A person who recently travelled to China is believed to be the first person diagnosed with coronavirus in the United States.
The news was announced by health officials, Associated Press reports.
The man returned to the Seattle area in the middle of last week after travelling to the Wuhan area, where the outbreak began.
The man is in his 30s and is in good condition at a hospital in Everett, outside Seattle.
A Brisbane man is in isolation in Australia after being diagnosed with the virus, having also recently visited family in Wuhan.
Last month, doctors began seeing a new type of viral pneumonia — fever, cough, difficulty breathing — in people who spent time at a food market in Wuhan.
More than 275 cases of the newly identified coronavirus have been confirmed in China, most of them in Wuhan, according to the World Health Organisation.
The count includes six deaths — all in China, most of them age 60 or older, including at least some who had a previous medical condition.
Officials have said it probably spread from animals to people, but this week Chinese officials said they've concluded it also can spread from person to person.