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 a mother to her child during pregnancy. Symptoms, if any, include swollen lymph nodes and muscle aches that last for a month or longer. 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.