The Centers for Disease Control and Prevention on Tuesday confirmed the first U.S. case of coronavirus, a respiratory infection first reported in the Chinese city of Wuhan that has killed at least six and made hundreds sick.

According to Nancy Messonnier, the CDC’s national immunization and respiratory disease director, the patient is a man in his 30s who is being treated in Snohomish County, Washington, north of Seattle.

The man reportedly traveled to the U.S. from Wuhan, a city of 11 million people. Officials believe the outbreak began in a seafood and poultry market in the city, but the agency said the man has no connection to the market.

The patient arrived in the U.S. on Jan. 15 without showing any symptoms but sought medical attention when he became sick on Jan. 19. The CDC confirmed the patient, an American resident, had coronavirus after testing him. He is currently in isolation at Providence Regional Medical Center in Everett, Washington, and is in “good condition.”

The agency has deployed a team to the state to help contain the virus, which they are still studying to determine how it spreads. While the risk to the public is still low, Messonnier said health officials “expect additional cases in the U.S. and globally.”

Washington State’s Department of Health said it is working with the CDC and the Snohomish Health District to identify people the man may have come into contact with so they can be monitored for “fever and respiratory symptoms.”

The CDC says symptoms of the virus may include fever, cough, and “difficulty breathing,” which could potentially lead to more severe respiratory illness. In Wuhan, there is a current outbreak of pneumonia, which was found to have been caused by coronavirus.

Janet Baseman, an epidemiology professor at the University of Washington, said pneumonia is a “common presentation” of SARS, a type of coronavirus that spread to over two dozen countries in 2003. A “severe respiratory and pneumonia outbreak” accompanied the spread of SARS that year.

“That tipped the authorities off that they should be testing these people,” she said.

The professor, a Washington resident, said she is not worried about a single case in her state.

“If you are not going to be in an airport or airplane, nothing to worry about,” she said. “I don’t feel anyone should be frightened.”

But for those traveling, Baseman recommended taking extra “precautions" like washing hands, using disinfectant wipes, and “stepping up general hygiene.”

Hartsfield-Jackson Atlanta International Airport and Chicago’s O’Hare International Airport will reportedly begin screening for coronavirus this week, the CDC said.

Screenings have already begun at San Francisco International Airport, Los Angeles International Airport, and John F. Kennedy International Airport in New York.

Correction: In an earlier version of this article, we wrote that pneumonia was a “common presentation” of coronaviruses. We regret the error.