The government issued orders Monday for doctors and nurses to board aircraft from Mexico at Narita airport starting Wednesday to check passengers and crew for infection of a deadly new virus that combines swine, avian and human influenza.

All arrivals will be required to fill out health questionnaires, and doctors will check people who complain of flulike symptoms while they are still on board, Akimori Mizoguchi of the health ministry said. Those without symptoms will not be tested as a check would be unlikely to detect the flu in an early stage of infection, he added.

Contact information and test results for those without symptoms or who test negative will be sent to local health centers, which will keep in touch with the recent arrivals, he said. If no symptoms occur within 10 days of leaving Mexico, there is little risk of infection, he added.