(Reuters) - A university student being treated for a respiratory illness in Texas after traveling to Wuhan, China, is being tested for the newly discovered coronavirus that has killed 18 people in China, state and local officials said on Thursday.

Travellers wearing masks arrive on a direct flight from China, after a spokesman from the U.S. Centers for Disease Control and Prevention (CDC) said a traveller from China had been the first person in the United States to be diagnosed with the Wuhan coronavirus, at Seattle-Tacoma International Airport in SeaTac, Washington, U.S. January 23, 2020. REUTERS/David Ryder

If the patient, who has not been publicly identified, tests positive for coronavirus it would mark the second known U.S. case of the illness, which has already sickened an estimated 650 people worldwide. The first U.S. case was diagnosed in Washington state.

“Public health officials in Brazos County are investigating a patient who meets the definition of a potential case of the 2019 novel coronavirus. The patient got sick with a respiratory illness within two weeks of travel in Wuhan, China,” Texas health officials said in a statement.

“The patient is being isolated at home in accordance with recommendations from the Centers for Disease Control and Prevention as the investigation continues to determine whether this is a case of novel coronavirus,” the health officials said.

A CDC spokeswoman said the agency was coordinating testing of the individual, but cautioned that it could be a false alarm.

“Because it is cold and flu season and many people are suffering from respiratory illnesses, we expect there will be more travelers who fall under the CDC’s testing guidance. DSHS will promptly announce any confirmed novel coronavirus cases. We won’t provide details on negative tests,” the spokeswoman said.

Although Texas and CDC officials did not provide any identifying information about the patient, Texas A&M University said it had been notified by local health officials that the patient was a student there.

“Officials have described the immediate health risk to the campus community as low,” the university said in a statement.

Earlier this week a Washington state man who had traveled to the Wuhan region of China was diagnosed with coronavirus, becoming the first confirmed U.S. case. He is reported to be in satisfactory condition.

The coronavirus, which causes respiratory symptoms similar to a cold or flu, has been linked to a seafood market in Wuhan, the largest city in central China with a population of about 11 million. That market has since been shut down.

Though China has put millions of people on lockdown over the outbreak and U.S. officials have begun screening passengers arriving from that region, the World Health Organization said on Thursday it was too early to declare a global health emergency.