Cats are the main domestic animal linked to human exposure to rabies.


Efforts to care for abandoned cats could mean more humans will be exposed to rabies, researchers at the federal Centers for Disease Control and Prevention say.


Those two trends could be on a collision course, says Charles Rupprecht, director of research for the Global Alliance for Rabies Control, who was senior author of the CDC study.

Dogs were the primary domestic carrier of rabies until the 1970s, when roundups of strays and vaccination programs eradicated canine rabies. That hasn't happened with cats.

"We didn't think it was OK to have (stray) dogs, but we think it's OK to create artificial cat colonies where they're exposed to wildlife that can transmit rabies," Rupprecht says.


Human deaths from rabies are rare in the United States — two or three a year — and there have been no deaths linked to cats in decades.

The issue is part of a debate over how to deal with unwanted cats and their offspring. There are 74 million owned cats in the United States, according to the American Veterinary Medical Association. Estimates on the number of feral cats vary from 60 million to 150 million.

Many cat groups want an end to euthanasia in shelters. Because most feral cats haven't been socialized to live with humans and aren't suitable for adoption, they see creating outdoor colonies where they're fed and cared for as a humane alternative.

Trapping, neutering, vaccinating and returning feral cats to the wild means they remain healthy and disease-free, and the colonies eventually die out, says Becky Robinson,co-founder of Alley Cat Allies n Bethesda, Md., which has people caring for colonies in all 50 states.

The researchers say vaccination programs are not thorough enough to end the threat. Cats have lower rabies vaccination rates than dogs; 38 states require vaccination for dogs vs. 30 for cats.

To be protected against rabies, cats need to be vaccinated once as kittens, then a year later and then at about three-year intervals, says Jane Brunt, a veterinarian and past president of the American Association of Feline Practitioners.

Capturing and recapturing feral cats two or three times during their lives to adequately vaccinate them is difficult, Rupprecht says. The study says achieving the level of coverage necessary to protect those who come into contact with the stray cats "is doubtful."

The Florida Department of Public Health has declared that feral cats raise public health concerns. The American Association of Wildlife Veterinarians supports bans on feral cat colonies because of the risks they pose to wildlife and human health.

The CDC paper disagrees with the notion that TNVR programs cause feral cat colonies to slowly decrease in size as cats die of natural causes. It cites studies showing that many continue to increase over time, either because not all animals are neutered or because of the arrival of new cats drawn to the food.

George Fenwick, president of the American Bird Conservancy in The Plains, Va., one of the authors of the study, says more feral cats will mean "the incidence of rabies exposure is going to increase at a fairly rapid rate."

His involvement in the study is causing fur to fly among supporters of the colonies. The American Bird Conservancy has promoted research showing that outdoor and feral cats are responsible for killing and eating many more birds and wildlife than previously known.

The CDC research on cats and rabies was published in the journal Zoonoses and Public Health. Zoonoses are diseases that can be transmitted from animals to humans.

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