[Best of 2019] Billions are infected by a cat poop brain bug, but studying it is vexing researchers

What if I told you that there is a good chance you are carrying a parasite that is transmitted through cat poo? Two billion people around the world carry Toxoplasma gondii so there may be more than a 25 percent chance that it is in your body too. Toxoplasma is closely related to Plasmodium, the …