A parasite infection. Most people are not aware that they have been infected because they have either mild or no symptoms. People with impaired immune systems, such as AIDS or cancer, can develop more serious infections including: central nervous system (CNS) disease, eye involvement or lung infection. The parasite can be acquired by handling cat feces, or by eating undercooked infected meat (especially lamb, pork, or deer). Women who are pregnant or want to become pregnant should avoid cat feces and undercooked meat. An infection can lead to spontaneous abortion or fetal abnormalities.