Ebola has claimed more than 2,200 lives since December
The US is sending up to 3,000 troops to co-ordinate the response to the ebola outbreak in West Africa, as health experts warn it is “unparalleled in modern times”.
The virus has claimed more than 2,400 lives this year – mostly in Liberia, Sierra Leone and Guinea.
On a visit to the federal Centers for Disease Control and Prevention in Atlanta, Georgia, President Barack Obama is set to outline measures to prop up health services in areas overwhelmed by the epidemic.
Ahead of the announcement, unnamed administration officials revealed they would build 17 health care facilities in the region, each with 100 beds.
The US will attempt to train 500 medical staff a week, provide health kits to hundreds of thousands of homes and educate communities on how to tackle the problem.
The cost of the aid will be $500m (£308m), the officials said.
It is expected to take two weeks to get US personnel on the ground.
United Nations officials have warned the outbreak requires a $1bn response to keep its spread within “tens of thousands” of cases.
Speaking in Geneva, World Health Organisation Assistant Director General Bruce Aylward said: “Quite frankly, ladies and gentlemen, this health crisis we’re facing is unparalleled in modern times.
“We don’t know where the numbers are going on this.”
UN Secretary-General Ban Ki-moon will launch a “global response coalition” in New York on Thursday.
The virus, which has also reached Nigeria and Senegal, is spread through direct contact with the bodily fluids of sick patients. There is no vaccine or approved treatment.
Four Americans have been or are being treated for ebola in the US after evacuation from Africa.
The country’s intervention follows demands for a stepped-up international response.
The US ambassador to the United Nations, Samantha Power, has called for an emergency meeting of the Security Council, warning the virus could “set the countries of West Africa back a generation”.
US efforts will include medics and corpsmen, engineers to help build treatment facilities and logistics specialists to assist in patient transportation.