Airline passengers are being checked for symptoms of coronavirus, as the first US cases of the respiratory illness have been reported.

NPR reports┬áthat public-health officials are monitoring travellers for signs of illness at San Francisco International, Los Angeles International Airport, John F. Kennedy International Airport, Chicago O’Hare International Airport, and Hartsfield-Jackson Atlanta International Airport.

The previously unknown strain of coronavirus originated in the city of Wuhan, China, has killed at least 25 people, and has spread to other parts of China and other nations in Asia. The first known US cases of the illness were confirmed in Chicago and Washington state this week.

Chinese health officials have ordered a general quarantine of Wuhan and several other cities in an attempt to slow the spread of the disease. Flights to and from Wuhan have also been suspended.

Airport screening for the disease generally starts with taking the temperature of travellers suspected of being sick. However, some health experts, including the World Health Organization, call such resource-intensive testing ineffective.