A man in Washington state has been diagnosed with the mysterious coronavirus virus, the first case confirmed in the United States since the illnesses first appeared in China last month and which has killed at least six people and sickened hundreds more in Asia, according to people familiar with the investigation.

The man is in stable condition. He arrived in the United States last week, before federal health officials began screening travelers from the central Chinese city of Wuhan at Los Angeles, San Francisco and New York's John F. Kennedy international airports.

The outbreak has grown rapidly in recent days, with authorities in China reporting cases in multiple cities. The World Health Organization is meeting tomorrow to decide whether to declare the outbreak a public health emergency.

The Centers for Disease Control and Prevention is expected to announce details about the U.S. case in an afternoon news conference.