October 2, 2014 4:55 AM EDT

The director for the Centers for Disease Control and Prevention said Wednesday they are monitoring a Liberian man found to have Ebola in Dallas, as well as anyone he may have come into contact with.

Dr. Thomas Frieden said the agency would retrace every step Thomas Eric Duncan took in order to contain a possible outbreak.

“This is a tried and true reliable public-health strategy. We go from the moment he could have been infected, which is probably around the 24th, last Wednesday, and we retrace every step, every contact where he might have had direct physical contact with somebody, and for each one of those contacts, we will monitor them for 21 days after exposure, in conjunction with the local and state health department and the hospital to see if they develop symptoms,” he said.

Frieden was confident that an outbreak would not happen.

“That’s how you stop an Ebola outbreak. That’s what we’ll do in this case. There’s no doubt in my mind that we can stop it in its tracks here.”

Officials are monitoring at least a dozen people, including five children, the Wall Street Journal reports, but that number is likely to increase.

Duncan was admitted to hospital last Friday, but despite telling medical staff that he had recently visited Liberia, he was allowed to go home on a course of antibiotics.

So far, none of the people believed to have come into contact with the infected man have shown any symptoms of the disease.

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Write to Helen Regan at helen.regan@timeasia.com.

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