CDC on Tuesday announced that a Washington state man has been diagnosed with a new coronavirus that is spreading throughout Asia, marking the first confirmed U.S. case of the virus.

Details on the virus

Reports of the infection first surfaced in early December 2019 among people in China's Wuhan province. Chinese state media earlier this month announced that the cause of the illness "is believed to be a new type of coronavirus," and said "more scientific research is needed for further understanding."

The World Health Organization (WHO) in a statement explained that "[c]oronaviruses are a large family of viruses that range from the common cold to SARS." The organization said, "Some cause less-severe disease, some more severe. Some transmit easily from person to person, while others don't."

The Chinese outbreak's origin has been connected to a now-closed large live seafood market that also sold exotic animals, leading experts to initially believe the disease infected humans through exposure to animals.

However, reported cases of the virus climbed quickly and soon extended beyond China's Wuhan province. Chinese state media on Wednesday reported that officials have confirmed 473 cases of the virus—up from 291 confirmed cases that had been reported as of Tuesday. Officials on Wednesday also said there have been 17 reported deaths linked to the virus, up from six that had been reported as of Tuesday.

Reported cases involve patients in China, Japan, Korea, Thailand, and now the United States, and include patients who had not visited the Wuhan province or had contact with animals. The virus' quick and widespread transmission led Chinese health authorities to confirm that the virus also can be spread between humans. In addition, Chinese authorities said one patient is believed to have infected up to 14 health professionals at one hospital, suggesting the virus might be spread more easily than previously thought.

According to WHO, the main symptoms of infection from the Wuhan coronavirus, called 2019-nCoV, are fever and lesions in both lungs. Some patients also have reported difficulty breathing, WHO said.

CDC announces 1st case of the virus confirmed in US

On Tuesday, CDC announced that a man in his 30s who is a resident of Washington's Snohomish County developed symptoms of the virus after he returned to the United States on Jan. 15 from a trip to a region near Wuhan. At the time of his return, the man presented no symptoms of the virus and U.S. airports had not been screening travelers for possible infection.

CDC officials said the man, who read about the virus online, began to experience pneumonia-like symptoms shortly after his return and on Sunday sought care at a clinic in Snohomish County. The man informed providers about his recent trip to a region near Wuhan and underwent tests for the virus, which confirmed the man was infected with the new coronavirus.

The man was hospitalized at Providence Regional Medical Center-Everett and is in stable condition with a mild case of pneumonia. A hospital spokesperson said providers are monitoring the man in a special isolation unit "for at least the next 48 hours." According to the Washington Post, officials said they're monitoring the patient to be extra cautious, not because his symptoms are severe.

Officials also said they believe it is unlikely the man transmitted the virus to others. John Wiesman, Washington's Secretary of Health, said, "The man who tested positive acted quickly to seek treatment," adding, "We believe the risk to the public is low."

Still, health workers currently are trying to identify people who may have had contact with the patient and are notifying passengers on the man's return flight who might have been exposed to the virus.

CDC, global health agencies respond

CDC and other U.S. agencies are working to monitor and contain the virus' potential spread in the United States.

For example, federal officials on Tuesday announced that they will now screening for symptoms of the virus at five major U.S. airports. Federal officials on Friday and Saturday began screening passengers arriving from Wuhan at Los Angeles International airport, New York's Kennedy International Airport, and San Francisco International airport. Officials said over the next few days they will expand the screenings to include Hartsfield-Jackson Atlanta International airport and Chicago O'Hare International airport. Officials from CDC and the Department of Homeland Security said they are working with airlines and airports to ensure all travelers arriving in the United States from Wuhan are redirected so their first arrivals in the country are to an airport where screenings are taking place.

Nancy Messonnier, director of CDC's National Center for Immunization and Respiratory Disease, said she expects the United States likely will not see many cases of the new virus, though she does expect more. "This is an evolving situation and … we do expect additional cases in the United States and globally," she said.

President Trump on Wednesday said the United States has the situation "totally under control." Trump said he is "not at all" concerned about a potential pandemic of the virus, noting that U.S. officials have a plan in place to address the issue.

Elsewhere, authorities are taking measures to prevent the spread of the virus, particularly as the Lunar New Year, which is China's largest holiday for travel, approaches. For example, Wuhan on Tuesday announced the city is canceling upcoming Lunar New Year celebrations, banning tour agencies from taking people out of Wuhan, and increasing the number of thermal monitors and screening areas for the virus in public areas. Wuhan authorities also have banned large public gatherings and performances and ordered locals to wear masks in public.

In addition, China said it plans to implement measures to manage the outbreak, including mandatory reporting of cases of the virus. The country has faced criticism for allegedly delaying reporting the outbreak.

US hospitals prepare for cases 

Meanwhile, U.S. hospitals are taking steps to help them quickly identify whether patients are infected with the virus and prevent the virus' spread, William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center (VUMC) in Nashville, said.

For example, VUMC in Nashville on Monday changed its electronic prompts to ensure providers ask patients who come to the hospital with a fever or respiratory symptoms whether they have recently visited China or they have come in contact with anyone who has traveled to the China (Qian/Young Lee, Reuters, 1/22; Caryn Rabin, New York Times, 1/21; Sun/Bernstein, Washington Post, 1/21; Aratani/Sun, Washington Post, 1/21; McKay/Deng, Wall Street Journal, 1/22; Baumgaertner, Los Angeles Times, 1/21; Hernández, New York Times, 1/22; Chalfant, The Hill, 1/22; Alper, Reuters, 1/22; Zraick, New York Times, 1/21; Qin/Wang, New York Times, 1/22).