According to the World Health Organisation (WHO), two weeks ago in January, between the 18th and the 25th, there were fewer than 100 reported cases of Ebola in the three most-affected countries in Africa. With 30 reported cases in Guinea, four in Liberia and 65 in Sierra Leone, it's the first time since late June 2014 that the number of reported cases have been that low, which suggests that the outbreak is finally on the decline.

And now, scientists in France are analysing the strain to discover that it's mutating, but no one really knows what the end result will look like.

The team, based at the Institut Pasteur, has so far analysed 20 blood samples from Ebola patients in Guinea, and have another 600 on their way. By tracking changes in the genetic make-up of the virus, they can see how the virus is changing over time, noting that the worst case scenario wouldn't be that the virus is mutating to become more deadly, but that it's becoming more contagious, and difficult to detect. The more time spent living inside a host without being detected and thwarted with medical treatment, the more chance the virus will have to undergo advantageous mutations.

"We know the virus is changing quite a lot," one of the team, geneticist Anavaj Sakuntabhai, told Tulip Mazumdar at BBC News. "We've now seen several cases that don't have any symptoms at all, asymptomatic cases. These people may be the people who can spread the virus better, but we still don't know that yet. A virus can change itself to [be] less deadly, but more contagious, and that's something we are afraid of."

The results correlate to those of a similar study, carried out by a separate team of researchers in Sierra Leone last year, showing that the virus underwent several significant changes during the first 24 days of the 2014 outbreak. 

It's not unusual for a virus to mutate - as Rob Brooks from the Evolution & Ecology Research Centre at the University of New South Wales in Australia says, it's what viruses do - but it's often very tough to predict what this could mean for future infections. Recent reports from hospitals in Africa have shown that a bunch of new cases are cropping up where the patient isn't exhibiting any symptoms, which could mean the virus is becoming more contagious and less deadly, but early results from the blood sample analysis have so far shown no evidence of the virus changing its mode of transmission. 

"We know asymptomatic infections occur… but whether we are seeing more of it in the current outbreak is difficult to ascertain," Jonathan Ball, a virologist at the University of Nottingham in the UK, who was not involved in the study, told the BBC. "It could simply be a numbers game, that the more infection there is out in the wider population, then obviously the more asymptomatic infections we are going to see."

The team at the Institut Pasteur are currently working on two different vaccines for Ebola, for which human trials are planned later this year. It's hoped that understanding the virus's many nuances on a genetic level will give them the upper hand in fighting it.

"This particular outbreak may wane and go away, but we're going to have another infectious outbreak at some point, because the places where the virus hides in nature, for example in small animals, is still a threat for humans in the future," one of the team, immunologist James Di Santo, told BBC News. "The best type of response we can think of… is to have vaccination of global populations."

Source: BBC News