Scientists have predicted a 75 percent chance that the Ebola virus may reach France by Oct. 24 and a 50 percent chance that it could reach the UK by that date. The Ebola virus has so far affected 7,492 people in West Africa and has killed 3,439 people in the latest outbreak.

The predictions assume that air traffic will function at full capacity. However, considering that many airlines have reduced service to West Africa, France's risk of dealing with the virus would stand at 25 percent, while Britain's would be 15 percent, according to a study first published in the journal PLoS Current Outbreaks, and cited in a Reuters report. Belgium has a 40 percent chance of Ebola hitting its shores while Spain and Switzerland face a smaller chance -- 14 percent each -- of having to deal with an outbreak, according to the study.

"If this thing continues to rage on in West Africa and indeed gets worse, as some people have predicted, then it's only a matter of time before one of these cases ends up on a plane to Europe," Derek Gatherer, an expert on viruses from Lancaster University, said, according to Reuters.

While the U.S. is treating its first Ebola case amid fears of a mass outbreak in the country, Sierra Leone, one of the worst affected countries, recorded 121 deaths from the disease on Saturday, taking the total number of deaths in the country to 678 from 557 on the previous day, according to Reuters.

Meanwhile, an American doctor who had survived an Ebola infection, and is currently back in the hospital for cough and low fever, has not been affected by the virus again, hospital officials said Sunday. Massachusetts-based Rick Sacra was treated successfully for Ebola last month.

Sacra was admitted on Saturday to the UMass Memorial Medical Center and the hospital said that the results to test if the Ebola virus had resurfaced came back negative, according to Associated Press, or AP. The hospital had put him under observation and isolation as a precautionary step while waiting for results from the Centers for Disease Control and Prevention, or CDC, which confirmed Sunday that Sacra’s symptoms were not due to Ebola.

"People are very concerned, that's why we're being extremely cautious," Robert Finberg, head of Sacra's medical team, said, according to AP, adding: "We're not taking risks with Dr. Sacra and his caregivers."

Hospital spokesperson Peggy Thrappas reportedly said in a statement that Sacra would now receive routine care for an upper respiratory tract infection, and would be taken out of isolation. Sacra had contracted Ebola while working in Liberia and had returned to Massachusetts on Sept. 25, after being treated for the virus at a hospital in Omaha, Nebraska.

The U.S. is set to send a 4,000-member team to Liberia to help counter the spread of the disease, while the UK and China have already sent their teams to the region. Last week, Cuba sent a 165-member medical team to Sierra Leone.