A Wuhan evacuee who was on the flight that landed this week at March Air Reserve Base in Riverside County has been quarantined after attempting to leave the base, the same day the World Health Organization declared a “global emergency.”

Riverside County Health Officer Dr. Cameron Kaiser issued the order requiring the passenger to stay at the base for the entire incubation period, up to 14 days, or until otherwise cleared, officials said in a news release Thursday, Jan. 30. The order was made because of the unknown risk the person poses to the public if they left before being fully evaluated, officials said.

The passenger will remain on the base until his or her health status is confirmed. All other passengers from the flight are still on the base and continue to be evaluated for symptoms, including fever, cough and other respiratory symptoms, officials said.

The World Health Organization declared the coronavirus outbreak as a global emergency Thursday after a spike in cases over the past week.

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China has reported more than 7,800 cases, including 170 deaths from the respiratory illness — which belongs to the same family as the virus that causes severe acute respiratory syndrome, or SARS. The new virus has now infected more people in China than were sickened there during the SARS outbreak in 2002-2003.

Both are from the coronavirus family, which also includes viruses that can cause the common cold.

Since the new virus surfaced in December, there have been no deaths outside of China, but cases of infection have been reported in 18 other countries, including six in the U.S., with one each in Los Angeles and Orange counties.

WHO defines a global emergency as an “extraordinary event” that constitutes a risk to other countries and requires a coordinated international response. Previous global emergencies were declared during the emergence of the Zika virus in the Americas, the swine flu pandemic, and polio.

China has cut off access to the central city of Wuhan, epicenter of the outbreak, and 16 other cities to prevent people from leaving and spreading the virus further. Several U.S. and international airline carriers have suspended, or reduced flights, in an out of the region.

The passengers on the U.S. government-chartered flight, originally bound for Ontario International Airport but was redirected late Tuesday. touched down in Riverside County Wednesday morning are still going through an evaluation. There is no indication that any of the passengers are sick, according to Yaoska Machado, a Riverside County spokesperson. The quarantined passenger has been cooperating, Machado said.

More information on why the plane was rerouted was not available Thursday, a State Department spokesperson said in an email.

Seating on the flight out of Wuhan was offered to Americans on a reimbursable basis, but a further breakdown of the passengers was not available.

Priority was given to vulnerable individuals at higher risk, including small children, older adults and people with other health conditions. If the individuals were with family members who were not at greater risk, the families were allowed to travel together, the State Department spokesperson said.

The 195 passengers who arrived Wednesday remain in voluntary isolation for 72 hours before they can move on to their next destination, officials have said.

Passengers, including children whose ages range from 1 month to teens, went through two screenings in China and were monitored during the flight, officials said. They were screened again in Alaska during a fueling stop and were approved to continue to March ARB.

Officials in Alaska said all passengers passed health screenings. One person with a fever in Wuhan did not board the plane for the U.S., officials said.

A Centers for Disease Control and Prevention team will continue to check the group for symptoms every 12 hours over the 72-hour period, officials said.

The arrival of the passengers has not impacted operations at the base, said Linda E. Welz, March ARB spokeswoman.

“All the stores are open, people can come get their ID cards, tickets for Disneyland — nothing has been affected,” Welz said.

The passengers are staying in two buildings that are part of The March Inn near the base’s parade field, Welz said. The area has been cordoned off and is being monitored by security and medical personnel, she said.

A town hall was held Thursday morning for the passengers and more meetings are planned for the people who work on the base, Welz said.

Experts say there is significant evidence the virus is spreading among people in China and have noted with concern several instances in other countries — including the United States, France, Japan, Germany, Canada and Vietnam — where there have also been isolated cases of human-to-human transmission.

Health officials on Thursday reported the first U.S. case of person-to-person spread of the virus. The man is married to a Chicago woman who got sick from the virus after she returned from a trip to Wuhan.

The other five U.S. cases were travelers who developed the illness after returning to the states from China.

The virus is believed to have come from a wholesale market where vendors legally sold live animals from stalls in close quarters with hundreds of others. Nearly two decades ago, SARS had a similar origin story, jumping from bats to Asian palm civets, and then to humans involved in the wildlife trade.

Coronaviruses are a large family of viruses that circulate mostly among animals, including camels, cats and bats. Common symptoms in an infected human include a fever, cough and shortness of breath or difficulty breathing. Common symptoms in an infected person include a fever, cough and shortness of breath or difficulty breathing.

The Associated Press contributed to this report.

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