Disease

Ebola outbreak now most deadly ever in West Africa

 West Africa's first-ever Ebola outbreak in humans is now the most deadly and geographically widespread outbreak on record and is threatening to spread, health officials say.

According to the latest figures from the World Health Organization (WHO), there have been more than 635 cases of Ebola across three countries in the region since the outbreak was first declared in southeastern Guinea in March. It has since spread to Liberia and Sierra Leone. At least 400 people have died.

The virus, one of the world's most virulent, is transmitted by contact with the blood, fluids or tissues of infected animals or people. It causes high fever, vomiting, muscle pain and diarrhea, and can result in unstoppable internal bleeding and organ failure.

Transmission risk is especially high among doctors, nurses and other health care workers. There is no vaccine for it, nor any known cure.