LOS ANGELES (MCT) — A wily parasite well known for influencing the behavior of its animal hosts appears to play a troubling role in humans, increasing the risk of suicide among women who are infected, new research shows.

Chances are you or someone you know has been infiltrated by the parasite, called Toxoplasma gondii. Researchers estimate that T. gondii is carried by 10 percent to 20 percent of Americans, who can get it by changing litter used by infected cats or eating undercooked meat from an animal carrying the bug.