Toxoplasmosis is an infection caused by Toxoplasma gondii, a parasite transmitted through contaminated food, water, or cat feces. It is usually mild but can be dangerous in pregnancy, potentially causing birth defects or miscarriage. Symptoms may include fatigue, muscle aches, and swollen lymph nodes. Prevention involves proper food hygiene and avoiding cat litter. Pregnant women with toxoplasmosis may need treatment to protect the baby.