The World Health Organisation on Friday declared the Ebola outbreak that is spreading across West Africa to be a "public health emergency of international concern."
WHO chief Dr. Margaret Chan said the announcement is "a clear call for international solidarity" but also said many countries would probably not see any Ebola cases.
"Countries affected to date simply do not have the capacity to manage an outbreak of this size and complexity on their own," Chan said. "I urge the international community to provide this support on the most urgent basis possible."
Chan spoke to journalists at a news conference in Geneva.
The WHO declared similar emergencies for the swine flu pandemic in 2009 and for polio in May.
The Centers for Disease Control and Prevention in the USA has already elevated its Ebola response to the highest level and has recommended against traveling to West Africa.
The Ebola outbreak — the largest and longest in history — has so far killed 932 people and sickened more than 1,700 others.
There is currently no licensed vaccine or treatment for Ebola although experimental drugs are being explored after two American medical missionaries infected with the virus appeared to show signs of improvement after taking new medications.
Around 50% of people who have been infected in this latest outbreak have died from the virus.
The epidemic has affected Guinea, Liberia, Nigeria, and Sierra Leone.
The WHO made a number of recommendations Friday for countries looking to stop transmission of the disease, for states with potential cases and for states that are not currently affected but are seeking to reduce the risk of exposure.
One of the recommendations from the WHO is that there "should be no general ban on international travel or trade" to the affected nations. However, the WHO also said the "general public should be provided with accurate and relevant information on the Ebola outbreak and measures to reduce" exposure.
"States should be prepared to facilitate the evacuation and repatriation of nationals (e.g. health workers) who have been exposed to Ebola," the WHO said.