Hundreds of blood samples are being analysed to keep track of the virus.
Scientists tracking the Ebola outbreak in Guinea say the virus has mutated.Researchers at the Institut Pasteur in France, which first identified the outbreak last March, are investigating whether it could have become more contagious.
More than 22,000 people have been infected with Ebola and 8,795 have died in Guinea, Sierra Leone and Liberia.
Scientists are starting to analyse hundreds of blood samples from Ebola patients in Guinea.
They are tracking how the virus is changing and trying to establish whether it's able to jump more easily from person to person
"We know the virus is changing quite a lot," said human geneticist Dr Anavaj Sakuntabhai.
"We've now seen several cases that don't have any symptoms at all, asymptomatic cases," said Anavaj Sakuntabhai.
"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 less deadly, but more contagious and that's something we are afraid of."
But Professor Jonathan Ball, a virologist at the University of Nottingham, says it's still unclear whether more people are actually not showing symptoms in this outbreak compared with previous ones.
"We know asymptomatic infections occur… but whether we are seeing more of it in the current outbreak is difficult to ascertain," he said.
"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."
Another common concern is that while the virus has more time and more "hosts" to develop in, Ebola could mutate and eventually become airborne.
There is no evidence to suggest that is happening, however. The virus is still only passed through direct contact with infected people's body fluids.
"At the moment, not enough has been done in terms of the evolution of the virus both geographically and in the human body, so we have to learn more. But something has shown that there are mutations," said Institut Pasteur virologist Noel Tordo.
"For the moment the way of transmission is still the same. You just have to avoid contact (with a sick person)"
"But as a scientist you can't predict it won't change. Maybe it will."
Researchers are using a method called genetic sequencing to track changes in the genetic make-up of the virus. So far they have analysed around 20 blood samples from Guinea. Another 600 samples are being sent to the labs in the coming months.
A previous similar study in Sierra Leone showed the Ebola virus mutated considerably in the first 24 days of the outbreak, according to the World Health Organization.
It said: "This certainly does raise a lot of scientific questions about transmissibility, response to vaccines and drugs, use of convalescent plasma.
"However, many gene mutations may not have any impact on how the virus responds to drugs or behaves in human populations."