Toxoplasmosis:

Toxoplasmosis (tok-so-plaz-MOE-sis) is a disease that results from infection with the Toxoplasma gondii parasite, one of the world's most common parasites. Toxoplasmosis may cause flu-like symptoms in some people, but most people affected never develop signs and symptoms. For infants born to infected mothers and for people with weakened immune systems, toxoplasmosis can cause extremely serious complications. If you're generally healthy, you probably won't need any treatment for toxoplasmosis. If you are pregnant or have lowered immunity, certain medications can help reduce the infection's severity. The best approach, though, is prevention.