After previously listing his condition as serious, Texas Ebola patient Thomas Eric Duncan is now in critical condition, Texas Health Presbyterian Hospital spokeswoman Candace White said on Sunday.

US authorities said none of the people believed to have exposure to Duncan, including nine deemed to be at high risk, had shown any signs of Ebola infection.

The nine people who had definite contact with the Ebola patient - including family members, healthcare professionals - have been monitored and show no symptoms or fevers, Dr Tom Frieden, director of the Centers for Disease Control and Prevention said on Sunday.

"We have already gotten well over 100 inquiries of possible patients," he said.

"We've assessed every one of those and just this one patient has tested positive. We expect that we will see more rumors or concerns or possibilities of cases, until there is a positive laboratory test, that is what they are," he added.     

The group was among 50 people being monitored daily, but the other 40 are considered 'low risk', said Dr David Lakey, the commissioner of Texas department of state health services.
Health officials did not provide details on the location of those being monitored or where they interacted with Duncan.
The latest figure is a drastic reduction of a number that started at 100 after initial talks with Duncan and hospital officials.

"We will be looking very closely particularly at the nine individuals in the coming days, understanding that the peak period after exposure is about eight to nine days, but can be as long as 21 days," Frieden said.

Duncan was first sent home when he first sought medical care, leaving a four day span when he was sick and contagious while in contact with others, sparking concerns over how many others may have been exposed.

The first Ebola diagnosis in US has raised concerns about whether the disease that has killed 3,400 people in West Africa could spread in US.

Federal health officials say they are confident they can keep it in check.

US health officials were monitoring 50 people for Ebola exposure, 10 of whom are at 'high risk' of the disease after close contact with the first diagnosed American patient.
According to the WHO, the Ebola outbreak has killed more than 3,400 people, mostly in Africa.

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