There are certainly aspects of that which could indicate Marek's but she is a long way off needing to be euthanized I would say. You will need to watch out for the others suddenly setting upon her as that can happen, so placing her in a pen of her own next to them where she cannot be harassed if...
The thing with Marek's is that it has dormant phases like the cold sore virus in humans (both are Herpes viruses), so you cannot tell who is carrying the virus until they have an outbreak and what causes an outbreak in one person may not trigger it in another, so everyone doesn't have an...
My guess would be that all the birds in question in this thread were probably suffering from Marek's disease which is incredibly common and widespread.
@christinethemac How old is your bird?
The best that you can do is provide a good quality vitamin supplement and supportive care but once they...