Veterinary workers in China are monitoring domestic animals after Indonesia reported that avian influenza had been detected in a large number of cats.

The discovery has heightened concerns about a virus that experts had thought was basically infecting chickens, ducks and other fowl.

"We are surprised to hear that so many cats were discovered to have the virus," Wang Changjiang, a veterinary official with the Ministry of Agriculture, told China Daily.

"We believe it was a sporadic case, but it alerts us to expand monitoring scope."

The official did not specify when the ministry would increase monitoring efforts, or what animals would be targeted.

The ministry has not received any report of bird flu infection among dogs and cats in China; nor among pigs, which have been on a check list along with fowls and wild birds since 2004, he said.

A survey by Chairul Anwar Nidom, a scientist at Airlangga University in Surabaya, found H5N1 antibodies in 20 percent of 500 stray cats near poultry markets in four areas in Java, including Jakarta. Another case of infection was found in an area of Sumatra where there had been recent human H5N1 cases or outbreaks of the disease in poultry.

The survey said the findings suggested the cats had probably been infected because they ate infected poultry, according to the report.

Wang said he had heard about cat infections outside China, but not in such massive numbers. He said scientists have yet to identify whether dogs or cats are susceptible to bird flu.

In another case in Indonesia, Ngurah Mahardika, a virologist at Udayana University, surveyed pigs and domestic animals in Bali between September and December last year and found the virus in two dogs and a cat.

The Indonesian surveys added to worries about the virus which has killed 164 people since late 2003 and has flared again with a string of human H5N1 cases in Indonesia and the virus spreading among poultry in Vietnam, Thailand and Japan.

It is not known how efficiently domestic animals can pass the virus on to humans, or other mammals.

"The increase in the number and species of affected domestic animals may add to the risks of bird flu being transmitted to humans," Wang said.

Reuters contributed to the story

(China Daily 01/31/2007 page1)