Ebola: Ground Zero

Can you give us an overview of this outbreak so far?

The outbreak started in the village of Meliandou in eastern Guinea in December 2013 before spreading to the local hospital in Macenta, and then onto the larger town of Gueckedou. A doctor who died in Gueckedou had his funeral in his home town of Kissidougou, where family members were infected. Somebody from Gueckedou went on a commercial trip to Dabola, further north, and died there. He stayed in the same hotel as a man from Dinguiraye in the extreme north of Guinea, who was travelling to the capital Conakry. The man from Dinguiraye then took the virus to the capital. Within 3 months of the start of the outbreak, the Ebola virus was in its first large urban outbreak. Conakry has 124 confirmed cases at the time of writing this – 17% of all the cases in Guinea.

In Liberia it was a similar story. A Liberian woman who had been to a market in Gueckedou became sick on her return to Foya in northern Liberia. She died in Foya. Her sister began to feel unwell and decided to go and see her husband in the Firestone Rubber Plantation where he worked, which required an overnight communal taxi ride to Monrovia. Most of the people who shared the taxi subsequently caught the disease. She then hitched a ride up to Firestone on a motorcycle, despite being seriously ill by that time, and reached her husband before she died. The motorcycle rider has never been found.

In Sierra Leone, it seems that a doctor who had been working in Guinea hitched a lift on a truck headed west into Sierra Leone. The doctor got off at a town called Jawie in Kailahun province, and the first cases appeared there. The truck driver then went on to Mambolo, north of the capital Freetown. A second entry point may have been from Guinea to another central Sierran town called Kakua. 63% of Sierra Leone’s cases are in the provinces of Kailahun and neighbouring Kenema.

By 14th September, there were a total of 6346 cases across West Africa, of which 5398 had been confirmed as ebolavirus, with 3079 deaths.

Previous outbreaks of Ebola have been confined to a few hundred people – what’s different this time?

The case fatality rate of just under 50% is less than the usual 80% seen for previous outbreaks of Zaire ebolavirus. Additionally, epidemiological modelling has suggested that the virus is perhaps a little less infectious than in previous outbreaks. So the alarming spread of this outbreak – over 13 times bigger than any previous one – is not due to a new aggressive virus strain, because the evidence points the other way, but rather due to the fact that it was not recognised that ebolavirus had broken out until we had several dozen dispersed cases, including some in urban locations. The fact that ebolavirus has not previously appeared in this region meant that people simply assumed it was something else, like Lassa fever, and the outbreak was not really picked up until it had been going for 3 months, by which time it had already made the leap to Conakry.

How have previous Ebola outbreaks been contained?

As Medicins Sans Frontieres say, “with soap and education”. Quarantine is important too. In previous outbreaks, cordons sanitaires were used around villages. Now the Liberian and Sierra Leone governments are trying to cordon off whole provinces, which is much harder to do effectively. Sierra Leone is in the middle of a 3-day lockdown across the whole country. It will be interesting to see if it helps. These are desperate measures and many are sceptical. However, in the middle of an unprecedented situation, we have no previous experience to guide us.

Why is developing a vaccine or treatment for Ebola proving so difficult?

It’s always difficult for viruses. We have scarcely a good anti-viral in the medicine chest. They are so small in terms of genome size that they present very little in the way of drug targets. Some, like Ebola, target the immune system as part of their natural pathogenesis. Vaccination is always difficult against small RNA viruses as they evolve so quickly.

How do you expect the outbreak to develop?

I think we are in for a long haul. The prospect of Ebola becoming an endemic disease is very real, which would have serious economic and social consequences for West Africa. It might also spread locally to neighbouring African countries. WHO also believe that the real disease totals are far higher than the official figures. Assuming official figures are broadly correct, we can expect 20-40,000 cases by the New Year. Current rates of increase of case numbers are at 7% per week. Although we are likely to get some cases arriving here in the EU, they will be picked up on arrival. I don’t think that there is any real worry about spread in Europe or North America.