Story highlights U.S. official to CNN: The situation is a "screw-up"

Dallas mayor: The patient came into contact with up to 20 people

Hospital says symptoms 'did not warrant admission' last week

NIH official on hospital: "They dropped the ball"

The first person to be diagnosed with Ebola on American soil went to the emergency room last week, but was released from the hospital even though he told staff he had traveled from Liberia.

"A travel history was taken, but it wasn't communicated to the people who were making the decision. ... It was a mistake. They dropped the ball," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

"You don't want to pile on them, but hopefully this will never happen again. ... The CDC has been vigorously emphasizing the need for a travel history," Fauci told CNN's "The Lead with Jake Tapper."

Hospital officials have acknowledged that the patient's travel history wasn't "fully communicated" to doctors, but also said in a statement Wednesday that based on his symptoms, there was no reason to admit him when he first came to the emergency room last Thursday night.

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"At that time, the patient presented with low-grade fever and abdominal pain. His condition did not warrant admission. He also was not exhibiting symptoms specific to Ebola," Texas Health Presbyterian Hospital Dallas said.

The patient, identified by his half-brother as Thomas Eric Duncan , told hospital staff that he was from Liberia, a friend who knows him well said.

A nurse asked the patient about his recent travels while he was in the emergency room, and the patient said he had been in Africa, said Dr. Mark Lester, executive vice president of Texas Health Resources. But that information was not "fully communicated" to the medical team, Lester said.

The man underwent basic blood tests, but not an Ebola screening, and was sent home with antibiotics, said Dr. Edward Goodman with Texas Health Presbyterian Hospital.

Three days later, the man returned to the facility, where it was determined that he probably had Ebola. He was then isolated.

"The hospital followed all suggested CDC protocols at that time. Texas Health Presbyterian Hospital Dallas' staff is thoroughly trained in infection control procedures and protocols," the hospital said Wednesday.

The Centers for Disease Control and Prevention, which has helped lead the international response to Ebola, advises that all medical facilities should ask patients with symptoms consistent with Ebola for their travel history.

Duncan's travel history "was not acted upon in an appropriate way," said Dr. Sanjay Gupta, CNN's Chief Medical Correspondent.

"A nurse did ask the question and he did respond that he was in Liberia and that wasn't transmitted to people who were in charge of his care," Gupta said. "There's no excuse for this."

A U.S. official told CNN senior medical correspondent Elizabeth Cohen that the situation was clearly "a screw-up." A patient who shows up to a hospital with a fever and a history of travel to Liberia should be treated as an infection risk, the official said.

Asked repeatedly by Gupta whether the patient should have been tested for Ebola during his first visit to the hospital, CDC Director Dr. Thomas Frieden said officials were still looking at details about how the case was handled.

"We know that in busy emergency departments all over the country, people may not ask travel histories. I don't know if that was done here," Frieden said. "But we need to make sure that it is done going forward."

Friend: I called the CDC with concerns

Duncan is a 42-year-old Liberian national, according to his friend. This is Duncan's first trip to the United States, where he was visiting family and friends.

The close associate, who does not want to be identified because of the sensitivity of the case, contacted the CDC with concerns that the hospital wasn't moving quickly enough after Duncan's second hospital visit.

The associate said Duncan is "all right" now, but is in pain and hasn't eaten in a week.

