Due to a swine flu case suspected by China's Ministry of Health, authorities are urging passengers onboard May 7's Air Canada flight AC29 (arrived in Beijing on May 8) to contact their local center for disease control and prevention or other relevant public health agencies.

Despite the best efforts so far, while some passengers who shared the same flight with the patient have been tracked down by health authorities here in China, but authorities are still experiencing difficulties in locating the remaining passengers.