Health officials in the US state of Texas on Friday narrowed down the list of people who may have had direct and indirect contact with the country' s first diagnosed Ebola patient to 50 people, and started to clean up the apartment where the patient stayed before being hospitalized.

A group of federal, state and local officials told the media at a press conference held on Friday night that they have pinpointed ten people, among the 50 people, at higher risk of being infected.

The 50 people include those who had person-to-person contact with the patient and those who in turn came in contact with them. All have been put under daily check for early signs of the deadly disease.

The tracking list is half less than the number officials announced a day earlier, when a spokesperson for Texas health department said that 100 people may have possibly been exposed to the Ebola patient.

Among the dozens, a core group of 12 to 18 people were initially believed to have had close contact with the patient. Officials adjusted the number to ten Friday, among whom are four family members who shared an apartment with him in northeast Dallas.

TV footage showed crews wearing yellow protective suits entered the apartment Friday afternoon to decontaminate soiled sheets, towels and other personal belongings of the patient. The contaminated materials were put into sealed plastic barrels and carried away from the apartment. Contractors in charge of the cleanup will dispose of the hazardous materials once they get permit from authorities.

The four family members of the patient, who have been put in quarantine, were moved from the apartment to an undisclosed location Friday, officials said. They have to remain indoors through Oct. 19 when the incubation period should be over.

Officials on Friday assured the public repeatedly that the only person showing Ebola symptoms is the patient, identified as Thomas Eric Duncan, a Liberian visitor in his mid-40s.

Duncan arrived in Dallas on Sept. 20 and began to show signs of Ebola several days later. He went to a hospital on Sept. 26, only to be dismissed with some antibiotics.

He returned to the hospital on Sept. 28, this time in an ambulance, and was confirmed to be the first diagnosed patient in the United States on Sept. 30. He was listed in "serious but stable" condition on Thursday.