Cats can transmit a handful of infections to humans, including parasitic, bacterial, fungal, and viral diseases. The most well-known is toxoplasmosis, but cats can also pass along cat-scratch disease, ringworm, intestinal parasites like hookworms, and in rare cases, rabies. For most healthy adults, the actual risk from any of these is low, especially with basic hygiene habits.
Toxoplasmosis
Toxoplasmosis is caused by a microscopic parasite that cats pick up by hunting and eating infected rodents, birds, or other small animals. Once infected, a cat sheds the parasite in its feces, where it can survive in soil or litter for long periods. You can become infected by accidentally ingesting the parasite after cleaning a litter box, gardening in contaminated soil, or eating unwashed produce from a garden where cats have been.
About 11 percent of the U.S. population aged six and older has been infected at some point, and in some parts of the world that figure exceeds 60 percent. Most people never realize they’ve had it. In healthy adults, the immune system keeps the parasite in check, and symptoms are either absent or feel like a mild flu. The real danger is to pregnant women and people with weakened immune systems. A new infection during pregnancy can pass to the unborn child and cause serious complications including vision problems and developmental issues.
It’s worth noting that undercooked meat, especially pork, lamb, and venison, is actually a more common source of toxoplasmosis than cat litter. Contaminated shellfish and unpasteurized goat’s milk can also carry it.
Cat-Scratch Disease
Cat-scratch disease is a bacterial infection spread through scratches, bites, or even a cat licking an open wound. It affects roughly 1 in every 10,000 people per year. Kittens are more likely to carry the bacteria than adult cats because they tend to scratch more and are more likely to be infected.
The hallmark sign is a swollen, tender lymph node near the scratch site, usually appearing a week or two after the injury. The scratch itself may develop a small bump or blister. Most cases resolve on their own within a few weeks, but in people with compromised immune systems the infection can spread to the liver, spleen, or eyes and become serious enough to require treatment.
Ringworm
Despite the name, ringworm isn’t a worm. It’s a fungal skin infection, and cats are one of the most common sources. Infected cats develop bald, scaly, crusted patches, often on the face, ear tips, tail, and feet. Some cats develop small itchy bumps across the skin, and severe cases can produce larger bumps with open sores. But some cats carry the fungus without showing any signs at all, which makes transmission sneaky.
You catch it through direct contact with an infected cat or by touching contaminated surfaces like bedding, furniture, or grooming tools. The fungal spores are hardy and can linger in the environment for months. In humans, ringworm typically shows up as a red, circular, itchy patch on the skin. It’s treatable with antifungal creams, though stubborn cases can take several weeks to clear.
Hookworms and Other Intestinal Parasites
Cats can harbor hookworms and roundworms, both of which can infect humans. Hookworm larvae live in contaminated soil or sand and penetrate exposed skin, typically bare feet. Once they burrow in, they migrate through the upper layers of skin and cause a condition called cutaneous larva migrans: intensely itchy, raised, winding red tracks that appear within about 10 to 15 days of exposure. The larvae eventually die on their own, but the itching can be severe enough to need treatment.
In rare cases, hookworm larvae penetrate deeper and migrate to the lungs or intestinal tract, causing inflammation. Roundworm larvae from cats can also migrate through the body and, on rare occasions, reach the eyes, a condition that can affect vision. Children are at highest risk because they’re more likely to play in soil or sandboxes where cats have defecated.
Rabies
In the United States, cats are the most frequently reported rabid domestic animal, with roughly 200 to 300 confirmed cases in cats each year. That said, over 90 percent of animal rabies cases still occur in wildlife like raccoons, foxes, bats, and skunks. Cats typically contract it from encounters with these wild animals.
Cat-to-human rabies transmission is extremely rare in the U.S., largely because of widespread vaccination. But unvaccinated cats, especially outdoor or feral cats, pose a real risk. The CDC estimates that post-exposure treatment related to potentially rabid cats costs approximately $33 million annually, which reflects how seriously any possible exposure is treated. Keeping your cat’s rabies vaccination current is the single most important step for preventing this one.
Who Faces the Greatest Risk
For healthy adults, the risk of catching a serious illness from a pet cat is genuinely low. The groups that need to be more careful include pregnant women, young children, elderly adults, organ transplant recipients, and people living with HIV/AIDS or other conditions that suppress the immune system.
Among all cat-related infections, toxoplasmosis draws the most concern from physicians treating immunocompromised patients. Cat-scratch disease and ringworm are the two infections most commonly acquired directly from cats rather than from other environmental sources. For people with weakened immunity, these otherwise minor infections can become systemic and far more difficult to treat.
Practical Prevention
Most cat-to-human infections are preventable with straightforward habits:
- Wash your hands with soap and running water after touching your cat, handling litter, cleaning food bowls, or coming into contact with pet waste. Hand sanitizer with at least 60 percent alcohol works as a backup when soap isn’t available.
- Scoop the litter box daily. The toxoplasmosis parasite typically needs one to five days after being shed to become infectious, so prompt cleaning reduces risk significantly.
- Keep cats indoors. Indoor cats are far less likely to encounter infected prey, rabid wildlife, or contaminated soil.
- Feed commercial cat food only. Raw or undercooked meat can infect your cat with toxoplasmosis and other parasites.
- Avoid rough play that leads to scratches or bites, especially with kittens.
- Stay current on veterinary care. Regular deworming, flea control, and rabies vaccination eliminate most of the transmission risk.
If you’re pregnant, the CDC recommends having someone else handle litter box duties when possible. If that’s not an option, wear disposable gloves and wash your hands thoroughly afterward. Avoid adopting or handling stray cats, especially kittens, during pregnancy. Keeping your existing cat indoors and feeding it commercial food are simple steps that dramatically lower the chance your cat picks up an infection in the first place.