Cats often become infected when they eat an infected rodent or bird. The parasite reproduces in the cat's intestine, and a form of the parasite ends up in the cat's litter box, sand or soil. This form of the parasite becomes infectious within as little as one day, and is resistant to most disinfectants. Under certain temperature and humidity conditions, the parasite may live in soil for more than a year. Infected cats usually appear healthy.
Toxoplasmosis is one of the most common infections in the world.
Most cases go undiagnosed. Symptoms, if any, tend to resemble flu. Active infection normally occurs only once in a lifetime. Although the parasite remains in the body indefinitely, it generally is harmless and inactive unless the immune system is not functioning properly. If a woman develops immunity to the infection at least six to nine months before pregnancy, there rarely is any danger of passing it on to her baby.