Global medical charity Doctors Without Borders has warned the crisis is “unprecedented, absolutely out of control”.
“It is difficult to predict, because we have never known such an epidemic.”
The Peace Corps announced Wednesday that it was temporarily withdrawing its 340 volunteers in Guinea, Liberia and Sierra Leone after two workers were exposed to the Ebola virus.
A spokeswoman told CNN and CBS News that the pair were being isolated after coming in contact with an infected patient who later died. The two have not exhibited symptoms, however, and will be sent back the United States after doctors clear them.
The Peace Corps did not indicate when the volunteers might return to West Africa, where the growing outbreak is centered.
Health officials in the United Kingdom and Hong Kong, fearing that the outbreak of the deadly Ebola virus in West Africa could go global, have tested at least two airline passengers who have shown symptoms of the disease.
The outbreak — the largest in history — has spread across Guinea, Liberia, Nigeria and Sierra Leone and killed at least 672 people, according to the World Health Organization. The disease has no vaccine and no specific treatment. It has a fatality rate of at least 60%.
- Liberia will close schools and consider quarantining some communities, it said on Wednesday, announcing the toughest measures yet imposed by a West African government to halt the worst Ebola outbreak on record.
Security forces in Liberia were ordered to enforce the steps, part of an action plan that includes placing all non-essential government workers on 30-day compulsory leave.
Ebola has been blamed for 672 deaths in Liberia, neighboring Guinea and Sierra Leone, according to World Health Organisation figures, as under-funded healthcare systems have struggled to cope with the epidemic. Liberia accounted for just under one-fifth of those deaths.
"This is a major public health emergency. It's fierce, deadly and many of our countrymen are dying and we need to act to stop the spread," Lewis Brown, Liberia's information minister, told Reuters.
President Ellen Johnson Sirleaf said in a speech posted on the presidency's website that the government was considering quarantining several communities based on the recommendation of the health ministry.
Concern deepened last week when a Liberian-American died from Ebola in Nigeria having traveled from Liberia. Authorities in Nigeria, as well as Ghana and Togo, where he passed through en route to Lagos, are trying to trace passengers who were on the same plane as him.
Dozens of local health workers - including Sierra Leone and Liberia's top two Ebola doctors - have died treating patients. Two Americans working for Samaritan's Purse, a U.S. charity operating in Liberia, were infected over the past week.
Samaritan's Purse said on Wednesday that Kent Brantly, a doctor working for the charity, and Nancy Writebol, a colleague who was also volunteering in Liberia, had shown a slight improvement but their condition was still serious.