By Sui-Lee Wee BEIJING (Reuters) - Several governments in Asia have ordered tougher screening of air travellers from China in an effort to contain a possible spread of a new strain of bird flu that has killed 23 people in the mainland and infected one visitor from Taiwan. The H7N9 virus has infected 109 people in China since it was first detected in March. The Geneva-based World Health Organization said it has no evidence so far of sustained transmission between people but added that this strain was more easily transmitted than an earlier, more deadly H5N1 strain that has killed hundreds around the world since 2003. Taiwan, which reported the first H7N9 case outside of mainland China on Wednesday, said it would test air travellers for bird flu if they displayed suspicious symptoms. The island's first victim, a 53-year-old man who had returned from a visit to China's eastern city of Suzhou days before, was being treated in hospital. He said he had not had any contact with poultry. Vietnam began screening temperatures of all visitors at its airports, officials said on Thursday, while Japan said it will allow airports and seaports to make "thermographic inspections" of travellers from China starting in May. Thai Health Minister Pradit Sintawanarong said the country must step up precautions, adding that the health ministry will soon submit a plan to the prime minister to address the problem. "From our assessment of the situation, there is a chance that the H7N9 virus may spread to Thailand," Sintawanarong said. The moves came a day after a WHO expert said the H7N9 strain is "one of the most lethal" of its kind. An international team of scientists led by the WHO and the Chinese government said on Wednesday they were no closer to determining whether the virus might become transmissible between people after a five-day investigation in China. Singapore's health ministry said its healthcare institutions "remain on heightened alert". TAIWAN AIRLINES TANK Shares in Taiwan's airlines fell sharply on Thursday after news of the island's first bird flu victim sparked worries that the outbreak could spread and hurt travel. China Airlines shares shed 2.2 percent, the stock's worst daily loss since April 8. Eva Airways fell 2.4 percent to close at its lowest in about two weeks. Both underperformed the main TAIEX index, which finished flat on Thursday. However, most Asian airlines said they had not experienced a noticeable change in bookings to China. Raj Tanta-Nanta, a vice-president for investor relations at Thai Airways International, said the number of passengers to destinations in China had declined slightly but the national carrier had not cancelled flights to China. Thai AirAsia also said it is not trimming flights. "We're not cancelling flights and that may be because we fly to Yunnan, which has not faced bird flu disease," Chief Executive Tassapon Bijleveld told Reuters. Still, the current spate of cases has sparked reminders of the impact on travel from SARS, or severe acute respiratory syndrome, which killed 774 people, mostly in China and Hong Kong in 2003. Japan's Sharp Corp. urged its employees to "take extra precaution" when visiting China, telling them on Monday to avoid contact with birds, wash their hands and wear a mask if they develop cold or flu symptoms. Many companies across Asia that have operations in China, including India's Tech Mahindra Ltd, said they were evaluating the situation but had not yet placed any restrictions on employees there. POULTRY IMPORTS BANNED Some countries tightened screening of poultry imports from China, where some bird samples had tested positive for H7N9. Vietnam banned poultry imports from China in early April, its agriculture ministry said. The Philippines, which has banned poultry imports from China since 2004, is tightening quarantine measures on all poultry products, said Davinio Catbagan, assistant secretary for livestock at the agriculture department. Manila has also strengthened measures to prevent the entry of smuggled poultry and other poultry products such as pigeons, Peking ducks and chicken, especially those coming from China, Catbagan said. "The department had been notified that there are businessmen in the Philippines who illegally imports these products, which may have been contaminated by the highly pathogenic H7N9 virus and are now openly served in five-star hotels and well-known Chinese restaurants in the country," Catbagan said. (Additional reporting by Pairat Temphairojana, Panarat Thepgumpanat and Manunphattr Dhanananphorn in BANGKOK, Kaori Kaneko and Tim Kelly in TOKYO, Clare Jim in TAIPEI, Kevin Lim in SINGAPORE, Sui-Lee Wee in BEIJING, Rosemarie Francisco in MANILA, Prak Chan Thul in PHNOM PENH, Prashant Mehra and Harichandan Arakali in NEW DELHI, Kazunori Takada in SHANGHAI, Hanoi Newsroom in HANOI, Jonathan Thatcher in JAKARTA, Writing by Sui-Lee Wee; Editing by Ken Wills) | 
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