HANOI, Jan. 27 (Xinhuanet) -- There has been evidence of transmissions of bird flu virus to humans in Vietnam, local media quoted sources from the country's Hygiene and Epidemiology Institute on Tuesday.

    The institute has determined that most of human deaths caused by flu type A subtype H5N1 lived in bird flu-hit localities. A total of 18 local people have died of flu type A.

    Besides, laboratory tests, both domestically and abroad, have showed that strains of virus found in local people are also found in sick chickens. However, there is no verification of a possible link between bird flu and two deaths in Ho Chi Minh City and southern Kien Giang province.

    Both local and foreign scientists have yet to find out the way bird flu viruses transmit to persons. There is also no evidence ofH5N1 transmissions among humans.

    However, Trinh Quan Huan, director of the Preventive Medicine Department under Vietnam's Health Ministry, noted H5N1 might jump from persons to persons, given that several local people within a family have contracted flu type A.

    Among 50 acute pneumonia cases caused by flu viruses, seven have been confirmed to be infected with H5N1, of whom six have died. Others have not received final testing results or been confirmed to contract common pneumonia.

    The 50 flu patients come from 14 localities, including Hanoi and Ho Chi Minh City. Now, 31 are under treatment in the two cities and the southern province of Kien Giang.

    According to the World Health Organization (WHO), of all the avian flu viruses, which normally cause infection in birds and pigs only, the H5N1 strain may have a unique capacity to cause severe disease, with high mortality, in humans.

    When humans are infected by human and avian flu simultaneously,a new flu virus subtype might emerge, carrying sufficient human genes to allow person-to-person transmission, WHO warned.

    The organization has called for bird flu-stricken countries andregions to cull infected and exposed fowls to prevent further spread in bird populations and reduce chances for human infection.Enditem