Article on Bird Flu Criticizes Effort to Monitor Cats and Dogs

By LAWRENCE K. ALTMAN
Published: April 6, 2006
http://www.nytimes.com/2006/04/06/world/europe/06cat.html?_r=2&th&emc=th&oref=slogin&oref=slogin

Five leading European scientists are criticizing officials involved in human and animal health in an article appearing today, saying the officials are not doing enough to monitor cats, dogs and other carnivores for their possible role in transmitting avian influenza.

Writing in the journal Nature, the scientists also urge people living in areas where the A(H5N1) virus has infected poultry and other birds to keep their cats indoors.

The scientists are from the Erasmus Medical Center in Rotterdam, the Netherlands, and the Food and Agricultural Organization of the United Nations. They directed much of their criticism at the World Health Organization and the World Organization for Animal Health for emphasizing the lack of evidence that domestic cats play a role in transmitting the virus and contending that more research is needed.

Cats, tigers and leopards are known to have been infected with the virus in Asia and Europe. An author of the article, Dr. Albert Osterhaus, a virologist and veterinarian at Erasmus Medical Center, has performed experiments showing that cats can give the virus to other cats. But whether they do so in real life, and if so how often, is unknown.

Dick Thompson, a spokesman for the W.H.O., said yesterday by telephone that it agreed that more work was needed to determine the role of cats and other carnivores in the epidemiology of avian influenza.

Epidemiologists have found no change in the way the virus is spreading or causing illness, Mr. Thompson said. But he added, "Obviously, there still are major gaps in our knowledge and risk assessment."

He cited a resolution to be put before representatives of the health organization's member states at its annual meeting in May saying that "given the close association between domestic cats and people, vigilance for signs that cats are becoming more widely infected is essential."

In a telephone interview, Dr. Osterhaus said his team was issuing a precaution and not trying to sound too loud an alarm.

The team has found that cats can be infected through the respiratory tract. Cats can also be infected when they ingest the virus, which is a novel route for influenza transmission in mammals. But cats excrete only one-thousandth the amount of virus that chickens do, or less, he said.

The concern is that if large numbers of felines and other carnivores become infected, the virus might mutate in a series of events that could lead to an epidemic among humans.

But among the many unknowns is how long cats can excrete the virus, the minimal amount of virus it takes to cause infection and whether cats can excrete the virus without developing signs of illness.

Dogs, foxes, seals and other carnivores may be vulnerable to A(H5N1) virus infection, Dr. Osterhaus said. Tests in Thailand have shown that the virus has infected dogs without causing apparent symptoms.