An infection with a parasite known as Toxoplasma gondii.

A common parasite found in undercooked meat and cat feces causes toxoplasmosis. Most people with the infection don't have symptoms. But it can cause serious disease for pregnant women, infants and people with weakened immune systems.

Some people with toxoplasmosis have flu-like symptoms. These can include a fever, headache, muscle aches and skin rash. Toxoplasmosis also can affect eyes, causing eye pain and poor vision.

Medicines can treat the infection. Treatment might involve taking more than one medicine. Not eating raw meat or handling cat litter can help prevent the infection.