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Photos: The Ebola epidemic Photos: The Ebola epidemic An Ebola survivor participates in a study in Monrovia, Liberia, on June 17, 2015. The country launched a five-year study to unravel the mystery of the long-term health effects that plague survivors of the viral disease. Since the epidemic started more than a year ago in a remote village in Guinea, more than 11,000 people have died, the vast majority in three West African nations, according to the latest numbers from the World Health Organization . And that number is believed to be low, since there was widespread under-reporting of cases, according to WHO. Hide Caption 1 of 45 Photos: The Ebola epidemic Women in Monrovia celebrate after the World Health Organization declared Liberia Ebola-free on May 9, 2015. Other cases have recurred since, however. Two people in Liberia have died of the disease since the end of June, just weeks after the WHO declared the nation free of the disease. Hide Caption 2 of 45 Photos: The Ebola epidemic A man walks past an Ebola awareness painting in Monrovia on March 22, 2015. Hide Caption 3 of 45 Photos: The Ebola epidemic Soldiers from the U.S. Army's 101st Airborne Division walk across the tarmac at Campbell Army Airfield before reuniting with their families at a homecoming ceremony March 21, 2015 in Fort Campbell, Kentucky. The 162 soldiers were deployed in Liberia, where they helped fight the spread of Ebola. Hide Caption 4 of 45 Photos: The Ebola epidemic Relatives weep for a loved one who it was believed died from Ebola, at a graveyard on the outskirts of Monrovia on March 11, 2015. Hide Caption 5 of 45 Photos: The Ebola epidemic Doctors Without Borders staffer Alex Eilert Paulsen watches as mattresses and bed frames burn at the Ebola Treatment Unit in Paynesville, Liberia, on January 31, 2015. The organization reduced its number of beds from 250 to 30 as gains were made in battling the virus. Hide Caption 6 of 45 Photos: The Ebola epidemic Pauline Cafferkey, a Scottish woman diagnosed with Ebola, is put on a plane in Glasgow, Scotland, on December 30, 2014. Cafferkey, a 39-year-old nurse who volunteered in Sierra Leone, was being transported to London for treatment. Hide Caption 7 of 45 Photos: The Ebola epidemic A child who survived the Ebola virus is fed by another survivor at a treatment center on the outskirts of Freetown, Sierra Leone, on November 11, 2014. Hide Caption 8 of 45 Photos: The Ebola epidemic Health workers in Monrovia cover the body of a man suspected of dying from the Ebola virus on October 31, 2014. Hide Caption 9 of 45 Photos: The Ebola epidemic Kaci Hickox leaves her home in Fort Kent, Maine, to take a bike ride with her boyfriend on October 30, 2014. Hickox, a nurse, recently returned to the United States from West Africa, where she treated Ebola victims. State authorities wanted her to avoid public places for 21 days -- the virus' incubation period. But Hickox, who twice tested negative for Ebola, said she would defy efforts to keep her quarantined at home. Hide Caption 10 of 45 Photos: The Ebola epidemic Health officials in Nairobi, Kenya, prepare to screen passengers arriving at the Jomo Kenyatta International Airport on October 28, 2014. Hide Caption 11 of 45 Photos: The Ebola epidemic U.S. President Barack Obama hugs Ebola survivor Nina Pham in the Oval Office of the White House on October 24, 2014. Pham, one of two Dallas nurses diagnosed with the virus, was declared Ebola-free after being treated at a hospital in Bethesda, Maryland. The other nurse, Amber Vinson (not pictured), was treated in Atlanta and also declared Ebola-free. Hide Caption 12 of 45 Photos: The Ebola epidemic Health workers in Port Loko, Sierra Leone, transport the body of a person who is suspected to have died of Ebola on October 21, 2014. Hide Caption 13 of 45 Photos: The Ebola epidemic Health workers bury a body on the outskirts of Monrovia on October 20, 2014. Hide Caption 14 of 45 Photos: The Ebola epidemic Garteh Korkoryah, center, is comforted during a memorial service for her son, Thomas Eric Duncan, on October 18, 2014, in Salisbury, North Carolina. Duncan, a 42-year-old Liberian citizen, died October 8 in a Dallas hospital. He was in the country to visit his son and his son's mother, and he was the first person in the United States to be diagnosed with Ebola. Hide Caption 15 of 45 Photos: The Ebola epidemic Boys run from blowing dust as a U.S. military aircraft leaves the construction site of an Ebola treatment center in Tubmanburg, Liberia, on October 15, 2014. Hide Caption 16 of 45 Photos: The Ebola epidemic Aid workers from the Liberian Medical Renaissance League stage an Ebola awareness event October 15, 2014, in Monrovia. The group performs street dramas throughout Monrovia to educate the public on Ebola symptoms and how to handle people who are infected with the virus. Hide Caption 17 of 45 Photos: The Ebola epidemic Ebola survivors prepare to leave a Doctors Without Borders treatment center after recovering from the virus in Paynesville, Liberia, on October 12, 2014. Hide Caption 18 of 45 Photos: The Ebola epidemic A man dressed in protective clothing treats the front porch of a Dallas apartment on October 12, 2014. The apartment is home to one of the two nurses who were diagnosed with Ebola after treating Thomas Eric Duncan, a Liberian national who traveled to Dallas and later died from the virus. Hide Caption 19 of 45 Photos: The Ebola epidemic A woman crawls toward the body of her sister as a burial team takes her away for cremation October 10, 2014, in Monrovia. The sister had died from Ebola