The man returned to the Seattle area last week after travelling to the Wuhan area, where the outbreak began.
The man is in his 30s and is said to be in good condition at a hospital in Everett, outside Seattle.
The US is the fifth country to report seeing the illness, following China, Thailand, Japan, and South Korea.
Later on Tuesday the US Centre for Disease Control and Prevention said it expects to see more cases of the Wuhan coronavirus in the United States.
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 Organization.
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.
A Brisbane man being tested for the virus was released from isolation at his home on Tuesday.
The man flew into Brisbane earlier in January after visiting family in Wuhan.
He shows no ongoing symptoms and test results are expected in coming days, Queensland Health said.
Biosecurity measures have been ramped up for flights into the country from China, and the city of Wuhan in particular.
“A number of people have been tested in Australia and found to be negative,” federal Heath Minister Greg Hunt told Sky News on Wednesday.
Australia receives three flights from Wuhan per week which would be monitored closely, he said.
“(Flights) will be met by biosecurity officers, information given to passengers and the biosecurity officers will be accompanied by health officers,” Hunt told the ABC.
“They do have the capacity because of the measures taken to bring people directly to hospital if that were required.
“But we expect that any passengers that do have issues will self-report because it’s in their own interests but if not, then there are strong powers.”
Chief Medical Officer Brendan Murphy has urged anyone who has come from Wuhan and develops flu-like symptoms to seek medical attention.
“The risks really at present remain particularly focused on people coming from that region of China, particularly the city of Wuhan,” Murphy told the ABC.
“That’s why we have ramped up biosecurity measures meeting those three direct flights from Wuhan a week.”
He said there is no evidence that the virus is present in Australia.
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