This 2011 photo provided by Wilmot Chayee shows Thomas Eric Duncan, right, with friend Wilmot Chayee at a wedding in Ghana. Duncan, who became the first patient diagnosed in the U.S with Ebola, has been kept in isolation at a hospital since Sunday, Sept. 28, 2014. He was listed in serious but stable condition. (AP Photo/Wilmot Chayee)

The Dallas hospital that failed to admit a man who later tested positive for Ebola said Thursday night that a nurse had noted his recent trip from Africa. But because of an electronic records “flaw,” his travel history wasn’t seen by the physician who released him. As a result, as many as 100 people may have come into contact with the Liberian man, who is the first person to be diagnosed with Ebola in the United States.

Thomas Eric Duncan was released from Texas Health Presbyterian Hospital Dallas on Sept. 26 after showing early symptoms of Ebola — fever, stomach pain and a sharp headache. Two days later, he was diagnosed with the disease and placed in isolation.

The handling of Duncan — from Liberia to the U.S. — has raised questions about the world’s general preparedness for coping with the epidemic beyond its epicenter in West Africa.

A more complete picture of Duncan’s recent travels was emerging Thursday night, though it’s still unclear exactly why he got on an airplane bound for the United States.

Back in Liberia, Duncan had been in direct contact with an Ebola-stricken neighbor, according to the Associated Press. He reportedly rushed to the 19-year-old woman’s aid when she began convulsing and rode with her in a taxi to a nearby hospital, where she later died. Everyone in the village assumed her illness was related to her pregnancy. But she turned out to have Ebola.

It’s not clear whether Duncan knew she had the virus when he decided to leave Liberia.

In an airport screening questionnaire, he said he had not come into contact with an Ebola patient. And before leaving the country, he had his temperature checked at the airport in Monrovia — and he did not have a fever.

This Oct. 2, 2014 photo shows a copy of a passenger health screening form filled out by Ebola patient Thomas Eric Duncan, which was obtained by the Associated Press from the Liberia Airport Authority. Liberia plans to prosecute Duncan, who brought Ebola into the U.S., alleging that he lied on a health questionnaire about not having any contact with an infected person, authorities said Thursday, Oct. 2, 2014. (AP Photo/Kiichiro Sato)

On Thursday, Liberian authorities said they plan to prosecute him for lying on the questionnaire.

United Airlines is calling passengers who flew with Duncan to tell them they shared a flight with him from Brussels to Washington, D.C., and then to Dallas on Sept. 20.

After the flights, the airline said, the two airplanes in which Duncan flew underwent a “thorough cleaning, including cleaning of lavatories and galleys with heavy-duty all-purpose cleaners and wiping tray tables and arm rests with disinfectant,” according to the Los Angeles Times.

Still, a researcher with the Center for Immigration Studies in Washington said Duncan shouldn’t have been issued a visitor’s visa in the first place.

“If you look at his circumstances, it should have been really tough for him to qualify for a visa,” Jessica Vaughn said, explaining that Duncan was reportedly single, jobless, living away from his home country and had a number of relatives in the U.S. — all factors that often indicate a person is unlikely to return home after their visa expires. “He clearly appears unqualified.”

Duncan showed up at Texas Health Presbyterian Hospital Dallas the night of Sept. 25 with a temperature of 100.1 degrees, abdominal pain that had persisted for two days, decreased urination and a headache, according to the hospital. Though the symptoms can be early warning signs of Ebola, they are not specific to the disease and can be associated with other illnesses.

Duncan denied any nausea, vomiting or diarrhea — other symptoms consistent with the virus. He also told a nurse that he had not been around anyone who had been ill.

When hospital staff asked him whether he had traveled outside the United States in the past several weeks, he said he had been in Africa. A nurse entered that information into the hospital’s electronic medical record system but apparently did not take any further action.

Thursday night, the hospital said it released him because “separate physician and nursing workflows” kept physicians from seeing his travel history, which would have shown his recent presence in Liberia and possibly triggered extra scrutiny. The statement said that the “documentation of the travel history was located in the nursing workflow portion” of the electronic health records and “would not automatically appear in the physician’s standard workflow.”

So physicians never weighed in on his release.

Two days after he was sent home, witnesses said, he was seen vomiting on the ground outside an apartment complex as he was put into an ambulance.

“His whole family was screaming. He got outside and he was throwing up all over the place,” resident Mesud Osmanovic, 21, told Reuters on Wednesday.

As a result, the hospital said it has put the travel history documentation in both workflows. “It also has been modified to specifically reference Ebola-endemic regions in Africa,” the statement said. “We have made this change to increase the visibility and documentation of the travel question in order to alert all providers. We feel that this change will improve the early identification of patients who may be at risk for communicable diseases, including Ebola.”

Liberian President Ellen Johnson Sirleaf told CBC News she was “very saddened” and “very angry” with Duncan for putting Americans at risk.

“I just hope that nobody else gets infected,” she said.