Some scientists claim Toxoplasma gondii (Toxo for short), a tiny parasite found in cats and spread in their feces, can alter its host's behavior in its own evolutionary interests. Most people know about Toxo because of its link to toxoplasmosis, an infection that can damage the fetus in pregnant women. "Newborns affected with Toxo tend to have a lot of problems," says Temple psychologist Lauren M. Ellman, "including low birth weight, enlarged liver and spleen, anemia, convulsions, fluid in the … brain."