Ok, I read this article on it. Sounds like something you'd want to get rid of and once the bird is infected it will infect others?
the article states its transmitted to the eggs, but then it also talks about treating with antibiotics to prevent reduction in egg production.
If it were me I think I'd cull the bird that has it, clean up real good, make sure my other chickens didn't have it.
After reading this, i don't think I would eat the egg knowingly, but since it seems to be present in many comercial egg laying centers, i probably have at some point ... before I got my own chickens.