A deadly strain of bird flu has been detected in initial tests of several Vietnamese pigs, the Food and Agriculture Organization said on Friday, but a Vietnamese government official said they were unaware of any such finding.

"The H5N1 virus was in the nasal cavities of the pigs," said Anton Rychener, Viet Nam representative of the UN agency. He added that blood tests on the pigs had been sent to Hong Kong and results were not yet returned. The pigs had not fallen ill with the virus that has killed at least 18 humans.

The finding is alarming because pigs can become a "mixing vessel" for the flu virus. The immune system of pigs is similar to that in humans and the animals suffer from a wide variety of diseases that also infect people.

Scientists say the bird flu pathogen could swap genes with a human influenza virus inside a pig.

The World Health Organisation has said this could result in the emergence of a new subtype of virus for which humans would have no immunity.

Rychener said three or four pigs were initially positive for the virus and that he did not recall how many swine in total had been tested.

Animal health experts have been taking samples from pigs as a routine procedure where they find them raised alongside chickens.

Asked about the FAO comment, an official at the Department of Animal Health said: "We are not informed of any such finding. We know that the H5N1 is not found in the tested pigs from Viet Nam.

The official added: "If FAO puts out that statement, they must make clear where the tests have been conducted."

 

(Agencies via China Daily February 6, 2004)