WASHINGTON (Thomson Reuters Foundation) - A shortage of volunteers to staff the new Ebola clinics and hospitals the international community is building in West Africa threatens efforts to bring the deadly virus rapidly under control, aid agencies have warned.

Health workers bring a woman suspected of having contracted Ebola virus to an ambulance in front of a crowd in Monrovia, Liberia, September 15, 2014. REUTERS/James Giahyue

“The missing link is staff,” Athalia Christie, deputy for global health at the Centers for Disease Control and Prevention, who has just returned from Liberia, told the Thomson Reuters Foundation.

The United States this week announced it will send in its military to build 17 Ebola treatment centers in Liberia. Army engineers from Britain are building a 200-bed hospital in Sierra Leone, while the United Nations has formed a special mission to lead efforts.

This marks a dramatic scaling up of the global response to the Ebola crisis, which has claimed over 2,500 lives this year - mostly in Liberia, Sierra Leone and Guinea where infections are spiraling out of control as healthcare systems collapse.

When world leaders meet for the United Nations General Assembly in New York next week, their sessions will include a two-day summit on the Ebola crisis.

Many questions remain over how to handle the deadly virus. Medical experts have yet to agree on a basic method of treatment, which shapes the types of aid that will be delivered. More money is needed, as well as more people to work in the region and more training.

Experts at a poverty conference run by the U.S. development agency USAID in Washington on Friday said recruiting staff must be a top priority.

Each 100-bed Ebola treatment center under construction needs 230 trained staff, including 12 medical experts, to operate, U.S. officials said. That would mean nearly 4,000 personnel for the Liberian facilities due to start opening in October, and it is unclear where they will come from.

“Building hospitals and equipping them is great. But unless you have trained personnel to work in them, that is not going to help,” said Rabih Torbay, senior vice president at the global healthcare nonprofit International Medical Corps (IMC).

“Seventeen thousand beds, but who is going to staff them?” asked Torbay, who leads IMC’s Ebola response.

‘TERRIFIED’

Usually humanitarian groups are inundated with volunteers ready to fly into disaster zones after earthquakes or floods. But Ebola has terrified people, he said.

It spreads rapidly through contact with sweat, saliva, blood and other bodily fluids of an infected person, and the average death rate is over 50 percent.

The epidemic has overwhelmed Liberia, Sierra Leone and Guinea, which had a critical shortage of doctors and nurses even before the Ebola outbreak, which began earlier this year. Infections are estimated at 5,000, though the actual rate may be two or three times larger since many people are hiding in their homes.

The World Health Organization says the infection rate is doubling every 10 to 21 days, which means hospitals and clinics may not be built and staffed fast enough to meet demand.

U.S. officials are recruiting healthcare personnel from universities and hospitals, said Torbay. China has pledged doctors and nurses, and the African Union is sending a team of 30 health workers and specialists to the region.

But the task of training them is huge, said Christie. They require seven to 10 days of classroom and practical work before they can enter hospitals and clinics. Relief staff must replace them every four to six weeks because workers get exhausted - emotionally from the high death toll and physically from wearing five layers of protective gear in extreme heat.

Nancy Lindborg, USAID assistant administrator, said international agencies have drawn up a detailed matrix, specifying what each country and organization can contribute to addressing the Ebola crisis.

“Health workers is the key gap,” she said.