US health officials will actively monitor health workers who have treated Ebola patients in West Africa, under new rules.
Updated guidelines issued on Monday will require most medics to be checked for symptoms for 21 days but will not require quarantine or isolation.
The UN Secretary General has condemned enforced quarantine measures.
The current Ebola outbreak in West Africa has infected more than 10,000 people and killed almost 5,000.
The US announcement comes after a nurse who complained about her quarantine in New Jersey was allowed to return home.
Defying the new guidelines, New Jersey Governor Chris Christie defended the mandatory isolation imposed on Kaci Hickox as she returned home from Sierra Leone. He added: “That’s what we will continue to do.
His stance conflicts with UN Secretary General Ban Ki-moon, who earlier said those seeking to help in affected areas “should not be subjected to restrictions that are not based on science”.
“Those who develop infections should be supported, not stigmatised.”
People are not contagious until they develop Ebola symptoms.
In other developments:
- the US Army Chief of Staff has imposed a 21-day monitoring period for all soldiers returning from the region
- the husband of a Spanish nurse who recovered from Ebola has been sharply critical of Spain’s government
- the UN’s chief of Ebola mission has told the BBC the outbreak is likely to get worse
- a five-year-old boy has tested negative for Ebola in New York after visiting West Africa and developing a fever
- in the US, the Pentagon says about a dozen US troops returning from West Africa are being isolated at a base in Italy.
The new rules to allow monitoring of at-risk people were announced as concern grew over the treatment of those who had travelled to Ebola areas.
Three US states including New Jersey had said they would require a 21-day quarantine for all health workers who have had contact with Ebola patients.
The move came in response to a New York doctor who fell ill with the Ebola virus last week, the morning after he had travelled on the subway and been bowling.
On Monday, the US Centers for Disease Control and Prevention (CDC) issued fresh guidance for travellers and health workers returning from West Africa, where the outbreak has claimed more than 4,000 lives.
It set out four risk categories, and put most healthcare workers returning from the epidemic-hit region as at “some risk” of infection.
CDC director Dr Tom Frieden said workers considered to be at high risk or some risk would be required to be “actively” monitored for symptoms for 21 days.
Those at highest risk are anyone who’s had direct contact with an Ebola patient’s body fluids.
Even if they have no symptoms, they should avoid commercial travel and large public events, Dr Frieden said, adding that voluntary quarantine was enough.
Ms Hickox said she was made to feel like a criminal after being quarantined in Newark as she returned from Sierra Leone last Friday.
She was released on Monday and flown back to her home in Maine.
The New Jersey health department said Ms Hickox had tested negative for Ebola on Saturday and had been free of symptoms for 24 hours.
Mr Christie defended his state’s quarantine procedures and said that Ms Hickox had arrived in the US with a temperature – something the nurse denies.
“She’s a good person and went over and was doing good work over in West Africa. But she needs to understand that the obligation of elected officials is to protect the public health of all the people,” Mr Christie told reporters on Monday.
“And if that inconvenienced her for a period of time, that’s what we need to do to protect the public.”
More than 10,000 people have contracted the Ebola virus, with 4,922 deaths, according to the World Health Organization’s latest figures.
All but 27 of the cases have occurred inside Sierra Leone, Liberia and Guinea.
The virus spreads through close contact and health officials say stopping the spread of the disease in the areas hardest hit by the outbreak will prevent Ebola’s spread to other countries.
Dr Frieden told reporters on Monday the CDC was “looking forward” to working with states to put in place appropriate guidelines for returning workers.
But he said the agency was “concerned about some policies” being put into place.
Separately, the Pentagon has said about a dozen US troops retuning from West Africa are being isolated at a base in Italy “out of an abundance of caution”.
Pentagon spokesman Col Steven Warren told reporters none of the soldiers displayed symptoms of Ebola.