The World Health Organisation urged nations worldwide to help stop the spread of Ebola as it declared the outbreak in West Africa to be an international public health emergency.

Hopes of finding a treatment for the deadly ebola virus have shifted to a small California-based biotech company whose experimental drug has been used to treat two American missionary workers.

The husband of a second American aid worker recently diagnosed with Ebola has said his wife is weak but showing signs of improvement.

The second American aid worker recently diagnosed with Ebola in west Africa was en route to Atlanta today after a customs and refuelling stop in Maine.

The doctor who treated a man who flew to Nigeria and died of Ebola has now contracted the disease, authorities said.

Hundreds of troops have been deployed in Sierra Leone and Liberia under an emergency plan to fight the worst outbreak of the deadly ebola virus, which has killed more than 826 people across West Africa.

An American aid worker infected with the deadly ebola virus while in Liberia was being treated at an Atlanta hospital in a special isolation unit yesterday.