A controversial decision to impose Ebola quarantines in three US states is sparking criticism it will discourage badly needed health workers from volunteering in the crisis in West Africa.
More than 4,900 people have died in the worst ever outbreak of the hemorrhagic virus, most in Guinea, Liberia and Sierra Leone.
Strict new rules in New York, New Jersey and Illinois requires a three-week quarantine, because symptoms of the disease can develop any time within that period after exposure.
But health authorities say this measure is unnecessarily strict and could be counterproductive. Still, on Sunday two governors, Andrew M. Cuomo of New York and Chris Christie of New Jersey, stood by their decision, saying that the federal guidelines did not go far enough.
"The best way to protect us is to stop (the outbreak) in Africa, and one of the best ways to stop it in Africa is to get health workers who are going there and helping them with their problem," National Institute of Allergy and Infectious Diseases director Anthony Fauci told CNN Sunday.
But "when they come back, they need to be treated in a way that doesn't disincentivize them from going there," he said, speaking on CNN's State of the Union talk show.
Fauci stressed that the scientific evidence "tells us people who are not ill, who don't have symptoms, with whom you don't come into contact with body fluids, they are not a threat, they are not going to spread it."
But New Jersey Governor Chris Christie defended his state's mandatory quarantine, calling it necessary "to protect the public health of the people of New Jersey."
Speaking on Fox News Sunday, Christie said: "I think this is a policy that will become a national policy sooner rather than later."
He rejected arguments it would discourage health workers from traveling to the most impacted zone to help, saying "I believe that folks who want to take that step, willing to volunteer, also understand it's in their interests and the public health interests to have a 21-day" quarantine.
New York, New Jersey and Illinois ordered the mandatory measure on Friday.
New Jersey has already isolated a nurse who arrived at Newark with a recent history of treating patients with Ebola in West Africa, but who has tested negative for the virus.
Kaci Hickox, in an account in the Dallas Morning News, complained she was made to feel "like a criminal" and said she was "scared for those who will follow me."