A parasitic infection transmitted to humans by cats affects billions of people and can alter their behavior. New research ...

It might still affect human behavior in important ways. The infection is caused by a brain parasite transmitted by cats. The parasite lives in a sort of symbiosis with our furry friends.

This is one of the most common parasites in the world and more than 40 million Americans are estimated to carry it. One way humans can come into contact with this parasite is through cat feces ...