I posted a thread about this exact question after I heard. If the egg came in contact with the flock, because Mareks spreads through dander, it’s the exposure on the shell of the egg that is a concern. None of the chicks actually hatched from the eggs, but me, not knowing my flock was at risk, didn’t practice perfect bio security after touching the eggs. So I could have gotten dander on my hands from handling them, then spread it to my flock.

It would be my fault for not practicing bio security and trusting that this member was a responsible breeder, but it’s still so infuriating.