Hello all. I recently lost a chicken that was about 9 months old in a sudden death. Externally she appeared very healthy, and I had not noticed any sickness or symptoms. I sent her to a lab for a necropsy and it is "presumed" to be Marek's Disease. They stated she was in good nutritional condition and I had not noticed any weight loss. Apparently, they found lesions inside her consistent with the disease. Since Marek's is so common and is highly contagious, it seems safe to assume the rest of my flock is also infected. None of them have been showing any signs of sickness so far. They are four hens, and are all around the same age, 9 - 10 months old. I don't know if they were vaccinated as chicks for Marek's. My question now is what I could do to help the rest of my flock survive this exposure to the disease. I get the impression that much of survival is based on an individual chicken's genetics. Their lives are pretty stress-free, so maybe there isn't much I can do, but I want to improve their chances if it's possible. Is it too late for vaccination? Should I get a blood test from one of them to be certain it is Marek's? Thank you all for any information or suggestions.