The thing is this.. many animals can
carry strains of something that isn't effecting them that MIGHT effect another species..
An example is Coccidia.. there are 9-11 strains KNOWN to effect chickens.. But other strains that may effect dogs, goats, cows.. Any of those species could be carrying strains that effect another animal without it impacting them at all..
So a chicken can NOT catch Turkey herpes. And a turkey can NOT catch chicken herpes.. but can either carry the other and pass it around.. I personally feel hard pressed to think they CAN.. otherwise how does it hitch a ride on other wild birds?? There are wild turkey in lots of locations, and it's said to travel up to 2 miles on the air.
Have you already absorbed info from the following link? If not, maybe it can give more clear answers than I am able..
Marek's Virus FAQ
Also I would look at some of the necropsy threads and see if anyone on there can look at your photo.. maybe they will have seen those spots.. I haven;t taken time to look through Dr google yet for you.. maybe your state vet will give a look via email and give a free professional opinion??