New Ebola cases fall most in week since June

The number of new Ebola cases in the three most affected countries rose at its slowest weekly pace since June, the World Health Organization said Thursday.

A total of 99 new, confirmed incidents of the virus were reported in Guinea, Liberia and Sierra Leone in the week to Jan. 25, WHO said. That is the first time since last year that new cases on a weekly basis fell below 100.

Guinea reported 30 new cases, Liberia saw 4 new cases and there were 65 new instances of the disease in Sierra Leone for the period in question.

The three West African countries have a total of 22,000 confirmed, probable or suspected cases of Ebola and at least 8,795 have died from the virus there.

Mali, Nigeria, Senegal, Spain, the United Kingdom and the United States have also had confirmed cases of Ebola, but the vast majority of the 22,092 cases and 8,810 deaths have occurred in West Africa, where the WHO continues to describe the transmission rate as "widespread and intense."

The relatively positive development nonetheless comes as scientists tracking Ebola warned this week that the virus has mutated.

Anavaj Sakuntabhai, a geneticist at the Institut Pasteur in France, told BBC radio on Thursday that several cases of Ebola have now been seen where the infected person does not appear to have any symptoms.

"These people may be the ones who could spread the virus better, we do not know yet," Sakuntabhai said. "A virus can change from more deadly into less deadly but more contagious and that is something we are afraid of."