Vietnam Pigs 'could Have Bird Flu'

The deadliest strain of the bird flu sweeping across Asia may have spread to Vietnamese pigs, UN scientists said today.

A representative of the UN's Food and Agriculture Organisation said that initial tests in Hanoi had found the H5N1 strain in the pigs' nasal cavities. However, the results of blood tests on the animals were still awaited and none of the animals have shown signs of becoming ill.

A spokesman for the World Health Organisation also warned that the FAO's findings were "very preliminary results" and said that its tests could have been contaminated.

The development came as the human toll from bird flu today rose to 18. The latest victims are a six-year-old girl and a 24-year-old man in Vietnam.

There is no evidence of human-to-human transmission of H5N1, but health officials fear that pigs could act as a "mixing vessel", combining human and bird flu into a new strain that is capable of spreading between people.

The immune system of pigs is similar to that of humans, and the animals suffer from a wide variety of diseases that also infect people.

But British veterinary sources stressed that the speculation should not cause undue alarm, saying that the risk of H5N1 spreading from pigs to people was not that great.

Vietnam's state media today ran articles saying that samples taken from 179 pigs in the country's northern provinces had been found to be free of bird flu.

Ten countries are battling the virus, and have culled 50 million chickens and other fowl as international health officials seek ways to contain an outbreak that has spread across half of the Asian continent.

The virus has jumped to people in Vietnam and Thailand, with health officials tracing most of those cases directly to contact with sick birds.

The WHO has said that the virus is believed to spread across regions via migratory birds, but exactly how it moves is not clearly understood.

Countries fighting the outbreak are Thailand, China, Vietnam, Laos, Cambodia, Indonesia, Japan, South Korea, Pakistan and Taiwan.

However, the strain afflicting Pakistan and Taiwan is milder, and is not considered to be dangerous to humans.