Cat-Borne Diseases

Letting your cat outside increases his exposure to contagious pathogens.

Letting your cat outside increases his exposure to contagious pathogens.

Your kitty may display perfect hygiene, but his clean coat isn't necessarily free of germs. Even house cats can harbor pathogens that can also infect humans. Some of these diseases don't produce symptoms in their feline hosts, so watch for warning signs in yourself and family members.


Cat scratch disease (CSD) is caused by a bacteria found in flea dirt—a polite term for the excrement of these pests. The pathogen gradually accumulates beneath your kitty's claws and in his mouth as he scratches at flea bites. While some humans infected with CSD had no prior contact with cats, about 90 percent of patients report proximity to felines before infection, according to Oregon Veterinary Medical Association. Your kitty can also spread resistant strains of the Staphylococcus aureus bacteria, which can cause a severe skin or respiratory infection.


Viruses tend to specialize in certain species, so there aren't many viral illnesses that your pet can give you. Rabies is a well-known exception: it is a deadly disease shared by people, pets and wild animals. Vaccinations against rabies are mandatory for cats and dogs throughout the United States. Uncharacteristic aggression and other sudden behavior changes are common in rabies victims, but you can't always tell from looking if an animal is rabid. The disease is almost always fatal as soon as symptoms appear, so always take bites from unfamiliar animals seriously. Contact a doctor immediately if you are bitten by an unvaccinated animal.


Parasitic fungus isn't pleasant to think about. Luckily, ringworm is the only common one that can infect both you and your kitty. Infestations of the tinea fungus can appear anywhere on your body after contact with the organism's spores. It spreads readily on inorganic surfaces, particularly clothes, sheets and blankets. Infections are usually treated with a topical ointment or oral antifungal medication prescribed by your doctor. You can look for signs of ringworm on your pet by grooming him several times a week to look for skin problems. Ringworm makes your kitty's hair fall out in small areas and irritates the skin, prompting him to scratch and spread the fungus to the rest of his body.


Protozoa aren't as famous as viruses or bacteria, but that doesn't mean they are harmless. Your cat can transmit toxoplasmosis through his waste after ingesting raw meat infested with the Toxoplasma gondii protozoan. Toxoplasmosis is a risk to individuals with weak immune systems, including pregnant women, but is not usually serious in heatlhy adults. (In fact, there's a good chance you've been infected already, like about a third of adults worldwide.) Cleaning your kitty's litter every day is a good way to prevent infection, because the organism needs at least a day before it becomes contagious, according to Weston Veterinary Clinic. It can travel through the air, so wear a mask when dumping litter and wash your hands afterwards. If you're pregnant or have an otherwise compromised immune system, don't handle cat litter at all.

About the Author

Quentin Coleman has written for various publications, including All Pet News and Safe to Work Australia. He spent more tan 10 years nursing kittens, treating sick animals and domesticating semi-feral cats for a local animal shelter. He graduated from the University of Delaware with a bachelor's degree in journalism.

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