What exactly did your necropsy report say? Can you get a copy of it, maybe?
The visceral tumors are a pretty straight giveaway, but it is important that the tumors alone can't show the difference between Marek's and Avian Lymphoid Leukosis. Usually only very experienced veterinary poultry examiners can tell the difference. Did a state lab do your necropsy, or a local vet?
Really, to be totally honest, Marek's does seem far more common than ALV, so the chances that it is Marek's is higher. But, I just wanted to mention ALV, just in case.
Anyhow, as to why your other birds didn't die-- it's possible they built up resistance. Where are they all from? Are they all from the same line, or are they hatchery birds, or?? There are SO many variables. Were any vaccinated?
A few things to consider:
1) Any chicken exposed to Marek's virus (it is inhaled, via dust/dander) will contract the virus, regardless of vaccination, and will shed it. According to a study I read, vaccinated birds shed the same amount of virus as unvaccinated birds. They will shed varying amounts of the virus until they die.
2) Marek's virus has been found to live outside of a host, in the environment ( coop, run, yard, etc) for a minimum of 1.5 years.
Given these two things, it would probably be irresponsible to give roosters away. If you do, just fully inform people that the roosters are probably carriers of Marek's virus and can infect any birds they come into contact with. That's the sad, unfortunate, and crummy truth.
I'm not sure what you mean by taking care of someone else's chickens. If you mean going to someone else's property and taking care of thier birds, you probably can, but I'd advise you to shower fist and get a set of shoes that you've never worn out to your chickens before. When I visit other people's flocks, I take a bottle of Odoban with me and spray my shoes well, as well, before getting out of the car. This might seem extreme but I am very dedicated to not needlessly spreading the disease if I can help it.
All this said, this disease can be confusing even for those of us that have been eyebrows-deep in research!! Please don't feel too discouraged. We are all supportive of each other here.
When I clean my coop, I use a shop vac with a drywall filter, and suck the dust out that way. I try to do it on a day that isn't too windy. I scoop and shovel out as much bedding as I can before I run the shop vac, so that the shop vac doesn't fill up immediately.
Another option is to clean out as much as you can without the leaf blower, then on a very dry day, wet the dust down and wipe it out manually. It's a drag to do it this way, trust me, but it's an option. Let the coop dry completely before putting fresh bedding in.
RIP, Squeaky.
