Here's some info I copied/pasted...
"There are a few different types of Mareks in chickens. The most common are eye, visceral (tumor producing), and nerve.
The nerve version is known by some Fanciers as 'down in the leg', and symptoms range from slight to severe paralysis in the wings, legs, or neck, and usually results in death from trampling by other chickens, and/or the inability to get to food and water. There can be 'transient' paralysis that disappears after a few days, such as a dropped wing that suddenly corrects itself. In the eye version, you'll detect an irregularly shaped pupil, cloudy eye ('gray eye'), or sensitivity to light. It can result in blindness. The visceral version should be considered when a bird is just generally 'wasting'.
Mareks is extremely contagious but does not spread vertically (to the egg). Youngsters should develop a natural immunity (called 'age resistance'), by the time they're five months old. This is one of the reasons it is important to raise your youngsters separately from your oldsters. New birds coming in from other flocks are always potential carriers."
I have always heard & read that if you have chickens, you have Marek's. The wild birds are carriers. If your chickens have ever had a bird crap in their yard, they've been exposed already. But then I read this and it is definitely plausable!! It also makes sense as to where the disease comes from in the 1st place!! We have neighbors with chickens - granted, for the most part they're miles away, but feathers go very far in the wind!
"by Danverchick on Sat Dec 10, 2005 10:42 am
Mareks is a herpes virus carried in the feather follicles of essentially all chickens (and probably several birds). Birds usually develope innate immunity to it with age, and immunity is generally largely dependent upon genetics. I only have trouble with Mareks when I move my three month old birds from the growing pen to the pen right next to my older birds. I never have trouble with it in my older birds, or even with young birds if I wait until they start egg production before I move them next to the older birds. The three month olds I expose on purpose, I will usually lose 2-3 youngsters to it a year (out of 200 chicks). I expose them in order to see which birds are resistant, as I breed for genetic resistance to disease. The susceptible ones usually recover about half of the time(in my flock) and if they recover do not carry any more of the virus than any other exposed chicken...so I give them away as pets if I can find someone willing to take a survivor. My neighbors down the road take most of them and just let them range - neither the survivors nor any other birds show any permanent effects of the disease, and although she commonly has chicks running around (with momma hens), no one else there really gets sick. The capability for genetic immunity to Mereks is extremely high. The seasonality of the disease corresponds to molting (migration season) and probably have nothing to do with the wild birds at all (in order to contract it from wild birds, the wild birds must carry the exact same chicken version of the disease - but most are species specific and wild birds have independent species so that is not very likely). So - the source is usually your own chickens, or some nearby chickens molting somewhere...it is everywhere and so you can pretty much expect that most other chickens are exposed at one point. Since it lives in the feather follicles of your birds, when they start to drop their feathers, then they breath heavier concentrations of this herpes virus."
I think it's honestly some where in the middle as to the where it comes from. However, I really like her 'method' of controlling the disease! If our chickens are going to be exposed to it regardless of what we do or don't do...why not breed for resistance? That's why I initially tried to save the 'suspected' Marek's chicks. I was hoping for some immunity. The nerve form is difficult to watch though - the birds literally look drunk (or like me - lol). At some point they can no longer walk and must be handfed. I was unsuccessful at saving mine. Partly because I simply couldn't watch it any longer... I had Chuck cull them so they wouldn't suffer any longer. I am going to continue to do things exactly as I have been with one exception. I will not put chicks which are not vaccinated in with any of the existing chickens until they are laying. Natural immunity does occur. And even if you have them vaccinated, they can still get it from a farm 5 miles down the road because the vaccination you received may not be the 'correct' strain for the neighbor chicken's strain. Ack! At least I know now how my chickens got it. They were all day old chicks from the hatchery (and a few from the store where they supposedly had the vaccine - I paid 'extra' for those chicks!!) and all standard's received the Marek's vaccine. Well duh! Between the wild birds & the other chicken keepers for a 25-mile radius, my birds had to be exposed to it just by living.
Moral of the story: If you have chickens, you have Marek's. Even if you have never had any obvious signs or illness. Slim Shady & my spring chick order already placed will be the end of my bringing in outside birds. I hope to get an incubator for Christmas (oh please Santa!!), but I will only hatch my girls' eggs. I'm breeding for resistance...healthy & happy birdies. When I have my dream coop built, I'll decide then whether I want to start up with a new breed of chicken/duck/guinea/etc. Until then, I'm closed. :)
Cami
CHICKENS-101@yahoogroups.com
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