The 50 were narrowed down from an initial pool of 100 people thought to have come into contact with the sick man.

They are being checked for fever twice daily, and are currently "doing well," said David Lakey, commissioner of the Texas Department of State Health Services.

"Most of these individuals are low risk. There are about 10 individuals that are at high risk, so we are watching those individuals very carefully."

The people are health care workers and those who came in close contact with Thomas Eric Duncan, who traveled from Liberia to Texas in late September and was announced Tuesday as the first diagnosed US case of Ebola.

The 50 people who came in contact with him will be followed for 21 days to see if they develop symptoms such as fever, aches, vomiting or diarrhea, according to the US Centers for Disease Control and Prevention (CDC).

"This does not imply that we have a high level of concern for most of these people," the head of CDC's national infectious diseases unit, Beth Bell, told reporters.

Duncan's girlfriend and three members of her family have meanwhile been ordered to stay inside in a Dallas apartment under police guard.

A hazardous materials team arrived on Saturday to remove the sheets and towels Duncan used while he was sick, according to pictures posted online by the Dallas City Hall.

A cleanup team was turned away on Friday over permit issues, said Clay Lewis Jenkins, a Dallas County judge.

"I went inside the apartment with two CDC epidemiologists last night to apologize to the family for the delay in getting those removed," Jenkins said.

CDC officials continued to monitor the health of the four people in the apartment, but Duncan's girlfriend, Louise, complained of the quarantine.

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