Does anyone know anything about FEAR FACTOR the TV show on SKY TV?

Hosted by Joe Rogan the contestants face their biggest fears, one of the 3 stunts is usually something gross to eat or put in their mouths or lie in etc etc! I've seen them throw dead rats into a bucket using only their mouths, eat horse rectum, eat live roaches/worms/other general disgusting animal parts. Ive seen them eating partly formed embryo parts from chicken or duck eggs, really old and rotten eggs or fish guts etc. I want to know how'd they know they're not gonna catch some gross disease or infection from these things?!! Do they disinfect all the dead rats or live cochroaches before they do the stunts? Is it just a risk they take but surely there would be some sort of comeback from someone being infected by something!? Its a bit random but I have always wondered this!