New York (CNN Business) The Allied Pilots Association, a union representing 15,000 American Airlines pilots, has sued the company to halt the carrier's U.S.-China service, citing "serious, and in many ways still unknown, health threats posed by the coronavirus."

The union asked the court in Dallas County for a temporary and immediate restraining order halting the flights as the virus spreads.

"The safety and well-being of our crews and passengers must always be our highest priority — first, last, and always," APA President Capt. Eric Ferguson said in a statement. "Numerous other major carriers that serve China, including British Airways, Air Canada, and Lufthansa, have chosen to suspend service to that country out of an abundance of caution."

The coronavirus, a potentially fatal respiratory disease, first emerged in Wuhan, China in early December and has since spread across China and appeared in some other countries , including the United States, Japan and India. The World Health Organization has declared the coronavirus epidemic a public health emergency of international concern, after an emergency committee convened Thursday in Geneva.

The current number of coronavirus cases in China has exceeded the number of SARS infections worldwide during the 2002-2003 epidemic. As of Thursday, there are over 8,000 confirmed cases of Wuhan coronavirus in mainland China. The death toll is 171.

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