Toxoplasma gondii is an obligate intracellular, parasitic protozoan that causes the disease toxoplasmosis. It is found worldwide and is capable of infecting virtually all warm-blooded animals, but felids such as domestic cats are the only known definitive hosts in which the parasite can undergo sexual reproduction. Cleaning cat litter boxes is a potential route of infection.
Transmission is by ingesting cysts in undercooked meat. If transmission occurs in a pregnant woman, the fetus can acquire congenital toxoplasmosis, whose features consist of the triad of chorioretinitis, hydrocephalus, and intracranial calcifications. Most healthy people recover from toxoplasmosis without treatment. However, ill individuals can be treated with druglike pyrimethamine, sulfadiazine, and folinic acid.