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Recent cases of bird flu outbreak indicate the H5N1 avian influenza virus may have dangerous mutations, a US bird flu expert said on Tuesday.

The virus, which has killed several domestic cats in Germany and Austria, may have acquired the ability of directly transferring from wild birds to cats and dogs, said Dr. Carol Cardona, a poultry veterinarian and professor at the University of California, Davis.

Cardona is part of a network of US researchers providing education about bird flu. Her laboratory also conducts research on avian influenza viruses focusing on the disease caused in chickens.

"Recent cases in Germany and Austria may be a dangerous sign," Cardona told Xinhua in a telephone interview.

"We have known that felids could be infected by the virus easily," she said. "Last year, tigers and leopards in a zoo in Thailand were killed by the virus after eating fresh chicken, but the German cases are different."

Generally, the H5N1 virus transfers from wild birds to poultry, and then goes from poultry to wild birds or other species, including human, according to Cardona.

But in recent cases, domestic cats were infected after eating dead wild birds or contacting with them.

"That means, the virus may have acquired the ability of directly transferring from wild birds to other species, such as domestic cats or urban dogs," she said. "It may be able to do this without the poultry."

If the virus can infect domestic cats and urban dogs, which closely contact with people in everyday life, it will pose more threat to humans, she said.

There is no evidence that the virus has accomplished the so-called "species jumping," which means it can circulate among animals other than the birds.

"But there is the possibility, so we can never underestimate the virus," she said.

Asian poultry industry must reform

The highly pathogenic H5N1 bird flu has spread from Southeast Asia to Europe, the Middle East and Africa. So far, the virus hasn't reached North or South America, but experts say its arrival is only a matter of time.

The deadly virus has killed millions of birds and more than 100 humans since it appeared 10 years ago.

It mutates, and the big fear among the world's scientists is that the bird flu virus will join the human flu virus, change its genetic code and emerge as a new and deadly flu that can even spread through the air from human to human.

If the virus has mutated into a human flu virus, it does not necessarily mean it will be as deadly to people as it is to birds, but experts say they must prepare for the worst.

According to Cardona, the world's poultry industry has suffered huge losses because of the bird flu outbreak.

"The common consumers, not knowing properly cooked chicken is safe, refuse to buy poultry products. It happens in Italy and some other European countries," she said.

And the poultry industry must reform itself to cope with the bird flu challenge, especially in Asian countries. Breeding poultry in closed henneries should be safer than outdoor feeding, Cardona said.
 
"I know that both forms exist in China and other Asian countries, indoor breeding and outdoor free-ranching," she said.

"Since the bird flu broke out about 10 years ago, no indoor hennery has been infected, while there are too many cases of infection in outdoor feeding."

"If they (outdoor poultry farms) are infected, the death rate must be 100 percent. That means a tragedy for chicken, also means huge loss and danger to humans."

(Xinhua News Agency March 15, 2006)