Touching hands

Why is it that everyone automatically touches my baby's hands!??! By the time they touch them it's too late to say something. I dont want to be the jerk that straight away tells people not to touch her hands but by the time they've touched her they've already gotten their germs on her. I dont know what to do in this situation. A few times I've made it obvious I wasn't pleased and grabbed a wipe and cleaned her hands off.