A child who was recently in west Africa is being tested for Ebola after developing a fever while under observation in hospital in New York.
The five-year-old arrived from Guinea on Saturday and has a high fever.
Meanwhile a nurse who was threatening legal action, after being held in quarantine in neighbouring New Jersey, has been told she can now go home.
It was confirmed by New Jersey Governor Chris Christie:
From @NJDeptofhealth: "Since testing negative for Ebola early Saturday morning, the patient being monitored in isolation..." (cont
— Governor Christie (@GovChristie) October 27, 2014
"...has thankfully been symptom free for the last 24 hrs. After being evaluated by CDC & her clinicians the patient is being discharged.”
— Governor Christie (@GovChristie) October 27, 2014
Kaci Hickox had been put into isolation, despite testing negative for the virus.
The Doctors Without Borders worker returned to the US on Friday and was promptly put into isolation at a New Jersey hospital.
She has tested free of the deadly virus, but was told she would be unable to leave for another 21 days - when the disease's incubation period ends.
Her lawyer said the order violated her constitutional rights.
Writing in The Dallas Morning News before the lawsuit was announced, Ms Hickox said: "This is not a situation I would wish on anyone, and I am scared for those who will follow me.
"I am scared that, like me, they will arrive and see a frenzy of disorganisation, fear and, most frightening, quarantine."
She said that upon telling a border official she had just arrived back, she was immediately ushered into a private room before having questions "barked" at her.
She said she was made to wait hours with little to eat.
"I... thought of many colleagues who will return home to America and face the same ordeal. Will they be made to feel like criminals and prisoners?" Ms Hickox said.
"The US must treat returning health care workers with dignity and humanity," said the nurse, who has a bed, a portable toilet and a sink, but no shower.
Three states - New York, New Jersey and Illinois - introduced the mandatory 21-day quarantine period for anyone who has been involved in treating victims in West Africa.
Other states, including Virginia and Georgia, are also considering whether to impose the same regime.
However, Ms Hickox's treatment has been widely criticised.
Mounting pressure
Under mounting pressure, the governors of New York and New Jersey said on Sunday evening that quarantined medical workers who did not show symptoms could be allowed to remain at home.
New York Governor Andrew Cuomo said: "We're doing everything possible. Some people say we're being too cautious - I'll take that criticism."
Under the protocols, the New York state will also pay for any lost compensation if the quarantined workers are not paid by a volunteer organisation.
On Sunday, a top US health official warned that the quarantines could discourage qualified doctors from volunteering in West Africa.
Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said: "We do not want to put them in a position where it makes it very, very uncomfortable for them to even volunteer to go.
"If we don't have our people volunteering to go over there, then you're going to have other countries that are not going to do it and then the epidemic will continue to roar."
The number of Ebola cases worldwide has now exceeded 10,000, with nearly 5,000 deaths, according to the World Health Organisation.
The US quarantines followed the positive diagnosis of doctor Craig Spencer, who fell ill days after returning to his New York City home from treating Ebola patients in Guinea.
Originally published at 10:25am
