When humans began transporting domestic animals around the globe, a microscopic organism seized the opportunity to start its own wildly successful journey: hitchhiking inside their brains.

Today, more than 40 million people in the United States and up to a third of the global population are estimated to be infected with Toxoplasma gondii, a single-celled parasite with a singular goal: to infect any warm-blooded animal until it is ingested by a wild or domestic cat. Within these feline species, the parasite can sexually reproduce to create millions more versions of itself.

“T. gondii has been called the world’s most generalist parasite and is an astonishingly interesting and understudied organism,” said Eben Gering, assistant professor at NOVA Southeastern University in South Florida, and former Michigan State University postdoc in the lab of integrative biology professor Tom Getty. “After infecting a feline host, T. gondii shifts from asexual to sexual reproduction to produce millions of diploid spores that are shed via feces and remain infectious in soil or water for months. It’s an evolutionary jackpot from the parasite’s perspective.”

Gering and Zachary Laubach, a postdoc at the University of Colorado-Boulder and former member of University Distinguished Professor Kay Holekamp’s lab, conducted a first-of-its-kind study into the role of T. gondii in the wild, establishing its definitive presence and influence among free-living hyenas.   

Read more about the study on the College of Natural Science website.