The single-celled Toxoplasma gondii has earned plenty of notoriety for its life cycle that involves mice. T. gondii finds a rodent through soil that’s been contaminated with larvae-infested cat poop. Once has invaded its host’s brain, it begins subtly steering its behavior. Whereas mice are normally fearful of cat urine, T. gondii-infected mice pay it no mind and become much less shy about exploring open spaces. If things go according to the plan, the no-longer-bashful mouse is soon gobbled up by a cat, and the process begins anew. The jury is still out as to whether T. gondii can have any mental effects on the humans it infects.
