LONDON — Facing the worst known outbreak of the Ebola virus, with almost 1,000 fatalities in West Africa, the World Health Organization declared an international public health emergency on Friday, demanding an extraordinary response — only the third such declaration of its kind since regulations permitting such alarms were adopted in 2007.
The organization stopped short of saying there should be general international travel or trade bans, but acknowledged that the outbreak, already in its sixth month, was far from being contained.
One major international medical organization, Doctors Without Borders, responded to the statement with a renewed call for a “massive deployment” of health specialists to the stricken countries. “Lives are being lost because the response is too slow,” it said.
Dr. Margaret F. C. Chan, the director general of the World Health Organization, a United Nations agency, told a news conference at its Geneva headquarters, “This is the largest, most severe, most complex outbreak in the nearly four-decade history of the disease.”
“I am declaring the current outbreak of the Ebola virus disease a public health emergency of international concern,” she said. “Countries affected to date simply don’t have the capacity to manage an outbreak on this scale on their own.”
Dr. Keiji Fukuda, head of health security for the health organization, said that “things will get worse for a while,” and that “we are fully prepared for addressing this for some months.”
The W.H.O. urged all nations where the disease is spreading to declare an emergency, to screen all people leaving at international airports, seaports and land crossings, and to prevent travel by anyone suspected of having the Ebola virus.
But the organization did not recommend a ban on travel to or from places with outbreaks because of the low risk of infection. “We don’t believe a general ban on that kind of travel makes any kind of sense at all,” Dr. Fukuda said.
The declaration was apparently intended to display a more aggressive stance by the health organization. In the past, it has often bent to pressure from member countries, demanding that there be no consequences even as epidemics have raged inside their borders and sometimes slipped over them.
“Declaring Ebola an international public health emergency shows how seriously W.H.O. is taking the current outbreak; but statements won’t save lives,” said Dr. Bart Janssens, the director of operations at Doctors Without Borders, which says it has hundreds of specialists in the field in West Africa. “It is clear the epidemic will not be contained without a massive deployment on the ground.”
According to figures released by the health organization on Friday, the virus is thought to have killed 961 people since March. Most of the cases are in Guinea, Liberia and Sierra Leone, but 13 cases have also been reported in Nigeria, including two deaths, after a person brought the disease there by plane from Liberia.