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. Severe toxoplasmosis can cause damage to the brain, eyes, or other organs. In people with HIV, toxoplasmosis of the brain is an AIDS-defining condition.