Health workers on the front line of the Ebola crisis say the need for urgent help continues, as the US 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 are still rising in other areas - and aid organizations say thousands of healthcare workers are needed to treat Ebola patients during 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 as well as 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.

Even if Obama were to give millions of dollars tomorrow, "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 was due to question Obama administration officials about the US response to the Ebola outbreak as it begins evaluating the emergency aid request, which includes $4.64 billion in immediate spending to fight the epidemic in West Africa, shore up US preparedness, and speed the development and testing of Ebola vaccines and treatments.

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

AP - AFP