Toxoplasmosis is a disease caused by the protozoan Toxoplasma gondii, which lives in muscle and brain cells of a host animal. It is transmitted by eating uncooked, infected tissue. In cats, the parasite can live in intestinal cells, and people risk infection by contact with the cat's feces. Toxoplasmosis damages the brain, eyes, muscle, heart, liver, or lungs. If acquired during pregnancy, the parasite can severely damage a fetus. The disease may respond to sulfonamides used with pyrimethamine. Some European countries conduct routine prenatal and newborn screening for toxoplasmosis. Infected women are treated with an antibiotic to reduce the risk of transmitting the parasite to the fetus. The United States does not require such testing.