Quote:
You either have blackhead in an area or not. It is very common in the Southern USA. Our wild turkeys (who have ALL the space, water, great life) are inflicted with black head at a consistent % die-off annually. Ours is a humid, very hot environment which invites and nurtures pathogens (see the jungles of Africa). It also doesn't ever get cold enough, long enough to kill things here.So, it also has to do with WHERE you live, what strain of Marek's you have on premises (if any), etc.. etc. -- all the good diet, space, exercise, hydration, straight bleach, in the world won't overcome a virulent strain of Marek's as it is incurable. You can vaccinate as chicks and hope it takes, keep turkeys on premises (hope it takes) or slowly build your flock's resistance to your particular Marek's strain(s). I have heard of folks in Arizona, New Mexico or other more arid sections of the country who swear and tell me over and over, they never have external parasites, never have any disease. I have also heard of someone not having Marek's for decades and then ONE bird brings a new strain on the place and it strikes at random and suddenly, they have Marek's. Different places, different breeds of chickens. I agree all those things you mention are important, factors, etc. but that is not the whole story.
I must be honest, here in the South, I wouldn't believe anything anyone said if they claimed never to have had death as a result of sickness or never to have had mites or some such parasites (if they had kept chickens long enough). I certainly would not want any of their birds.