Coronavirus case confirmed in California, takes US total to 13

The 13th case of coronavirus in the United States was detected in California in a person under federal quarantine after returning from Wuhan, China, the US Centers for Disease Control and Prevention (CDC) said on Monday.

The adult patient was among US nationals evacuated from Wuhan, the epicenter of the disease, who were under mandatory quarantine for 14 days at Marine Corps Air Station Miramar, near San Diego, the CDC said in a statement.

The individual was taken to the University of California San Diego Medical Center for observation and isolation and is "doing well," the hospital said in a statement.

A spokesman for the medical center declined to comment on the report, but said the hospital would soon be releasing a statement.

"CDC is conducting a thorough contact investigation of the person who has tested positive to determine contacts and to assess if those contacts had high risk exposures," the CDC said in a statement, without giving further details.

Some 540 U.S. nationals have been evacuated from Wuhan and flown to the Miramar base where they are subject to the CDC’s first public health quarantine in 50 years.

The individual was among four patients taken to the UC San Diego Medical Center for further evaluation last week.

On Sunday, the CDC said all four patients tested negative for the virus and they were discharged and returned to federal quarantine at MCAS Miramar, the medical center said.

On Monday morning, CDC officials advised San Diego Public Health that further testing revealed one of the four patients tested positive for coronavirus and was returned to UC San Diego Health until cleared by the CDC for release.

One additional patient from MCAS Miramar was transported to UC San Diego Health on Monday afternoon for evaluation for coronavirus and will remain admitted until test results are confirmed by the CDC, the medical center said.

"Both patients are doing well and have minimal symptoms," the medical center said.