ATLANTA (CNN) -- Some school-age children have been in contact with the U.S. Ebola patient being treated in Dallas, Texas Gov. Rick Perry said Wednesday.
Five students at four different schools have come into contact with the Ebola patient, Dallas Superintendent Mike Miles added, but none has exhibited symptoms. The children are being monitored at home, and the schools remain open, Miles said. Between 12 and 18 people have been identified as coming into contact with the patient, officials added.
Concern about the possible spread of the killer virus comes less than a day after the Centers for Disease Control and Prevention announced that, for the first time, a person with Ebola was diagnosed on American soil.
How that case was handled has sparked many serious questions.
The patient, a man, walked into an emergency room at Texas Health Presbyterian Hospital in Dallas on September 26. A nurse asked him for his travel history while he was in the emergency room, and the patient said he had traveled to 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, who had just flown from Liberia to the United States, underwent basic blood tests, but not an Ebola screening, and was sent home with antibiotics, said Dr. Edward Goodman with Texas Health Presbyterian Hospital.
Two days later, on September 28, the man returned to the facility, where it was determined that he probably had Ebola. He was then isolated. He tested positive for the virus Tuesday, health officials said.
The CDC, 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.
It's possible that others were infected because of the lapse. 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.
That the man had recently arrived in the United States from Liberia should have been a huge red flag, if he was asked about his travels. 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.
Ebola patient in serious condition
The patient in Dallas is now under intensive care and isolated at Texas Health Presbyterian Hospital, said CDC Director Dr. Thomas Frieden.
He is in serious condition, the hospital told CNN Wednesday.
The man flew from Liberia and arrived in Dallas to visit family on September 20, Frieden explained. He started feeling ill around September 24 and sought medical care on September 26, he added.
CNN Chief Medical Correspondent Dr. Sanjay Gupta asked Frieden Wednesday on "New Day" if the man should have been tested for Ebola on his first visit to the hospital, and if he should have been asked about his recent travel history.
"That's one of the things we'll be looking at," Frieden said. "But we're reiterating the message for every health worker in this country -- think about travel history. If someone's been in West Africa within 21 days and they've got a fever, immediately isolate them and get them tested for Ebola."
Gupta then asked Frieden to explain guidance the CDC has issued on that and again asked: "Should this person have been tested?" "We weren't there so I can't tell you exactly what that person said..." Frieden responded.
Gupta interjected, "You're advising public health departments. Last time I was here (at the Centers for Disease Control and Prevention in Atlanta) there was a call with many primary care doctors to educate them on this exact issue. That was a couple of months ago. Should this person have been tested?"
Frieden answered, "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. But we need to make sure that it is done going forward."
Air travel testing
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, said CNN's Senior Medical Correspondent Elizabeth Cohen. She 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 if 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 the Texas man's plane were likely not at risk because the man was not displaying active symptoms on the flight.
Frieden explained that people who have Ebola are not able to spread the disease unless they are symptomatic.
Paramedics who transported the patient to the hospital have been isolated, Dallas Mayor Mike Rawlings' chief of staff said. They have not shown symptoms of the disease so far, Frieden said.
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.
Finding the people the man came into contact with
During the time he was symptomatic, the man did have a handful of contacts with people, Frieden said.
A CDC team headed to Dallas to help investigate those contacts.
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 Wednesday.
But Gupta pointed out that the people identified as contacts aren't, as protocol, quarantined unless they are symptomatic.
"We don't want to isolate parts of the world, or people who aren't sick," Frieden said, "because that's going to drive people underground and make it harder to contain this outbreak."