As Bird Flu Spreads, Man's Best Friends Get a Second Look

March 12, 2006 — -- Pet lovers around the world reacted with dread when a cat in Germany was discovered dead last month, a victim of bird flu. Alarmingly, tests confirmed that the cat had died of the H5N1 strain of the virus, a form known to be deadly to humans.

As panic set in, various news reports stated that animal shelters in some European countries were overwhelmed with healthy animals dropped off or abandoned by their owners. Several countries have enacted quarantine zones where avian flu has been discovered, and German officials are enforcing a "cat curfew," requiring owners to keep cats indoors in affected areas.

Is it merely panic, or are there serious risks to pets and to families with cats and other pets? Is there anything pet owners can do to protect their pets and themselves from disease?

Risks Are Real, Experts Say

Dr. James R. Richards, director of the Cornell Feline Health Center at the Cornell University College of Veterinary Medicine in Ithaca, N.Y., believes quarantines and curfews are a sensible preventive step.

"I don't think it's an overreaction at all," Richards said. "It is a concern on a number of different levels. Cats may play a role in transmission of the virus to humans," though he is quick to point out that there is currently no evidence that cats are a risk to humans.

The virus, Richards noted, has shown up in cats before. The H5N1 virus was discovered in tigers and leopards in a Thailand zoo as early as 2003. Household cats in Thailand have also died of the H5N1 virus, according to the World Health Organization.

Research conducted since these feline deaths has confirmed that cats can harbor the H5N1 virus and, of greater concern, can transmit the killer virus to other cats through respiratory secretions, feces or urine.

Can Your Pet Infect You?

Many animals, including dogs, cats and other pets, can transmit viral or bacterial diseases to humans, either through direct contact with bodily secretions or through parasites like fleas. Examples of these zoonotic diseases include salmonellosis, bartonellosis (cat-scratch disease), tapeworm, roundworm, cryptosporidiosis, giardiasis, toxoplasmosis and rabies.

The greatest concern to health officials is the ability of viruses like H5N1 to mutate in the bodies of infected animals into forms that are easily transmitted to humans.

Some medical researchers theorize that the 1918 influenza virus, which killed between 20 million and 40 million people worldwide, originated as bird flu but then mutated in an infected pig into a form deadly to humans.

There is no current evidence that the H5N1 virus has undergone such a mutation. But as the virus infects mammals like cats, the likelihood increases that it could mutate into a form transmissible to and among humans. Medical experts consider that a worst-case scenario.

"Influenza is a very mutable virus," Richards said. "We're learning as time passes what the virus can do."

Practical Tips for Pet Owners

Understanding the symptoms of pet illnesses like influenza can help minimize the spread of disease, said Nicole Baumgarth, associate professor of immunology at the University of California at Davis School of Veterinary Medicine.

"Usually when cats feel ill, they withdraw and they hide out," Baumgarth said. She adds that in cats, avian flu can show up as a gastrointestinal illness. "It might not show up as a respiratory illness."

"They might show signs of diarrhea. They might look ill. They might have a fever and may be vomiting, and their fur might not be as shiny," Baumgarth said.

Richards also offers some practical tips for pet owners. "There are some common-sense ways of living with cats to reduce the transmission of disease," he said.

These include washing hands before eating and after handling cats or litter boxes, annual veterinary checkups, practicing flea and tick control, and covering children's sandboxes when not in use.

"I've actually been a proponent of keeping cats indoors for years," Richards said. Aside from protecting cats from diseases, the practice safeguards cats from accidents.

A measure of objective reality might be in order, Baumgarth said. "The fact is that the people who have been infected have been in intimate contact with birds," she said. "Get rid of the chickens in your backyard if you're really worried."