DALLAS: The first case of Ebola diagnosed in the United States was confirmed on Tuesday in a patient who recently travelled from Liberia to Dallas — a sign of the far-reaching impact of the out-of-control epidemic in West Africa.

The unidentified man was critically ill and has been in isolation at Texas Health Presbyterian Hospital since Sunday, federal health officials said. They would not reveal his nationality or age.

Authorities have begun tracking down family, friends and anyone else who may have come in close contact with him and could be at risk for becoming ill.

But officials said there were no other suspected cases in Texas. At the Centres for Disease Control and Prevention, Director Tom Frieden said the man left Liberia on Sept 19, arrived the next day to visit relatives and started feeling ill four or five days later. He said it was not clear how the patient became infected.

There was no risk to any fellow airline passengers because the man had no symptoms when he was travelling, Frieden said.

Ebola symptoms can include fever, muscle pain, vomiting and bleeding, and can appear as long as 21 days after exposure to the virus. The disease is not contagious until symptoms begin, and it takes close contact with bodily fluids to spread. “I have no doubt that we’ll stop this in its tracks in the US. But I also have no doubt, that as long as the outbreak continues in Africa, we need to be on our guard,” Frieden told reporters.

“It is certainly possible that someone who had contact with this individual, a family member or other individual, could develop Ebola in the coming weeks,” he added. “But there is no doubt in my mind that we will stop it here.”

He said he didn’t believe anyone on the same flights as the patient was at risk. “Ebola doesn’t spread before someone gets sick and he didn’t get sick until four days after he got off the aeroplane,” Frieden said.

He briefed President Barack Obama by phone about the diagnosis, the White House said.

Word of the infection alarmed the local Liberian community. “People have been calling, trying to find out if anybody knows the family,” said Stanley Gaye, president of the Liberian Community Association of Dallas-Fort Worth.

Published in Dawn, October 2nd, 2014