Article on Bird Flu Criticizes Effort to Monitor Cats and Dogs
By LAWRENCE K. ALTMAN
Published: April 6, 2006
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.