Some excellent info about Mareks

Lots of good info in there, for sure.

A couple of main points:

Dander (with Marek’s viruses attached) comes in on the wind. They say "if your birds breathe, they've been exposed to Marek’s". I for one am convinced this is true. Practical implications of this are that culling a bird with Marek’s won't help, and keeping a closed flock won't help either.

Breeds and strains vary considerably w.r.t. genetic resistance to Marek’s. It is definitely possible to breed for Marek’s resistance (Coopslave, I think you said that you developed a Marek's resistant strain in Australia?).

Strains of Marek’s vary considerably in their virulence. Some will cause a mild temporary paralysis; some will cause high mortality.

A bird with a mild case of Marek’s can recover, as long as s/he has food and water available thorough the paralysis stage, otherwise s/he'll starve to death. I've nursed a few back to health. Yes, they're carriers, but so is the wind.

Vaccination is mostly, but not completely, effective. Some birds might still contract the disease. Since the main conventional source of Marek's vaccine is a related turkey virus (turkey herpes), I've often thought that having an infected turkey around would be a good thing. Newer vaccines are GMO (like many pharmaceuticals these days). Home vaccination is possible. If I were selling chicks, I might try it; I've helped someone else do it, and it was pretty easy. However since I keep all my home-hatched birds, I'm happy to let natural selection take its toll, and only breed from the apparently healthy.

ipf, I did develop Barnevelders down there that were resistant. They are notorious in Oz for having terrible losses to Mareks. I had heart breaking losses when I started,and it is always the best birds, but at the end I had none.
The problem with vaccinated birds is you have to vaccinate forever. I started with vaccinated birds, cause the ones that weren`t didn`t last for long so most serious breeders were vaccinating. The problem is when you start to breed those vaccinated birds, unless you vaccinate the hatchlings, that is when you start to get big losses as the offspring has not inherited any natural resistance.
It is only about keeping the most healthy and the ones that survive an outbreak with no symptoms. I did not even try to nurse any through it, I only kept the ones that showed no signs at all. The first 3 years were very tough, but I had a great mentors that helped me see it through and I was very glad to have done it.
There are many different strains and mine would have been resistant to the most prolific in my area. Mine presented as `classic` Mareks. I had a very good breeder friend that had it present in a very different manner in her Blue Orpington flock. Hers basically would just waste away. They would eat, and act like regular birds and then just keep losing weight until they could not survive any long. It was Mareks as well, she had autopsies done on a couple of birds.
It is all a matter of choice, just like anything is. I happen to like a natural resistance instead of vaccinations, but others will argue the other is better. It is a difficult road, but one I would travel again if I had to make the choice.
Knowledge is power and then we make the choice that is best for us.

Did you manage to bring any of your Barnevelders to Canada? I know it's pretty much impossible to take birds into Oz, but is it as difficult getting them out? Could you bring hatching eggs? Did someone take over your flock when you left? I love Barnevelders. I had some thirty years ago, in a previous life, but when I came back to chickens 10 years ago, they seemed to have virtually disappeared; the ones I've found lay pale brown eggs, and lack the calm dignity of my old flock.

Sounds like you had a very nasty and virulent strain in Oz. I think I'm fortunate in that the strain I have here is very mild, and most of my birds are resistant to it. I hedge my bets by getting vacinated day-olds sometimes, but agree with you that breeding for resistance is a better way to go.

What have your experiences been with Marek's here?

I'm reading up on the pros and cons of vaccinating for Mareks. By the time my first chicks hatch early next spring I will need to have made a decision. Right now, I'm leaning strongly towards vaccinating.

I've have not yet had to deal with outbreaks of disease, but I realize this cannot last forever. I did lose 1 black Orpington pullet this year, and I suspect it could have been Mareks. She went lame, lost weight and finally died. lately I've been hearing and reading about lots of people losing chickens to Mareks.

One poor family lost all of the buff orpingtons they had bought from me as baby chicks earlier in the spring. 3 became sick and died. They took them to Airdrie Poultry Lab to be autopsied and verified it was Mareks. The vet instructed them to cull the entire flock to prevent possible spread of the disease! I don't know why they could not try to nurse them through and that way find out which birds had a natural immunity.
Unfortunately, the birds are all gone and I feel just awful, thinking this could have been prevented.
This Mareks just seems to be a real common threat, and one I'd like to do my best to guard against.

