I have held off writing this as I wasn't sure what we are going to do or how we will be handling our current situation. I still don't know, but I hope someone can share something that might help. Approximately two weeks ago, I noticed a pullet with bloody stool. I treated all of the birds in her little pen with Corid. I also examined the other pens and treated one other group. She was an AustralorpxHolland with 4 sisters. The other pen had a Holland cockerel (mhollow's) an OrpxHolland cockerel and 4 pullets. All of these birds were from my June hatch.
The day before, I had shared a cockerel and 3 pullets from my late July hatch with a girl whom I have been working with since last fall. These were her first chickens and we were both very excited.
Things quickly took a turn for the worse. I have lost 30 of the 36 birds I had after culling my extra cockerels. A brand new coop for my friend is now probably contaminated and she lost all of her birds. There were a handful of odd symptoms, but most of our findings pointed to Marek's Disease. I was around many chickens this summer, and many farms. I don't know where or how it came from. It only affected my young ones, although after calculating, I realized that I don't know if all of my grown birds had been vaccinated. This is so frustrating and heartbreaking and so.....WASTEFUL, that I don't know what to think. The remaining 2 AustralorpxHolland pullets & one pure Holland trio are all that I have left from an entire year's worth of work. MHollow's pair that he shared in August also never became sick.
The vaccination for Marek's costs $16 (that I saw) and does 1000 birds. I read that some people thought that was a waste of money for throwing 99% of it away afterwards. I'll tell you one thing, I would pay $16 in a heartbeat to have those birds now.

We have discussed having a closed flock and breeding for resilience because obviously somebody had it to pass it on to the trio. The grown Holland roo, father to all of them, wasn't affected, either.
I am sorry this is so long. I wanted to share the information I received in August, but to be honest, I am just wiped out. Devastated. I haven't had a bird go down in 48 hours - a miracle. If anyone has experience with this, I would appreciate anything you can tell me.
Thanks for listening.