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.