t gondii


“Crazy cat lady” is just a stereotype, but hanging out with so many cats could actually have some psychological risks if just one of them is harboring the parasite Toxoplasma gondii.

It’s an International Cat Day and Microbiome Monday mashup!

Microbes affect not just your body, but your innermost thoughts and feelings. Early research suggests that appetite, mood, mental illness—even bizarrely specific behaviors like the way we dress—can all be manipulated by microbes.

A parasite called Toxoplasma gondii lives inside many animals, including some mice. But it can only reproduce inside cats. So how does it get from mice to cats? Incredibly, several studies show that this tiny, single-celled protozoan alters the mouse’s brain and controls its behavior.

1) Mouse swallows T. gondii

2) Parasite enters brain, making mouse lose its fear of cats

3) Fearless mouse is easily eaten

4) Parasite reproduces in cat intestines and exits with feces

Roughly a third of all humans are infected with Toxoplasma gondii, the parasite that turns mice into zombies—and it appears to influence our behavior as well. Some studies show infected men break more rules and dress more sloppily, while infected women become more sociable and dress better. Both men and women have slower reaction times and get in more car accidents.

Learn more about your microbiome in The Secret World Inside You, closing August 14.