I may have made a connection . I had a hen who was 3 years old. 2 months ago, I found her laying on the ground with what I thought was a broken leg. I splinted her leg and put her in a sling in a cage. She was on my patio but it got too hot. I moved her into the chick pen
so the chicks could keep her company. She was not eating, after 2 weeks I euthanized her. A week later, a chick "broke" her leg. I splinted it. 2 days later another chick had a "broken leg. Those chicks did not have broken legs, and might be that the hen didn't either.
So if wasting away and dying (while acting perfectly normal) can be a symptom of one type of Marek's, then I can say that I've 4 paralyzed/staggering and have a gasp, and 5 that wasted away and die, and 1 had paralysis, staggering, falling over, and the gasp, but recovered, Then I've had 9 die in 2 years of Marek's. Can Marek's attack one chicken at a time, 10 in 2 years?

So if wasting away and dying (while acting perfectly normal) can be a symptom of one type of Marek's, then I can say that I've 4 paralyzed/staggering and have a gasp, and 5 that wasted away and die, and 1 had paralysis, staggering, falling over, and the gasp, but recovered, Then I've had 9 die in 2 years of Marek's. Can Marek's attack one chicken at a time, 10 in 2 years?