I have read where some people take the used litter out of turkey coops and use it in their chicken coops to build up immunity in their flocks, since turkeys seem immune to it.
It's not that turkey's are immune to mareks, it is that turkey mareks, which is used in the only vaccine we, as backyard chicken keepers, can get, is not a virus that chickens can get, thus making the turkey droppings, kinda like a vaccine and the hope is that the dropping will produce a vaccine like reaction in chickens.. The turkey version of mareks does make the turkeys sick and acts the same way as chicken mareks, cow mareks, ect, since this is a herpes virus, with I think 9 different strains?....yes, some breeders are experimenting with using the turkey droppings as a "vaccine" for their flocks, rather than buy the turkey vaccine. There are 3 vaccines for mareks, one of which is made from the turkey mareks virus.