One thing that makes me uneasy is Coopslave's experience with vaccination. So it means that If I choose to start a Marek's vaccination program, I'm pretty much committed to continuing. And then I will be raising poultry with little or no natural resistance.
Maybe that is not a big deal, but it makes me feel a bit uncomfortable. However, if I am selling chicks that will go to new homes, I feel I need to try to give them all the protection I can.

I guess I'm just looking at this from both directions. I'd love to hear more opinions from other breeders ...do you plan to vaccinate? Or do you only intend to breed for natural resistance?

I am still on the fence with this one, trouble is my favorite breeds are known to be especially prone to mareks: dominiques, sebrights and silkies...

I like the disease resistance idea but very tough process I imagine, losing all those birds on the way...
haven't had much loss yet but sometimes those unexplained deaths could be I guess?

Kathy, I know what a hard decision this can be. I’ve thought long and hard about this myself and ultimately decided I will not be vaccinating for Marek’s (or any other disease) in my flocks.

I plan to breed for resistance in my birds by:

Culling (killing) any birds that become sick or show symptoms of a disease.
Only using birds 2 years and older in my breeding pool.

This means everything I want to achieve is going to take a whole lot longer, (groan) but will be better off in the long run as my future generations will be hardier (the first winter is always the toughest) and have inherited a natural resistance from their parents. You can’t buy that in a bottle. Just my opinion.

As for losses, yes, I expect to have some along the way, though that doesn’t stop it from being heartbreaking. I hate when my birds die or when culling becomes necessary. Survival of the fittest is not easy.


Also, I thought this was an interesting thread on the topic, even though their discussing breeding for resistance in general, not just for Marek’s. Many different opinions on the subject as you’ll see.

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I too believe in breeding for resistance. One caveat though, reading the last post in that thread, about killing all birds that display syptoms: remember that resistance is a continuum, and (as with people) there are those who never get sick, those who get mild cases and recover, and those who get very ill and may die. If you're starting with a breed that is highly susceptiple to Marek's to begin with, you may have NO completely resistant individuals. I'd suggest keeping birds that developed a mild case and then recovered, or one might end up with nothing at all.

And by the way, culling an entire flock to prevent the spread if Marek's is unnecessary and counterproductive, IMO. All flocks are likely exposed to Marek's; it travels on the wind. However, some strains are far more virulent than others.

This is a great thread to give information and alternatives to vaccinating for Marek's. I don't like to over vaccinate, however I did vaccinate about half of my chicks this year. Some of my chicks from last year were vaccinated yet I still lost 3 to marek's and a 4th that was vaccinated had a mild case and recovered although he still has an altered gait. Interestingly, all that were affected were roo's.

Here is a quote from the thread that FlickerChick posted a link to. This is pretty much how I feel about it too.

Breeding for resistance does not mean you let them become sick, then recover. That would just be setting up yourself for a very weak, immuno-compromised flock. Resistance means they DO NOT get sick because of their strong immune systems.

I prefer to use birds that never even get sick to begin with. I personally don`t keep anything that gets sick either. Just my personal choice.

BriarwoodPoultry wrote:This is a great thread to give information and alternatives to vaccinating for Marek's. I don't like to over vaccinate, however I did vaccinate about half of my chicks this year.

Briarwood, those 3 chicks that died last year were vaccinated, as well as the 4th? That does not sound like very good results. I do know the vaccine is not 100%, but I would not expect to lose 4 vaccinated chicks.
How are your chicks doing this season, with some vaccinated and some not? That sounds like a great way to determine how effective and worthwhile a Mareks vaccinating program is.

Yes, I read that too, and that is why I responded. Just because somthing is written in another (or this) forum doesn't mean it is true.

An individual that has been ill and has recovered is NOT necessarily immunocompromised. An immunocompromised individual is one with an immune system with little or no ability to fight infectious disease.


