Ask Dr. Richards: 01/02

Question:  A cat infected with feline immunodeficiency virus (FIV) bit me recently. Can FIV infect people, or should I limit my worrying to all of the other nasty bugs in a cats mouth?

Answer:  There are many microorganisms in a cats mouth capable of causing significant bite wound infections. In fact, virtually every cat bite wound I ever received – and there have been many – became infected. But thankfully, feline immunodeficiency virus (FIV) has demonstrated no evidence of being infectious to humans. No  studies of which  Im aware have raised suspicion. One of the most recent studies examined blood collected at a veterinary conference from more than 200 veterinarians, laboratory workers, and others occupationally exposed to FIV.

Study participants (of which I was one) reported working with cats for an average of 17 years, with multiple exposures (from cat bites, scratches, and inadvertent needle-sticks) per year. Utilizing very sensitive and sophisticated tests, the investigators found no evidence of infection in this high-risk group.

Nonetheless, I believe caution is in order. Even though there is no evidence that FIV poses a risk, I suggest minimizing exposure of an FIV-infected cat to the very young, the very old, and those with a compromised immune system, simply because these individuals do not have the same ability to fight infection as do others. If ever FIV were to cause a problem, it would most likely do so in those groups.


Question:  A cat that was bitten by an unknown animal bit me and then ran away. I understand that he had received a rabies vaccine five or six years ago, but hasnt been given a booster shot since then. Ive been concerned about getting rabies from the bite of this cat. Ive heard that feline rabies shots last a long time, so maybe this cat was immune when it was bitten and therefore it couldnt have infected me. Am I correct?

Answer:  I wouldnt count on it. But let me explain further. Under ideal circumstances, if a cat bites someone, the offending kitty should be strictly confined for 10 days and closely observed for signs of rabies. (This recommendation stands whether or not the cat is current on its rabies vaccine because not all vaccinated cats are given protection.) If no signs of rabies develop during that period of time, then the bitten person is off the hook; the cat could not possibly have transmitted the disease. Why? Because rabies is transmitted when the virus is introduced into a bite wound or onto mucous membranes or open cuts in the skin. In order for virus to be transmitted, it must be present in the cats saliva – a situation that doesnt occur until a cat is within ten days of showing signs of the disease.

But in your case the biting kitty is nowhere to be found. To make matters worse, the cat has to be considered potentially exposed to rabies because it was bit by an animal of unknown infection status. I recommend that you contact your local health department right away. The possibility that the cat was rabid is quite remote, but cat bites are to be taken very seriously, and it is possible that the health department will recommend you receive post-exposure rabies inoculations. (I informed the inquirer of this immediately upon receiving her letter.)

Unvaccinated cats
Rabies vaccines might induce protection in cats that lasts for many years. But to my knowledge, studies extending beyond three years have not been performed for any of the currently available vaccines. Because of the justifiable concern that humans may be exposed to rabid pets, some locales legally mandate rabies vaccination of cats. Whats the consequence of not vaccinating your cat?

Unvaccinated dogs, cats, and ferrets exposed to a rabid animal should be euthanized immediately. If the owner is unwilling to have this done, the animal should be placed in strict isolation for six months and vaccinated one month before being released. (From Compendium of Animal Rabies Prevention and Control, 2001)

While you may think your cat will never be exposed to a rabid animal, you cant be sure. For example, what if you came home to find your indoor-only cat playing with a bat that somehow got into the house – and then escaped. That would be considered a potential rabies exposure by your health department, and if you are unable to document that your cat is vaccinated, he or she may face a six-month quarantine or worse.