Dr. Tom Frieden, director of the Centers for Disease Control, listens while US President Barack Obama makes a statement to the press after a meeting in the Roosevelt Room of the White House October 6, 2014 in Washington, DC. Obama met with the national security team and senior staff on stopping the outbreak of Ebola. AFP PHOTO/Brendan SMIALOWSKI (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images) Dr. Tom Frieden, director of the Centers for Disease Control, listens while President Barack Obama makes a statement to the press after a meeting in the Roosevelt Room of the White House on Oct. 6, 2014 in Washington, D.C. (credit: BRENDAN SMIALOWSKI/AFP/Getty Images)

WASHINGTON (CBSDC/AP) — Health workers on the front line of the Ebola crisis say the need for urgent help isn’t letting up, as Congress begins considering President Barack Obama’s $6.2 billion emergency aid request to fight the disease.

Despite reports that the number of infections is slowing in some parts of West Africa, cases still are rising in other areas — and aid organizations say thousands of health care workers are needed to treat Ebola over the next few months.

“We’re not yet at a point where we can have confidence that we’re turning the corner, even in Liberia,” said Andy Gleadle of the International Medical Corps, which is running a treatment center in Liberia and plans to open another in that country and two more in Sierra Leone.

Even with increasing global attention to the epidemic, it takes time to train new health workers, build field hospitals, and buy protective equipment for doctors and nurses.

“Let’s say President Obama gives us another $5 million tomorrow morning — which would be very nice, thank you — but it takes weeks to absorb that funding and implement it on the ground,” added Gleadle, who is responsible for the charity’s response in Sierra Leone.

On Wednesday, the Senate Appropriations Committee is set to question Obama administration officials about the U.S. response to the Ebola outbreak as it begins evaluating the emergency aid request. It includes $4.64 billion in immediate spending to fight the epidemic in West Africa, shore up U.S. preparedness, and speed the development and testing of Ebola vaccines and treatments.

More than $1.5 billion would be for a contingency fund to deal with any unexpected developments.

“The situation does change quite dramatically from one day to the next, one week to the next,” Dr. Tom Frieden, director of the Centers for Disease Control and Prevention, told The Associated Press.

Cases continue to pop up in new areas across the three hard-hit West African countries of Liberia, Sierra Leone and Guinea, he said.

“The challenges are really daunting, and one of the critical needs is for speed and flexibility” as those clusters emerge, Frieden said.

The hearing comes even as Ebola is fading from U.S. headlines.

The last Ebola patient being treated in the U.S. — a doctor who was diagnosed after returning from a volunteer stint fighting the virus in Guinea — was released from a New York City hospital Tuesday. His fiancee remains in quarantine at their apartment, and New York officials continue to monitor health workers who cared for him as well as other recent travelers from West Africa.

That “doesn’t mean we’re out of the woods,” Frieden cautioned. Until the epidemic is ended in West Africa, “there is still the real possibility that other people with Ebola will be diagnosed in the U.S.”

There’s bipartisan concern about Ebola and its threat to the U.S., and support for military and public health efforts at fighting the epidemic in West Africa. But Republicans have been critical of the Obama administration’s security measures at home and how it has helped states and hospitals prepare for cases since Liberian visitor Thomas Eric Duncan became the first Ebola patient diagnosed in the U.S. He died in Dallas; two nurses who treated him became infected but recovered.

Nearly 5,000 people have died during the Ebola outbreak.

Sen. Chris Coons of Delaware, a Democrat on the Appropriations Committee, said he’s optimistic the spending package will pass quickly, and hopes it won’t get delayed by debate over such things as travel bans.

“We need to keep on this task and to keep supporting” the military, government health workers and volunteers abroad while at the same time “making sure the United States has the resources and preparation and ability to keep us safe at home,” he said.

Among the proposed spending:

—$1.83 billion for the CDC, to be divided between fighting the epidemic in West Africa, ramping up U.S. preparedness and global health security — helping other vulnerable countries build the health systems and train their workers to spot and respond to early signs of outbreaks.

—On the domestic front, the CDC would support more than 50 hospitals around the country designated as being capable of safely treating Ebola cases, train health workers and health departments how to screen for Ebola and handle suspect and confirmed cases, and buy protective equipment for the national stockpile.

—Also included is $238 million for the National Institutes of Health for clinical trials of experimental vaccines and treatments.

—The U.S. Agency for International Development and State Department would receive about $2 billion to further scale up assistance in West Africa.

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