DALLAS — A Dallas emergency room sent a man with Ebola home last week, even though he told a nurse that he had been in disease-ravaged West Africa, and officials at the hospital are considering if they would have acted differently had the entire medical staff been aware.

The decision by Texas Health Presbyterian Hospital to release the patient, who had recently arrived from Liberia, could have put others at risk of exposure to Ebola before the man went back to the E.R. a couple of days later when his condition worsened.

A nine-member team of federal health officials was tracking anyone who had close contact with the man after he fell ill on Sept. 24. The group of 12 to 18 people included three members of the ambulance crew that took him to the hospital, as well as a handful of schoolchildren.

They will be checked every day for 21 days, the disease’s incubation period.

“That’s how we’re going to break the chain of transmission, and that’s where our focus has to be,” Dr. Tom Frieden, director of the Centers for Disease Control and Prevention, told The Associated Press Wednesday.

The CDC reminded health care providers to ask patients with symptoms if they’ve traveled recently. The American College of Emergency Physicians planned to alert its members as well.

The patient explained to a nurse last Thursday that he was visiting the U.S. from Africa, but that information was not widely shared, said Dr. Mark Lester, who works for the hospital’s parent company.

“Regretfully, that information was not fully communicated” throughout the medical team, Lester said. Instead, the man was diagnosed with a low-risk infection and sent home.

He was prescribed antibiotics, according to his sister, Mai Wureh, who identified her brother, Thomas Eric Duncan, as the infected man in an interview with The Associated Press.

Texas Health Presbyterian Hospital is reviewing how the situation would have been handled if all staff had been aware of the man’s circumstances.

“(Hospital officials) told me that is something they are looking into,” hospital spokesman Candace White said.

David Wright, regional director of the U.S. Centers for Medicare & Medicaid Services, wouldn’t say if the hospital was under investigation. Wright said that in cases they do handle, federal investigators examine if a hospital complied with a “reasonable physician standard” in deciding whether to admit a patient with a potential medical emergency.

“It really comes down to whether the hospital did the proper screening ... or not,” he said.

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

Hospital epidemiologist Dr. Edward Goodman said the patient had a fever and abdominal pain during his first E.R. visit, not the riskier symptoms of vomiting and diarrhea.

But the diagnosis, and the hospital’s slip-up, highlighted the wider threat of Ebola, even far from Africa.

“The scrutiny just needs to be higher now,” said Dr. Rade Vukmir, a spokesman for the American College of Emergency Physicians.

Ebola is believed to have sickened more than 7,100 people in West Africa and killed more than 3,300, according to the World Health Organization. Liberia is one of the three countries hit hardest in the epidemic, along with Sierra Leone and Guinea.

In Texas, neither the ambulance crew nor the children showed any symptoms and were being monitored at home. It was not clear how Duncan knew the children, but his sister said he had been visiting with family, including two nephews.

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. It spreads only by contact with an infected person’s bodily fluids.

The man left Liberia on Sept. 19, flying from Brussels to Dulles Airport near Washington. He then boarded a flight for Dallas-Fort Worth, according to airlines, and arrived the next day.

He started feeling ill four or five days later.