New rules will come into effect in the United States today for people travelling from west African nations hit hardest by Ebola.

Those arriving from Guinea, Liberia or Sierra Leone will have to fly through the five US airports already screening passengers for the disease - New York’s JFK, Newark, Dulles, Atlanta and Chicago.

In a statement, Secretary of Homeland Security Jeh Johnson explained, "we are working closely with the airlines to implement these restrictions with minimal travel disruption. If not already handled by the airlines, the few impacted travelers should contact the airlines for rebooking, as needed.

"We currently have in place measures to identify and screen anyone at all land, sea and air ports of entry into the United States who we have reason to believe has been present in Liberia, Sierra Leone or Guinea in the preceding 21 days," he added.

It is not a travel ban, which Barack Obama has been opposing.

However, White House spokesman Josh Earnest says the president supports some measures being put in place, like this one:

Meanwhile, a US photojournalist says he is grateful to be alive after the hospital treating him declared him free of Ebola.

Ashoka Mukpo was working as a freelance cameraman for NBC News in Liberia when he fell ill.

He is expected to go home from hospital in Nebraska later today.