An infection caused by the parasite Toxoplasma gondii. Toxoplasmosis is most commonly transmitted by contact with infected cat feces, eating contaminated meat, or drinking contaminated water. Toxoplasmosis can also be transmitted from an infected mother to her child during pregnancy. Symptoms, if any, include swollen lymph nodes and muscles aches that last for a month or more. In fetuses and people with weakened immune systems, toxoplasmosis can cause severe damage to the brain (Toxoplasma gondii encephalitis), eyes, and other organs. In people with HIV, toxoplasmosis of the brain is an AIDS-defining condition.