The city of Wuhan, China, is racing to contain the potential spread of a deadly new strain of virus that has now infected nearly 450 people. Over the weekend, the number of cases of the "2019 novel coronavirus" or "2019-nCoV" quadrupled - and on Tuesday, U.S. health officials confirmed the first case in the United States, in a man in his 30s who had recently traveled from Wuhan, China, to Seattle.
On Monday, a Chinese scientist confirmed that there can be human-to-human transmission of the respiratory illness.
Several U.S. airports have begun screening passengers from China to prevent the virus from spreading further. Here's what you need to know:
What is a coronavirus?
Coronaviruses are a large group of viruses that can cause illnesses as minor as a cold, or as serious as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS), according to the World Health Organization. They often present with pneumonia-like symptoms.
The viruses are transmitted from animals to humans - the virus that causes SARS, for example, was transmitted to humans from a cat-like animal called a civet. But in some instances, as appears to be the case with this new strain of coronavirus, they can also be transmitted between humans.
The World Health Organization said there are multiple known coronaviruses circulating in animals that have not yet been transmitted to humans.
How did the new strain start?
The outbreak began in Wuhan, a city of 11 million people. Many of the patients have reportedly been linked to Hua Nan Seafood Wholesale Market, a large seafood and animal market in the city, according to CBS News' Ramy Inocencio. But a rising number of people have apparently contracted the virus without exposure to the market, according to Chinese officials.
The market was closed on January 1, 2020 for "environmental sanitation and disinfection," according to the World Health Organization.
Ramy Inocencio and Grace Qi contributed to this report.
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