The virus cam jump from birds to humans. Credit: © Digital Vision

The World Health Organization (WHO) has warned that an unprecedented slaughter of domestic birds must be carried out "to eliminate the large domestic reservoir" of bird flu, as the epidemic of avian influenza spreads through Asia.

This Tuesday, China announced it had a confirmed outbreak of the highly pathogenic strain of avian flu, known as H5N1, in a duck farm in Guan-gi province. Birds have been infected in many Asian countries, and people have died from the disease in Thailand and Vietnam.

The unprecedented spread of the avian influenza has been described as both "a threat to human health and a disaster for agricultural production" by the UN Food and Agriculture Organization (FAO), the World Organization for Animal Health and the WHO.

Speaking at a press conference in Geneva this Tuesday, Klaus Stöhr, project leader of the the WHO's H5N1 surveillance and scientific groups, said that at the moment there were only 11 confirmed cases of human H5N1 infection worldwide, with eight deaths, and no "epidemiologically important" reports of transmission from one human to another.

But bird flu presents a risk of evolving into an efficient and dangerous human pathogen, and its spread in developing countries is a significant control challenge, said Stöhr.

Masks and goggles

Stöhr said that slaughter of infectious flocks will continue but warned that those taking part in the slaughter must be provided with protective masks and goggles to reduce the risk of infection. This has not always happened in the slaughters during this outbreak, he said.

The only way to avert the risk of a human pandemic is to reduce the circulation of the virus in both birds and humans, he added.

"There is a window of opportunity to keep this in a box," said Stöhr. The SARS virus jumped out of the box - from birds to humans, with devastating consequences, because precautions were taken too late, he said.

Tthe WHO is confident that surveillance in China, where the SARS outbreak began, was now well equipped to identify and report cases of bird flu, primarily because SARS has similar symptoms, Stöhr said.