Why do people hoard pets? Psychologists have explained the phenomenon as arising from early childhood experiences. Animals are often stable fixtures in an otherwise dysfunctional life. 

Yet what if your cat makes you even more dysfunctional? An evolutionary biologist named Jaroslav Flegr argues that many house cats carry organisms that invade our brains, leading to mental disorders like schizophrenia as well as causing suicides and car crashes. In fact, according to Flegr, cats may "kill as many people as malaria, or at least a million people a year.”

Flegr says the cause of all the harm is an intestinal parasite called Toxoplasma. There's a reason pregnant women are told to stay away from litter boxes. Toxoplasma is found in cat stools. 

Is Flegr on to something? Read this fascinating article at The Atlantic