during epidemics, but the US National Institutes of Health has since rushed through safety trials in humans. Two people on it have recovered, says the WHO, though it is too soon to say if the drug helped.
