Toxoplasmosis
T. gondii infections have the ability to change the behavior of rats and mice, making them drawn to, rather than fearful of, the scent of cats. This effect is advantageous to the parasite, which will be able to sexually reproduce if its host is eaten by a cat. The infection is widespread in the brain, with more cysts targeting the parts of the brain corresponding to fear. The widespread nature of the infection causes many previously unnoticed symptoms in the rats.
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