Brain Parasite Strips Rodents of Fears of Felines—and So Much More
by Katherine J. Wu/Smithsonianmag.com
Rodents really have it rough. When hit with a Toxoplasma gondii infection, mice don’t just end up with parasites in their brains. They also get weirdly reckless, venturing into scary new environments and brashly investigating the smells of animals they should fear, like cats, foxes and intrusive human researchers, according to a study published this week in Cell Reports.
The feline part of this story has long been known, and often spun into a narrative that’s perhaps made the parasites seem more devious than they really are, reports Kelly Servick for Science magazine. While Toxoplasma spends much of its time hanging out in a wide variety of warm-blooded animals, including rodents and humans, it can only complete the sexually reproductive stage of its life in wild or domestic cats. So when researchers saw infected rats developing a kind of fatal feline attraction, they theorized that Toxoplasma had found a way to hijack the rodent brain and strip it of the singular fear that made them harder to catch and eat—and ingeniously ensuring the parasites’ continued success.