As the first Ebola patient diagnosed in the United States fights for his life and health officials try to contain the deadly virus' spread, a portrait of him -- and of the web of contacts he may have made in the days since he arrived in Dallas from West Africa -- is emerging.
Here's what we know so far about the patient, how he got here, whom he may have exposed to Ebola, how the virus may have been spread and what could happen next.
WHO IS THE EBOLA PATIENT?
Thomas Eric Duncan, a Liberian man with family in the United States, boarded a Brussels-bound plane in his hometown of Monrovia en route to Dallas on Sept. 19, days after neighbors in Monrovia said he helped take a woman dying of Ebola to the hospital. It is unclear whether he knew of her diagnosis before traveling. The New York Times reported that the woman had been turned away because there was no room in the hospital's Ebola ward. She died several hours after she was brought back home.
His brother in Phoenix, Arizona, told The Associated Press that Duncan had headed to the United States to be with his girlfriend and child. He said he did not believe Duncan knew he had Ebola before he left Liberia.
HOW DID HE GET HERE?
Duncan is believed to have flown to the U.S. via Brussels on Sept. 20. United Airlines believes he took two connecting United flights that day to get to Dallas — flying from Brussels to Washington Dulles on Flight 951 and then from Dulles to Dallas-Fort Worth on Flight 822 the same day.
He boarded those flights, according to the Liberian government, after answering "no" at the airport to a health screening form's questions about whether he had cared for anybody with the virus or touched the body of anyone who died in an area where Ebola is prevalent.
Liberia says it will prosecute him for lying on the forms, though it is unclear whether Duncan knew the woman he had helped had Ebola. Texas officials have also said they are considering whether to bring charges against Duncan.
WHAT HAS HE DONE SINCE HE GOT HERE?
Duncan was taken to the emergency room at Texas Health Presbyterian Hospital after 10 p.m. Sept. 25 — not Sept. 26, as officials from the Centers for Disease Control and Prevention had earlier said — with a low-grade fever and abdominal pain.
Hospital officials at first said Duncan told a nurse that he had traveled from Liberia, but that information was not passed on to other workers there. Doctors, apparently not suspecting Ebola, diagnosed him with a low-risk infection and sent him home with antibiotics. The hospital initially said flaws in its electronic health record-keeping, not human error, had caused doctors to miss the diagnosis but later acknowledged that doctors did have access to the information that Duncan had traveled from Liberia.
Duncan returned to the hospital by ambulance on Sunday, Sept. 28, and was isolated. NBC News reported that a neighbor said that Duncan was "throwing up all over the place" as he was bundled into an ambulance.
A specimen sent to a state lab in Austin confirmed Tuesday, Sept. 30, that Duncan had contracted Ebola. Those test results were confirmed by the CDC in Atlanta.
When Duncan was hospitalized, he was listed in serious but stable condition, but is now in critical condition. The director of the Centers for Disease Control and Prevention, Dr. Thomas Frieden, said on CNN on Oct. 5 that Duncan is "fighting for his life."
Relatives in North Carolina say doctors have told them he is on a respirator and a dialysis machine. He has been given an experimental drug called brincidofovir.
WHO MAY HAVE BEEN EXPOSED?
The four people living in the apartment where Duncan was staying when he fell ill — a woman, her 13-year-old son and two young men — were moved to a new apartment Friday, after earlier being ordered to stay in their contaminated apartment in court-ordered quarantine under armed guard.
Duncan and the woman, Louise Troh, had a son together in the early 1990s after meeting in a refugee camp in the Ivory Coast, where both had fled Liberia's civil war, The New York Times reported. They had recently revived their relationship and were planning to marry, Troh's pastor has said.
Texas health officials, meanwhile, are focusing their efforts to contain the virus. They have narrowed their monitoring to a group of about 50 people who may have had some level of exposure to Duncan, after earlier saying they would reach out to as many as 100 who may have had direct contact with him.
Among those are 12 to 18 people who came in direct contact with Duncan, including an ambulance crew and a group of school children. Three siblings who attend Wallace Elementary School in Richardson were sent home Thursday after authorities learned they may have come in contact with him, after five students at four different Dallas schools were sent home earlier in the week.
A homeless man who was the next patient to ride in the ambulance used to transport Duncan to the hospital disappeared. But he has since been located and also is being monitored.
None of those people is showing symptoms, but health officials have educated them about Ebola and told them to contact them if they fall ill, a health official told The Associated Press.
Because Duncan did not fall ill for several days after he arrived in Dallas, the CDC says the other passengers on the flights he took are not at risk. Duncan showed no symptoms of Ebola when he traveled to the U.S., and he registered no fever when his temperature was checked at the Monrovia airport, CDC chief Frieden told reporters on Thursday.
HOW MIGHT EBOLA HAVE BEEN SPREAD?
Duncan may have been infected with Ebola from helping to get his landlord's Ebola-stricken daughter to the hospital in a taxi.
Ebola can only be spread by infected people who show symptoms. The virus can be spread through the blood or other bodily fluids of an infected person, or an infected person's body. It can also be spread by objects contaminated with Ebola, like syringes or other medical equipment, and by infected animals or meat. Contaminated objects can be disinfected with bleach.
If an exposed person does not develop symptoms within 21 days of exposure, the person will not become sick with Ebola, according to the CDC — though the virus has been found in semen for up to three months after exposure.
WHAT HAPPENS NEXT?
The four people with whom Duncan was staying were moved to a new, clean apartment on Friday, Oct. 3, just after crews finished decontaminating their apartment.
For days they had been ordered not to leave that apartment. On Friday, that changed, after the apartment was cleaned and the sheets and dirty towels Duncan had used while sick were removed.
A Dallas County official apologized to the family for how long it took to remove those items from the apartment; officials said they had had trouble finding a contractor willing to clean up the apartment.
