Mystery case heightens concern in US

Woman gets coronavirus infection of unknown origin, but governor calm

California Governor Gavin Newsom has said that he is confident the state can track and contain the possible spread of the coronavirus, despite the state having reported the first case of "community transmission" in the United States.

Prior cases in the US involved those who had traveled to China or had close contact with a spouse who recently returned from overseas. A newly discovered case in Solano County, northeast of San Francisco, involves a woman who has not been in contact with a known carrier or traveled abroad.

The governor said on Thursday that California officials are working closely with the US Centers for Disease Control and Prevention, or CDC. He stressed that the effort to limit the spread of the new strain of the virus is well funded.

Medical staff caring for the California woman with the first US case of novel coronavirus of unknown origin were unable to get her tested for five days because she had not traveled to outbreak-hit regions, a lawmaker revealed on Thursday.

In a congressional hearing, Representative Ami Bera said the patient was admitted to hospital on Feb 19 and quickly placed on a ventilator.

The same day, her doctors asked to submit a sample for a coronavirus test to federal authorities.

But it was not until Feb 23, after her condition had worsened, that there was "an insistence and a strong push and ultimately the patient did get tested", added Bera, a doctor who once worked at the same hospital.

He said he learned of the case details from former colleagues.

It took a further three days for the positive result to return, and the CDC on Wednesday declared it the first suspected case of community transmission.

This means the source of infection is unknown, a sign that the pathogen is no longer contained.

If confirmed, the development represents a new and more complicated challenge in the battle against the virus in the US.

In response to the Solano County case, California health officials have begun tracking down people who may have come in contact with the Solano County patient to halt the further spread of the virus.

Newsom said the CDC will send 10 specialists to California to interview those who may have come in contact with the patient.

Sonia Angell, director of the California Department of Public Health, said there is no known connection between the new case and Diamond Princess cruise ship passengers who were exposed to the virus overseas and quarantined at a military base in Solano County.

"The (Solano County) patient had no known exposure to the virus through travel or close contact with a known infected individual," she said.

Infections could increase

Before the Solano County case, all 59 cases in the US were traced to people who had traveled abroad or had been in contact with those who had visited China.

The prior cases included 14 people who had traveled in China, or their spouses had; three people who were evacuated from Wuhan in China, and 42 US passengers on the Diamond Princess.

The number of cases in the US is small, but infections could increase rapidly and mirror the outbreaks in Italy or South Korea, a researcher warned.

"It's possible to say we will suddenly have 20 or 30 cases from one particular place," Jeffrey Klausner, an adjunct professor of epidemiology at UCLA, told the Daily Beast. "People should expect that, but people should not be overly concerned."

The flu season, which started in September, has killed about 10,000 people so far in the US.

Scott Reeves in New York and Agencies contributed to this story.