Ebola cases first emerged in the nation of Guinea back in March, and later spread across the borders to Liberia and Sierra Leone.
The outbreak is now the largest recorded in world history, and has infected three African capitals with international airports. Officials are trying to step up screening of passengers, though an American man was able to fly from Liberia to Nigeria, where authorities say he died days later from Ebola.
Ebola has no vaccine and no specific treatment, with a fatality rate of about 60% in this particular outbreak. But experts say the risk of travellers contracting it is considered low because it requires direct contact with bodily fluids or secretions such as urine, blood, sweat or saliva. Ebola cannot be spread like flu through casual contact or breathing in the same air.
Patients are contagious only once the disease has progressed to the point they show symptoms, according to the World Health Organisation. The most vulnerable are health care workers and relatives who come in much closer contact with the sick.
