At least one person in the United States is infected with the mysterious pneumonia-like virus that’s killed at least six people and sickened some 300 others since the illness was first reported in the Chinese city of Wuhan.

The case of the new coronavirus was confirmed in a man in Seattle, Washington. The man, who is in his 30s, arrived in the U.S. last week before officials with the Centers for Disease Control and Prevention (CDC) and the U.S. Customs and Border Protection (CBP) announced “enhanced health screenings” for airline passengers arriving from or traveling through the Wuhan province. San Francisco International Airport, John F. Kennedy International Airport and Los Angeles International Airport all began the initiative on Jan. 17.

CDC ANNOUNCES 'ENHANCED HEALTH SCREENINGS' AT 3 MAJOR US AIRPORTS

A traveler wears a face mask as she sits in a waiting room at Beijing West Railway Station in Beijing, Tuesday, Jan. 21, 2020. (AP Photo/Mark Schiefelbein)

The patient, who was not identified, is a resident of the U.S. and is in stable condition, CDC officials said during a Tuesday news conference. The patient is isolated at Providence Regional Medical Center in Everett, Wash., and poses "very little risk" to medical staff and the public, officials said. The man was reportedly aware of the outbreak affecting Wuhan before falling ill and proactively reached out to state health officials when he began experiencing symptoms, which have been reported to include fever, cough, and shortness of breath.

The patient did not arrive on a direct flight from Wuhan, meaning people on more than one flight may have been exposed to the illness, which officials this week confirmed is transmissible between humans. Officials are now working to determine who may be at risk, Dr. Scott Lindquist, the Washington State epidemiologist for communicable diseases, said during the news conference.

Workers spray antiseptic solution on the arrival lobby amid rising public concerns over the possible spread of a new coronavirus at Incheon International Airport in Incheon, South Korea. (Suh Myung-geon/Yonhap via AP)

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Confirmation of human-to-human transmission has sparked fears that a person infected with the virus and experiencing the most severe stage of infection could be a super-spreader —  someone who transmits the virus to a considerable more amount of people than the average infected person, the South China Morning Post reported. Coronavirus can cause a range of illnesses, from the common cold to Severe Acute Respiratory Syndrome (SARS) — the latter of which also began in China and infected some 8,000 people during a 2002-2003 outbreak. At least 770 died after it spread to other cities and countries across the world. At the time, international travel in combination with a few super-spreaders facilitated the massive outbreak, according to one report. 

The current coronavirus outbreak has now affected five countries including the U.S. In addition to China, officials in Thailand, South Korea, and Japan have also reported cases, according to the CDC.