My point was that with the more susceptible breeds (and breeds vary considerably in their susceptibility to Mareks, as I'm sure you know) there may be few or no individuals with total resistance. One that fights off the disease at least has partial resistance.

Aside from a few 'normal' chick deaths I haven't lost any except 2 chicks I bought to cocci, and had to cull a couple that hatched with very bad spraddle leg that got infected. I think my oldest chicks are now in the "mareks susceptable" age. The oldest were all unvaccinated as I didn't have the vaccine info until later this spring - hence why only half my chicks were vaccinated - I lost 3, freaked out and vaccinated like mad. Now I'm second guessing why bother vaccinating if it was only the vaccinated chicks that died (as older chicks).

Of note, the chicks I lost were 2 types of marans, and orpington. All roo's. All vaccinated as day olds. I have other poultry that was similar age, heritage, some pure some crosses that were never sick. I have some that were vaccinated and are completely fine. I have never had a problem before this year, so I'm wondering if it was a bad year in the wild bird population.

Err.. that's clear as mud I realize... sorry I can't be more concise. I wonder if the vaccine's aren't as well developed as such vaccines as parvo for puppies.

Well this thread sheds some light on a mystery of mine.Last winter I had two young buff orpington roosters that developed an odd, stiff-legged gait. I had no idea what it was or if this was just a peculiarity of the breed. One recovered and is now the Boss and the other always kept his funny walk.I guess now we'll see how the PC's do with it. Any one know how their(the chanties') resistance level is?

coopslave wrote:Here is a quote from the thread that FlickerChick posted a link to. This is pretty much how I feel about it too.

Breeding for resistance does not mean you let them become sick, then recover. That would just be setting up yourself for a very weak, immuno-compromised flock. Resistance means they DO NOT get sick because of their strong immune systems.

I prefer to use birds that never even get sick to begin with. I personally don`t keep anything that gets sick either. Just my personal choice.

^ That is exactly how I feel. Breed for resistance now and secure immunity in the future.


Ipf: I concede your point when working with a breed with a well known low intolerance to Marek’s. You have to start resistance building somewhere and some is better than none. But is it really in the long run? What if your entire flock comes down with the disease, doesn’t that speak of a crack in your starting foundation, a weak immune system? And why are certain breeds more susceptible to Marek’s anyway?

Gah. Sorry for hammering you with questions there. I just find this subject really interesting.

And no, I do not believe everything I read. Not unless it’s on TV too. Just kidding. We don’t even have cable. It’s all about movies here. But seriously, all info is digested with a grain or two of salt.

I mentioned this before. I had two vaccinated chicks contract the leg paralysis thing, mareks, one pullet, one cockerel, both buff orpington, the birds had been brought up from the coast as 11 week olds. One of the three, a pullet, survived, her siblings did not, she is as different as night and day from them. This pullet was always almost 1/2 again the size of her sibling, she is huge and I hope that she will have great immunity to pass on, I think she is a very promising gal with type, etc.

I had two other buff orpington cockerels from one of my hatches contract the paralysis of markes, unvaccinated, culled.

I had one black cochin that contracted the paralysis of one leg, a cockerel, the bird died suddenly, overnight.

I had another black cochin contract the paralysis of one leg, a cockerel. Seems that cockerels may be more susceptible to it and that in my flocks, it is the buff orpington and the black cochin.

That is the extent of my losses with marek's virus. And I have raised a good many chicks this year, the gold laced wyandotte and buckeyes don't appear to be affected by the disease. Just a couple of thoughts here.

I have a different line of buff orpingtons now, they are 9 weeks old. Time will be the teller of the tale if they make it or not, without contracting the disease. But I am thinking the buff orpington lines that I had did not have the best immunity to marek's. I will be getting rid of my other line of orpingtons, when the new line becomes laying age, I need the eggs the older gals provide consistently, great winter layers. Have a wonderful and great day, CynthiaM.

I am just wondering out loud and this is not reliable information.
Because there are many different strains of Mareks may be the reason some vaccinated youngsters still come down with it. Does anyone know if the Mareks vaccine is like the flu vaccine for people, they just take a educated guess what is going to be the most active strain and vaccinate for that?

