CDC sends team to Washington state after virus case

"When person-to-person spread has occurred with SARS and MERS, it is thought to have happened via respiratory droplets produced when an infected person coughs or sneezes, similar to how influenza and other respiratory pathogens spread," the CDC said.

"Both MERS and SARS have been known to cause severe illness in people. The situation with regard to the (current virus) is still unclear. While severe illness, including illness resulting in a number of deaths has been reported in China, other patients have had milder illness and been discharged."

In 2003, the SARS outbreak resulted in about 8,000 cases worldwide and killed about 700 people, health officials said.

In response to the current virus, the CDC said it's working with local hospitals and the WHO to track the disease. Travelers from Wuhan are screened at major US airports on both direct and connecting flights.

In Canada, five residents of Quebec are under hospital observation for possible exposure to the virus. All recently traveled to China, but none have been confirmed to be infected, the Montreal Gazette reported.

"We're being careful," Dr Horacio Arruda told the newspaper.

The Yale New Haven Health System in Connectictut, which includes hospitals in nearby Bridgeport, Greenwich, New London and in Westerly, Rhode Island, now screens patients with respiratory infections to determine if they've traveled to China two weeks before becoming ill, the New Haven Register reported.

Other hospitals in the US follow similar practices, including those in Dallas.

Dr Wendy Chung, chief epidemiologist at Dallas County Health and Human Services, said she is in regular contact with area hospitals and doctors to update them about what's known about the virus so far. Area doctors ask each patient for a detailed travel history, the Dallas Morning News reported.

"The situation is evolving, and we continue to try and prepare in the appropriate ways," Dr Philip Huang, director of Dallas County Health and Human Services, told the newspaper.

Fever is the most common indicator of infection, but it appears some infected with the new virus strain don't run a high temperature. That could make infection harder to detect.

"If this virus can be transmitted without causing fever, then it's easier for the infection to travel globally because it can simply stay under the radar for a while," Ramanan Laxminarayan, director of the Center for Disease Dynamics, Economics and Policy in Washington, told Bloomberg News.

In the US, concern about the new strain of the coronavirus is playing out against a severe flu outbreak that the CDC said has killed 39 children so far in the 2019-20 flu season.