earlier in the morning while trying to walk to a treatment center, according to her relatives. Hide Caption 20 of 45 Photos: The Ebola epidemic A man digs a grave on October 7, 2014, outside an Ebola treatment center near Gbarnga, Liberia. Hide Caption 21 of 45 Photos: The Ebola epidemic A person peeks out from the Dallas apartment where Thomas Eric Duncan, the first person diagnosed with the Ebola virus in the United States, was staying on October 3, 2014. Hide Caption 22 of 45 Photos: The Ebola epidemic A girl cries as community activists approach her outside her Monrovia home on October 2, 2014, a day after her mother was taken to an Ebola ward. Hide Caption 23 of 45 Photos: The Ebola epidemic A health official uses a thermometer September 29, 2014, to screen a Ukrainian crew member on the deck of a cargo ship at the Apapa port in Lagos, Nigeria. Hide Caption 24 of 45 Photos: The Ebola epidemic Workers move a building into place as part of a new Ebola treatment center in Monrovia on September 28, 2014. Hide Caption 25 of 45 Photos: The Ebola epidemic Medics load an Ebola patient onto a plane at Sierra Leone's Freetown-Lungi International Airport on September 22, 2014. Hide Caption 26 of 45 Photos: The Ebola epidemic A few people are seen in Freetown during a three-day nationwide lockdown on September 21, 2014. In an attempt to curb the spread of the Ebola virus, people in Sierra Leone were told to stay in their homes. Hide Caption 27 of 45 Photos: The Ebola epidemic Supplies wait to be loaded onto an aircraft at New York's John F. Kennedy International Airport on September 20, 2014. It was the largest single shipment of aid to the Ebola zone to date, and it was coordinated by the Clinton Global Initiative and other U.S. aid organizations. Hide Caption 28 of 45 Photos: The Ebola epidemic A child stops on a Monrovia street September 12, 2014, to look at a man who is suspected of suffering from Ebola. Hide Caption 29 of 45 Photos: The Ebola epidemic After an Ebola case was confirmed in Senegal, people load cars with household items as they prepare to cross into Guinea from the border town of Diaobe, Senegal, on September 3, 2014. Hide Caption 30 of 45 Photos: The Ebola epidemic A health worker wearing a protective suit conducts an Ebola prevention drill at the port in Monrovia on August 29, 2014. Hide Caption 31 of 45 Photos: The Ebola epidemic A burial team from the Liberian Ministry of Health unloads bodies of Ebola victims onto a funeral pyre at a crematorium in Marshall, Liberia, on August 22, 2014. Hide Caption 32 of 45 Photos: The Ebola epidemic Dr. Kent Brantly leaves Emory University Hospital on August 21, 2014, after being declared no longer infectious from the Ebola virus. Brantly was one of two American missionaries brought to Emory for treatment of the deadly virus. Hide Caption 33 of 45 Photos: The Ebola epidemic An Ebola Task Force soldier beats a local resident while enforcing a quarantine on the West Point slum on August 20, 2014. Hide Caption 34 of 45 Photos: The Ebola epidemic Local residents gather around a very sick Saah Exco, 10, in a back alley of the West Point slum on August 19, 2014. The boy was one of the patients that was pulled out of a holding center for suspected Ebola patients after the facility was overrun and closed by a mob on August 16. A local clinic then refused to treat Saah, according to residents, because of the danger of infection. Although he was never tested for Ebola, Saah's mother and brother died in the holding center. Hide Caption 35 of 45 Photos: The Ebola epidemic Workers prepare the new Ebola treatment center on August 17, 2014. Hide Caption 36 of 45 Photos: The Ebola epidemic Liberian police depart after firing shots in the air while trying to protect an Ebola burial team in the West Point slum of Monrovia on August 16, 2014. A crowd of several hundred local residents reportedly drove away the burial team and their police escort. The mob then forced open an Ebola isolation ward and took patients out, saying the Ebola epidemic is a hoax. Hide Caption 37 of 45 Photos: The Ebola epidemic A health worker disinfects a corpse after a man died in a classroom being used as an Ebola isolation ward August 15, 2014, in Monrovia. Hide Caption 38 of 45 Photos: The Ebola epidemic Aid worker Nancy Writebol, wearing a protective suit, gets wheeled on a gurney into Emory University Hospital in Atlanta on August 5, 2014. A medical plane flew Writebol from Liberia to the United States after she and her colleague Dr. Kent Brantly were infected with the Ebola virus in the West African country. Hide Caption 39 of 45 Photos: The Ebola epidemic Members of Doctors Without Borders adjust tents in the isolation area in Kailahun on July 20, 2014. Hide Caption 40 of 45 Photos: The Ebola epidemic Boots dry in the Ebola treatment center in Kailahun on July 20, 2014. Hide Caption 41 of 45 Photos: The Ebola epidemic Dr. Jose Rovira of the World Health Organization takes a swab from a suspected Ebola victim in Pendembu, Sierra Leone, on July 18, 2014. Hide Caption 42 of 45 Photos: The Ebola epidemic Red Cross volunteers disinfect each other with chlorine after removing the body of an Ebola victim from a house in Pendembu on July 18, 2014. Hide Caption 43 of 45 Photos: The Ebola epidemic A scientist separates blood cells from plasma cells to isolate any Ebola RNA and test for the virus April 3, 2014, at the European Mobile Laboratory in Gueckedou, Guinea. Hide Caption 44 of 45 Photos: The Ebola epidemic Health specialists work March 31, 2014, at an isolation ward for patients at the facility in southern Guinea. Hide Caption 45 of 45

