Exposure is thought to provide at least partial life-long protection.
Infection is usually acquired by ingestion of undercooked meat and is usually asymptomatic, although it can cause a mononucleosis type of syndrome. It can cause devastating effects to a fetus, however, and can be transmitted transplacentally. It can also be acquired from cat feces, perhaps by aerosolization. Thus pregnant women who are not immune are advised not to change kitty litter boxes. In AIDS patients, or otherwise immunocompromised individuals, recrudescent toxoplasmosis is a common cause of encephalitis.