- The brain parasite Toxoplasma gondii causes rodents to not fear cats, which will then consume the rodent, allowing the parasite to reproduce in the cat gut. A new study shows that the parasite strips away rodents' fear of all predators, not just cats, and acts less specifically than once thought. https://www.cell.com/cell-reports/fulltext/s2211-1247(19)31669-9 52 comments science