Head of medical aid group Doctors Without Borders calls for more leadership from the World Health Organization to bring the Ebola epidemic in West Africa under control. (Reuters)

There have been 1,069 deaths attributed to Ebola so far, but the true toll of the virus could be far greater, the World Health Organization said on Thursday.

"Staff at the outbreak sites see evidence that the numbers of reported cases and deaths vastly underestimate the magnitude of the outbreak," the organization said in a release.

It could be many more months before the outbreak, which has primarily afflicted three West African Nations, Guinea, Liberia and Sierra Leone, can be brought under control.

In Nigeria, four people have died from Ebola. But thanks to extensive contact tracing and monitoring of potential patients, there have been no new reported cases since the disease spread through a sick traveler who arrived in the country.

Experts fear that there are many unreported deaths and undiagnosed cases that not only mask the true impact of the virus, but make it more difficult to bring the outbreak under control.

"Elsewhere, the outbreak is expected to continue for some time. WHO’s operational response plan extends over the next several months," the organization said.

The head of Doctors Without Borders, which runs treatment facilities in Guinea, Liberia and Sierra Leone, believes that it could take up to six months.

"Over the next six months, we should get the upper hand on the epidemic, this is my gut feeling," Joanne Liu, international president of Doctors Without Borders, said in a news conference in Geneva, according to Reuters.

The organization is particularly concerned about the spread of Ebola in Liberia, where its toll has been "catastrophic."

"If we don't stabilize Liberia, we will never stabilize the region," Liu said, according to Reuters.

Despite the fact that there are no suspected cases among the athletes, Ebola fears have caused the International Olympic Committee (IOC) to ban three West Africans who compete in combat and pool events at the upcoming Youth Olympics games in China this weekend as a precaution. Ebola is spread through contact with bodily fluids of an infected person.

"We have been reassured by the health authorities that there have been no suspected cases and that the risk of infection is extremely unlikely," the IOC statement said. But, it said it could not completely rule out the risk of infection, particularly in pool sports.

"We regret that due to this issue some young athletes may have suffered twice, both from the anguish caused by the outbreak in their home countries and by not being able to compete in the Youth Olympic Games," the IOC added.