(Agencies)
Updated: 2004-02-23 11:10

The World Health Organization (WHO) sought on Friday to calm fears that the deaths of two cats in Thailand from bird flu could signify an increased danger to humans from the killer virus.

Thai scientists have reported traces of the H5N1 virus, which has killed 22 people in Thailand and Vietnam and triggered the culling of millions of chickens, in two dead cats which lived in a house near an infected farm.

The discovery triggered concern that the disease was spreading rapidly between species, increasing the risk of humans being exposed to it.

"While conclusions are premature...infection in cats is not considered likely to enhance the present risk to human health," the United Nations' health agency said on its Web Site .

Unlike other mammals such as pigs, seals and whales, cats had not been seen as susceptible to avian viruses, with the only previously known cases being those of animals deliberately infected in a laboratory.

But even if tests currently underway confirmed the Thai scientists' findings, it was highly unlikely that cats would prove to be easily infected and such cases would remain rare, WHO added.

Besides killing humans and millions of wild and farmed birds across Asia, the H5N1 strain showed earlier this week that it can jump to other species after a rare clouded leopard at a zoo near Bangkok was confirmed as dying of bird flu.

VIRUS "MIXING BOWL"

But reports earlier this month that the virus had spread to pigs, with an immune system similar to humans', turned out to be false.

Although the virus does not appear highly infectious for humans, health officials are worried that it could "mate" with a normal human flu strain to create a new highly dangerous bug against which people would have few defenses.

WHO said that unlike pigs, which can be infected at the same time with both the human and bird flu strains, cats could not play the role of "mixing-bowl" for a new super virus, such as the one that killed up to 50 million people world wide in 1918.

"Nor is it (confirmation of the cats' infection) considered likely to influence the future evolution of the outbreak in humans in any significant way," WHO added.

Nevertheless, authorities must be on guard against any further signs that the virus was spreading to other animals.

"Reporting by veterinarians of suspected or confirmed cases...as happened in the present situation, is a key component of this continuing vigilance," it added.