Story highlights Bill and Melinda Gates Foundation joins fight of Ebola outbreak in West Africa

More than 2,200 people have died in Guinea, Liberia and Sierra Leone

Money will be used to purchase supplies and scale up emergency operations

The Bill and Melinda Gates Foundation announced Wednesday it will donate $50 million to help fight the Ebola outbreak in West Africa.

More than 2,200 people have died in Guinea, Liberia and Sierra Leone, where the outbreak has been concentrated. Cases have also been reported in nearby Nigeria and Senegal.

The foundation says the money will be used to enable international aid organizations and national governments "to purchase badly needed supplies and scale up emergency operations in affected countries."

It will also "work with public and private sector partners to accelerate the development of therapies, vaccines, and diagnostics that could be effective in treating patients and preventing further transmission of the disease."

The first human trial of an experimental Ebola vaccine began last week at the National Institutes of Health.

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This is considered the deadliest Ebola outbreak in history. The World Health Organization said Monday the rapid spread of the virus in Liberia shows no sign of slowing.

"The number of new cases is increasing exponentially," WHO said, calling the situation a "dire emergency with ... unprecedented dimensions of human suffering."

Taxis packed with families who fear they've contracted the deadly virus criss-cross the Liberian capital, searching for a place where they can be treated, WHO said. But there are no available beds.

"As soon as a new Ebola treatment facility is opened, it immediately fills to overflowing with patients," the U.N. group said.

To help ease some of the burden on West Africa's already over-taxed medical system, the United States announced Tuesday it will send $10 million in additional funds. That's in addition to the $100 million Washington has already sent to help fight the outbreak. USAID also announced it will make $75 million in extra funds available.

The new funds will pay for transportation and support to send 100 more health care workers to help fight the epidemic. The WHO and several nonprofit agencies on the ground have repeatedly called for the international community to send additional trained help.

USAID funding has already provided 130,000 sets of personal protective equipment, 50,000 hygiene kits, and 1,000 new beds.

USAID has created a website where trained nurses, physician assistants or doctors who want to help can sign up.

On Sunday, President Barack Obama said the Ebola outbreak needs to be a " national security priority ." Obama told NBC's "Meet the Press" that the U.S. military could help set up isolation units and provide security for public health workers.

"If we don't make that effort now, and this spreads not just through Africa but other parts of the world, there's the prospect then that the virus mutates. It becomes more easily transmittable. And then it could be a serious danger to the United States," he said.