Mg only passes when it is shed. Most of the time a bird stressed or sick enough to shed virus is not laying. The chance of getting stuff in an egg is very very rare IMO, I don't worry about it. But a bird having something that gets activated by shipping or driving is not that uncommon. I mostly worry with adult birds. babies have not had as much time to get something and then not show symptoms.
Did I read this wrong and are we talking about eggs?
I agree however, my biggest worry is shoes, I have yard shoes that stay in the yard and dont go anywhere else. Mind you, I forget and go barefoot mostly, so I'm a bad girl.