DALLAS, Texas (AP) — The first Ebola patient diagnosed in the United States told health care workers on his initial hospital visit that he had recently been in an area affected by the deadly disease, but that information was not widely shared, a hospital official said yesterday.

Thomas Eric Duncan went to a Dallas emergency room Friday and explained that he was visiting the US from Liberia. He was sent home with antibiotics, according to his sister, Mai Wureh.

He returned two days later, after his condition worsened, and was admitted to Texas Health Presbyterian Hospital.

Dr Mark Lester, who works for the hospital’s parent company, said a nurse had asked Duncan whether he had been in any part of West Africa, where Ebola has killed thousands. But that “information was not fully communicated throughout the whole team.”

A day after the man’s diagnosis was confirmed, a nine-member team of federal health officials was tracking anyone who had close contact with him.

The team from the Centres for Disease Control and Prevention was in Dallas to work with local and state health agencies to ensure that those people are watched every day for 21 days.

“If anyone develops fever, we’ll immediately isolate them to stop the chain of transmission,” Dr Tom Frieden, the CDC director, said in an interview.

Duncan has been kept in isolation at the hospital since Sunday. He was listed in serious but stable condition.

Ebola is believed to have sickened more than 6,500 people in West Africa, and more than 3,000 deaths have been linked to the disease, according to the World Health Organisation.

Officials are monitoring 12 to 18 people who may have been exposed to the man, including three members of the ambulance crew that transported him to the hospital and five schoolchildren.

Some of the people are members of his family, but not all, Dallas city spokeswoman Sana Syed said.

The ambulance crew tested negative for the virus and was restricted to home while their conditions are observed. The children, who attend four separate schools, apparently had contact with the man over the weekend and then returned to classes this week. But school officials have said they showed no symptoms.

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.

Officials said there are no other suspected cases in Texas, but the diagnosis sent chills through the area’s West African community, whose leaders urged caution to prevent spreading the virus.

The man left Liberia on Sept 19, arrived the next day to visit relatives and started feeling ill four or five days later, Frieden said.

Stanley Gaye, president of the Liberian Community Association of Dallas-Fort Worth, said the 10,000-strong Liberian population in North Texas is skeptical of the CDC’s assurances because Ebola has ravaged their country.

“We’ve been telling people to try to stay away from social gatherings,” Gaye said Tuesday at a community meeting.

The CDC has not advised that people avoid large gatherings in this country.

The association’s vice president warned against alarm in the community.

“We don’t want to get a panic going,” said vice president Roseline Sayon. “We embrace those people who are coming forward. Don’t let the stigma keep you from getting tested.”

Frieden said he did not believe anyone on the same flights as the patient was at risk.

The man traveled from his home in the Liberian capital of Monrovia to Brussels and then to Dallas, according to a spokeswoman for the Belgium health ministry, Vinciane Charlier.

“Ebola doesn’t spread before someone gets sick, and he didn’t get sick until four days after he got off the airplane,” Frieden said.

Four American aid workers who became infected in West Africa have been flown back to the US for treatment after they became sick. They were treated in special isolation facilities at hospitals in Atlanta and Nebraska. Three have recovered.

A US doctor exposed to the virus in Sierra Leone is under observation in a similar facility at the National Institutes of Health.

The US has only four such isolation units, but Frieden said there was no need to move the latest patient because virtually any hospital can provide the proper care and infection control.

Passengers leaving Liberia pass through rigorous screening, the country’s airport authority said Wednesday. But those checks are no guarantee that an infected person won’t get through and airport officials would be unlikely to stop someone not showing symptoms, according to Binyah Kesselly, chairman of the Liberia Airport Authority’s board of directors.

CDC officials are helping staff at Monrovia’s airport, where passengers are screened for signs of infection, including fever, and asked about their travel history. Plastic buckets filled with chlorinated water for hand-washing are present throughout the airport.

Liberia is one of the three hardest-hit countries in the epidemic, along with Sierra Leone and Guinea.