Three cats have tested positive for the deadly strain of bird flu in Austria's first reported case of the disease spreading to an animal other than a bird, state authorities said Monday.
The sick cats were among 170 living at an animal shelter where the disease was detected in chickens last month, authorities said.
The World Health Organization called bird flu a greater global challenge than any previous infectious disease, costing global agriculture more than $10 billion and affecting the livelihoods of 300 million farmers.
Poland reported its first outbreak of the disease, saying Monday that laboratory tests confirmed that two wild swans had died of the lethal strain.
Dr. Margaret Chan, who is spearheading WHO's efforts against bird flu, told disease experts meeting in Geneva to discuss bird flu preparations that the organization's top priority was to keep the deadly strain from mutating into a form easily passed between humans. That could trigger a global pandemic.
Since February, the virus has spread to birds in 17 new countries in Africa, Asia, Europe and the Middle East, she said.
"We truly feel that this present threat and any other threat like it is likely to stretch our global systems to the point of collapse," said Dr. Mike Ryan, WHO's director of epidemic and pandemic alert and response.
WHO spokeswoman Maria Cheng said experts hope to isolate outbreaks and establish agreements allowing international health authorities to respond quickly, testing viruses and putting in place measures to contain the disease.
In Austria, all the cats from the affected shelter have been moved to a location where they will remain under observation. The shelter has been closed, Health Minister Maria Rauch-Kallat told reporters in Vienna.
"We have decided to put all the cats in quarantine," Rauch-Kallat said. "Here they will be observed by veterinarians and experts in the coming days and weeks."
German authorities last month confirmed that a cat on the Baltic Sea island of Ruegen had succumbed to the deadly virus, which it is believed to have caught by eating an infected bird.
That would be consistent with a pattern of disease transmission seen in wild cats in Asia.
German officials have warned pet owners to keep their cats indoors and dogs on a leash in areas where the disease has been detected
Austria confirmed the nation's first case of H5N1 in a wild bird last month and has since detected several dozen cases in birds, including 29 in Styria.
According to WHO, several tigers and snow leopards in a zoo and several house cats were infected with H5N1 during outbreaks in Asia in 2003 and 2004.
Poland announced that the infected swans were found dead Thursday in Torun, about 120 miles northwest of Warsaw. Samples were being sent to Britain for further tests.
According to the latest WHO figures, the H5N1 strain has killed at least 95 people since 2003, mostly in Asia, and devastated poultry stocks. Scientists are concerned that the virus could mutate into a form easily spread between people, sparking a pandemic.
Meanwhile, a top animal health official with the Rome-based U.N. Food and Agriculture Organization said developed countries had responded slowly to bird flu, failing to control the disease in Asia and not doing enough to prepare poor countries, particularly in Africa, for its spread.
"In 2004 we said it will be an international crisis if we don't stop it in Asia, and this is exactly what is happening two years later," said Joseph Domenech, head of FAO's Animal Health Service.
"We were asking for emergency funds and they never came. We are constantly late."