The Centers for Disease Control and Prevention has confirmed the first patient to be diagnosed with Ebola in the United States is at a hospital in Dallas. But they say there's "zero risk" he infected anyone else on his flight here and they're confident the virus will not spread widely in the United States.

Four other people with Ebola — all medical volunteers working in West Africa — have been evacuated to the U.S. for treatment, but this is the first case in a traveler. Three of them have recovered.

"I have no doubt that we will be able to stop this in the United States," CDC director Dr. Tom Frieden told a news conference.

"At this point there is zero risk of transmission on the flight. He was checked for fever before getting on the flight," Frieden said. "There is no reason to think that anyone who was on the flight he was on is at any risk."

Texas Health Presbyterian said in a statement late Monday that it had admitted a patient into strict isolation "based on the patient’s symptoms and recent travel history." Officials said the patient was isolated soon after he came to the hospital.

Frieden said the patient was visiting family in the United States and left Liberia on an overnight flight Sept. 19. Frieden says there's no chance he could have infected anybody on the flight because he would have been checked for fever before leaving Liberia and also when he arrived in the United States.

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“But four or five days later, on the 24th of September, he began developing symptoms,” Frieden said. Ebola infection usually starts with fever and can look like malaria or influenza. He sought care on Sept. 26 and was isolated at the hospital on the 28th.

"I have no doubt that we will control this case of Ebola so that it does not spread widely in this country."

Frieden said the traveler stayed with family in the United States.

"The Texas Department of State Health Services is working with the CDC, the local health department and the hospital to investigate the case and help prevent transmission of the disease. The hospital has implemented infection control measures to help ensure the safety of patients and staff."

CDC is sending a team to Texas, including epidemiologists who are trained to track down and counsel anyone who may have been in contact with the patient while he could transmit the virus.

“We have identified all the people who could have had contact with the patient while he was infectious,” Frieden said. “It is only someone who is sick with Ebola who can spread the disease.”

Anyone who might have had direct contact with the patient after he started feeling sick — family members and health care workers, for example — will be watched for 21 days to make sure they don’t start to develop a fever or other symptoms. If they do, they’ll be immediately isolated and tested to make sure they don’t infect anyone else.

CDC officials have said that most standard hospital infection control measures should be adequate to prevent the spread of the virus. Ebola is deadly but it's not necessarily easy to catch. It doesn't travel by air but is transmitted by direct contact with the bodily fluids of someone who has symptoms, such as vomit, diarrhea or blood.

Frieden had said to expect cases of Ebola in the United States among people traveling from West Africa. The World Health Organization says more than 6,500 people have been infected, more than 3,000 have died, and the epidemic is getting exponentially worse.

"I have no doubt that we will control this case of Ebola so that it does not spread widely in this country," Frieden said. "It is certainly possible that someone who had contact with this individual … could develop Ebola in the coming weeks. But there is no doubt in my mind that we will stop it here," Frieden said.

The infected people who have been treated in the United States have all been medical workers — three missionaries working at charity-run hospitals, who have all been released, and a U.S. doctor working for WHO who is still being treated at Emory University Hospital in Atlanta.

A fifth person, another doctor who was working in Sierra Leone, is under observation at the National Institutes of Health.

"While we do not know how this individual became infected, they undoubtedly had close contacts with someone who was sick with Ebola or who died with Ebola," Frieden said.

About 200 U.S. troops have arrived in Liberia as part of a U.S. push to get the epidemic under control. President Barack Obama has pledged to send as many as 3,000 troops to the region, as well as tons of supplies and equipment and experts to help coordinate distribution.