The World Health Organization said the deadly Ebola disease is spreading in the West African country of Gabon. The latest figures show a rise in the death toll to 13 with another six people suspected of having the virus.

The World Health Organization said at least 10 of the dead are from the same extended family. A health worker who treated the victims also has died. And WHO spokesman Gregory Hartl said one of the latest people to die was a nurse who treated the health worker.

Ebola is a highly contagious disease. But Mr. Hartl said health workers do not necessarily protect themselves because the symptoms are hard to distinguish from malaria. "When a person presents himself or herself to a hospital for treatment, the health care workers do not realize that they are dealing with Ebola and don't take the necessary precautions. The necessary precautions are basically in covering yourself from head to toe because if you touch a person's skin when they are suffering from Ebola and they are sweating, you can contract Ebola from the sweat or the perspiration of someone who is suffering," he said.

The Ebola virus is passed through contact with bodily fluids, including mucus, saliva and blood. It is not airborne. It incubates for four to 10 days before flu-like symptoms set in. There is no cure for the disease. But, the World Health Organization said chances of survival are pretty good if people are treated quickly with lots of fluids.

The disease outbreak is in Gabon's remote, northeastern jungles near the border with Congo-Brazzaville. Local authorities are restricting movements in and out of the region. But Mr. Hartl said there are reports of people leaving Gabon for the Congo. "It is natural for people to move around. So, we have seen this in any situation. In previous outbreaks, people move for a number of reasons. It might be social or economic reasons or indeed because there has been talk of an outbreak," he said.

Mr. Hart said an international team of experts is working with authorities in Gabon and Congo to try to trace anyone who may have had contact with any of the Ebola victims. He said special isolation units are being set up in hospitals for anyone suspected of carrying the virus.

This is the fourth outbreak of the disease in Gabon. The last time the Ebola struck the country, in 1996-97, it killed 45 of the 60 people infected.