The patient is now under intensive care and isolated, Frieden said.

He is in serious condition, the hospital told CNN. Neither the hospital nor government officials have identified Duncan by name.

Obama administration recirculates guidelines

It's unknown whether others were infected after Duncan's first visit to the hospital. People who have Ebola are contagious -- but only through contact with infected bodily fluids -- when they display active symptoms of the virus, such as a high fever, severe headache, diarrhea and vomiting, among others. It's not like a cold or the flu, which can be spread before symptoms show up, and it doesn't spread through the air.

Liberia is one of the hotspots in a large outbreak of Ebola in West Africa, with 3,458 cases and 1,830 deaths as of September 23, according to the World Health Organization. Other countries affected include Guinea, Nigeria and Sierra Leone. In total, more than 3,000 people have died in those countries from Ebola, and more than 6,500 have contracted the disease.

This summer, two American missionaries who were working in Liberia contracted the virus and were brought back to the United States, where they were treated with the experimental drug ZMapp . Another American doctor working with the same charity was also infected in Liberia and brought home for treatment. They all have since recovered from the virus and were released from care.

The CDC has ramped up a national effort to stem the spread of Ebola, and in September President Barack Obama spoke at CDC headquarters in Atlanta. He called the virus a global health and security threat, and pledged U.S. assistance to the affected countries to try to stem the tide of the disease.

After the Dallas diagnosis, the Obama administration is recirculating its guidance about how to respond to the virus, White House spokesman Josh Earnest told reporters.

"In light of this incident," Earnest said, "the administration has taken the step of recirculating our guidance to law enforcement agencies that are responsible for securing the border, to those agencies that represent individuals who staff the airline industry and to medical professionals all across the country, to make sure people are aware there is an important protocol that should be implemented if an individual presents with symptoms that are consistent with Ebola."

Finding the people the man came in contact with

The patient came into contact with up to 20 individuals, Dallas Mayor Mike Rawlings told CNN.

A CDC team is in Dallas helping to find anyone he may have come in contact with, Frieden said.

Once those people are identified, they will be monitored for 21 days -- taking their temperatures twice a day -- in cooperation with local and state health officials, Frieden said.

Some school-age children have been in contact with the Ebola patient, but the students haven't exhibited symptoms of the deadly virus, authorities said.

Five students at four different schools came into contact with the man, Dallas Superintendent Mike Miles said.

The children are being monitored at home, and the schools they attended remain open, he said.

Paramedics who transported the patient to the hospital have been isolated, Rawlings' chief of staff said. They have not shown symptoms of the disease so far, Frieden said.

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The ambulance used to carry the patient was still in use for two days after the transport, city of Dallas spokeswoman Sana Syed said.

But she emphasized that the paramedics decontaminated the ambulance, as they do after every transport, according to national standards.

Air travel testing

The Ebola patient told authorities he flew part of his trip on United Airlines, a spokesperson for the airline said, citing information from the CDC. The airline believes the patient flew from Brussels to Washington Dulles and then from Dulles to Dallas-Fort Worth on September 20, the spokesperson said.

"The director of the CDC has stated there is 'zero risk of transmission' on any flight on which the patient flew because he was not symptomatic until several days after his trip and could not have been contagious on the dates he traveled," the spokesperson said.

Every person who travels by air is screened before departure and at arrival in Liberia, Guinea and Sierra Leone, but because the man says he began feeling ill days after landing in the United States, a screening test in West Africa would likely have not turned up that he had Ebola.

However, it's unclear what kind of screening someone flying from West Africa might receive when they land in the United States, Cohen said. The CNN correspondent and her crew recently reported in and flew from West Africa, where she said they were screened numerous times for Ebola by having their temperatures taken at the airport.

But when they arrived back in the United States, and asked travel officials about whether their temperatures would be taken or whether they'd be screened for Ebola, they were given unclear explanations about how the process worked and ultimately were not tested.

Regardless, the CDC maintains that passengers on planes with the Texas patient were likely not at risk because the man was not displaying active symptoms.