Stray and feral cats can carry more than a dozen infections that spread to humans, ranging from common skin conditions like ringworm to serious threats like rabies and plague. Feral cats carry the highest diversity of disease-causing organisms of any cat population, and even pet cats allowed outdoors are three to five times more likely to harbor these pathogens than indoor-only cats. Here’s what you’re actually at risk of catching and how each one spreads.
Cat Scratch Disease
Cat scratch disease is one of the most common infections people pick up from stray cats. It’s caused by bacteria that live in a cat’s bloodstream and spread between cats through fleas. Feral cats in warm, humid regions where fleas thrive have especially high infection rates, with some surveys finding the bacteria in over 80% of cats tested.
You don’t catch it from the scratch itself, exactly. Flea droppings collect under a cat’s claws and in its fur. When a cat scratches or bites you, those contaminated flea feces get pushed into the wound. The bacteria can also enter through a cat’s saliva contacting broken skin. Within a few days to a couple of weeks, the scratch site develops a raised bump, followed by swollen, tender lymph nodes near the wound. Most healthy people recover without treatment, but the swelling can persist for weeks or even months.
Toxoplasmosis
Cats are the only animals that shed the infectious form of the parasite that causes toxoplasmosis. An infected cat passes microscopic eggs in its feces for one to three weeks, but during that window it sheds enormous numbers of them. The eggs can survive in soil and sandboxes for months, which is how most people are exposed: gardening in contaminated soil, cleaning a litter box, or a child playing in sand where a stray cat has defecated.
For most healthy adults, the infection causes mild flu-like symptoms or no symptoms at all. The serious concern is for pregnant women and people with weakened immune systems. A first-time infection during pregnancy can cross to the developing baby, with the severity depending on which trimester the mother is infected. In people with compromised immunity, such as those with HIV or on immunosuppressive medications, the parasite can cause brain lesions, eye disease, or lung infections. In AIDS patients, toxoplasmic encephalitis is the most common cause of brain masses.
Ringworm
Despite the name, ringworm is a fungal infection, not a worm. Cats are the main reservoir for the fungal species responsible for most human cases, and some stray cat populations show infection rates approaching 100%. You can catch it through direct contact with an infected cat or by touching contaminated surfaces like bedding, furniture, or even soil where a cat has rested.
On human skin, it typically appears as a circular red patch with raised, scaly edges and a clearing center. On the scalp, it causes patches of hair loss with broken-off hairs and flaky skin. Stray cats themselves may show circular bald spots with scaly borders, but some carry the fungus without any visible signs, making it easy to pick up unknowingly.
Hookworm and Roundworm
Stray cats commonly carry intestinal parasites, and their feces contaminate the ground wherever they roam. Hookworm and roundworm larvae develop in soil or sand after eggs are passed in cat feces, then wait for a host.
Hookworm larvae burrow directly into bare skin, usually the feet. You can pick them up by walking barefoot or sitting on contaminated ground. Once under the skin, the larvae create intensely itchy, raised red tracks as they tunnel through tissue, a condition called cutaneous larva migrans. In rare cases, hookworm larvae can penetrate deeper into the intestines, lungs, or eyes.
Roundworm works differently. You typically ingest the eggs accidentally, through contaminated soil on unwashed hands or produce. The larvae can then migrate through organs including the liver, lungs, and eyes, causing inflammation wherever they travel. Children playing in yards or sandboxes frequented by stray cats are at highest risk.
Rabies
Rabies is rare in the United States, but stray cats represent a real transmission risk because they’re unvaccinated and encounter wildlife that carries the virus. A bite from a rabid cat is a medical emergency. Once symptoms appear in a person, rabies is almost universally fatal.
If you’re bitten by a stray cat, immediate wound care matters. Washing the bite thoroughly with soap and water reduces viral load at the wound site. A person who has never been vaccinated against rabies will receive both an immune globulin injection (given once, directly into and around the wound) and a series of four vaccine doses spread over two weeks, on days zero, three, seven, and fourteen. People with immune disorders receive a fifth dose on day 28. Treatment is highly effective when started promptly, even after a confirmed exposure.
Bite Wound Infections
Even without rabies, a cat bite is one of the riskiest animal wounds you can get. Cat teeth are narrow and sharp, creating deep puncture wounds that seal over quickly, trapping bacteria beneath the skin. Cat saliva contains bacteria that cause fast-moving infections. Redness, swelling, and pain can develop within hours of a bite, and untreated infections can spread to joints, tendons, or the bloodstream. Cat bites on the hand are particularly dangerous because of the concentration of tendons and joints close to the skin surface. Any cat bite that breaks the skin warrants prompt medical attention.
Other Bacterial Infections
Stray cats can carry several other bacteria that spread to people. Salmonella and campylobacter pass through cat feces and cause gastrointestinal illness with diarrhea, fever, and cramping. Cats can also carry MRSA, a drug-resistant staph bacterium, on their skin or in their nasal passages, potentially passing it through close contact or open wounds.
Stray cats can also harbor giardia and cryptosporidium, both waterborne parasites that cause prolonged diarrheal illness. These organisms spread through the fecal-oral route, meaning contact with contaminated feces followed by inadequate hand washing.
Plague and Other Rare Diseases
Plague still occurs in parts of the western United States, and cats are one of the primary domestic animals involved in transmitting it to people. Cats become infected by hunting rodents that carry plague-infected fleas, and they can pass it to humans through bites, scratches, respiratory droplets, or flea transfer. In January 2024, a case of human plague in Oregon was traced to an infected pet cat. The disease is treatable with antibiotics when caught early but can be fatal if diagnosis is delayed.
Tularemia is another rare bacterial disease cats can transmit through bites or scratches, and sporotrichosis, a fungal infection, can spread from infected cats through skin wounds. These are uncommon but worth knowing about if you regularly interact with stray cats.
Protecting Yourself Around Stray Cats
If you feed, trap, or care for stray cats, a few practical steps significantly reduce your risk. Wear thick gloves that resist bites and scratches whenever you handle a cat directly. Long sleeves and closed-toe shoes add a barrier against scratches and contaminated soil. Wash your hands thoroughly with soap and running water after any contact with a stray cat, its bedding, food bowls, or litter. Alcohol-based hand sanitizer works as a temporary measure but doesn’t replace soap and water.
Avoid touching your face, eating, or drinking while handling cats or cleaning areas where they’ve been. Wear shoes in areas where stray cats defecate, especially sandy or loose soil. If you’re gardening in an area frequented by strays, gloves and hand washing afterward go a long way toward preventing hookworm, roundworm, and toxoplasmosis exposure. Pregnant women should avoid handling stray cats and cleaning any area potentially contaminated with cat feces.
Any bite or deep scratch from a stray cat should be washed immediately with soap and water and evaluated by a healthcare provider the same day, both for infection risk and to determine whether rabies prevention treatment is needed.