I know Orpingtons, some lines of Wyandottes, some dark Indian Game (are they called Cornish here?) and Barnevelders down in Aus were some of the breeds that were more suseptable. Even when I started playing early on with my Barnie x Ameraucanas, they were a little sensitive to it as well.

I have not has any trouble with my Partridge Chanteclers. I believe the ones I started with were vaccinated as day olds (last year) but anything I hatched this year has not been and they are all fine (fingers crossed). I am interested in the Ameraucanas though. They have been bred a bit tighter, so we will see what is up with them as they year goes one.

From what I am hearing so far here it sounds like some Orps (doesn't surprise me) and some Marans are showing a bit more sensitivity to it. Anyone else having other breeds that seem to not respond well to it? I think certain areas can have more trouble with it as well.

I am enjoying the discussion and hearing peoples ideas and experiences with this!

There are a number of different vaccines developed over the years, from the earliest one, made from the related turkey herpes virus, to the most recent, widely effective, GMO one. This are many different strains of Marek's disease, too, and some of these are resistant to the turkey-herpes vaccine, so a vaccinated bird might come in contact with a more virulent strain.

It's also well documented that the vaccine sometimes just doesn't "take" on individual birds, so a vaccinated bird could still contract a strain that the vaccine should be effective against.

I think, but am not certain, that exposure to one strain of Mareks stimulates immunity to other strains. I'd love to know if anyone knows more about this? If this is true, then exposing your flock deliberately to a mild strain will protect your birds from more virulent strains. I'm virtually certain that I have a mild strain in my flock; I've lost a few birds, but very few.

No, the vaccines aren't targetted to individual strains on a yearly basis; Marek's isn't like the flu virus where one strain dominates in a given year.

ipf wrote:There are a number of different vaccines developed over the years, from the earliest one, made from the related turkey herpes virus, to the most recent, widely effective, GMO one. This are many different strains of Marek's disease, too, and some of these are resistant to the turkey-herpes vaccine, so a vaccinated bird might come in contact with a more virulent strain.

It's also well documented that the vaccine sometimes just doesn't "take" on individual birds, so a vaccinated bird could still contract a strain that the vaccine should be effective against.

Thanks for that info, stuff I was to lazy to find out for myself!

ipf wrote:I think, but am not certain, that exposure to one strain of Mareks stimulates immunity to other strains. I'd love to know if anyone knows more about this? If this is true, then exposing your flock deliberately to a mild strain will protect your birds from more virulent strains. I'm virtually certain that I have a mild strain in my flock; I've lost a few birds, but very few.

I am not sure about this. I had a friend take some of my Barnies when we moved back here. I had not had losses to Mareks for 4 years or so, but I know she had had far more trouble than I did with it. Her strain seemed to be a lot worse and more devestating than mine. I know the first year hatching from my birds she had a few losses, not as many as she usually did bringing in a new breed, but I think this year she has had none so far.

ipf wrote:No, the vaccines aren't targetted to individual strains on a yearly basis; Marek's isn't like the flu virus where one strain dominates in a given year.

I assumed that may be the case. These thoughts I have bouncing around in my head don't often amount to much!

One thing I have comment on, regarding different breeds and their resistance to disease. I hatched 39 white Chantecler chicks this season. Out of those chicks I did not treat or cull a single one for health reasons. (touch wood!!) The youngest are now coming up to 3 months old.
I had to put down a couple of cochins for leg issues and I treated a few Orpingtons and Wyandottes for runny eyes. Had bumblefoot in 2 Orps as well, and the one I lost to (maybe Mareks) was a black Orp. Not a single problem in the Chanties, so I think that speaks for some good resistance in the breed.

Another comment I'd like to make here. I know people say that Mareks is everywhere. But I believe environment plays a big factor in whether a bird will become sick. Those chicks that left my farm traveled only 1 hour away. I saw pictures of them in their new home...new tractor with clean grass, clean water and good food. They had the best of care, but still became sick. The buff orpingtons that I kept on my farm (same lines, same parents) did not come down with Mareks.
Something in the air? Or more likely there were other, older chickens on that farm that were not sick, but were carrying the virus.

By "environment" do you simply mean "location"? Sounds like both environments are good healthy ones. When saying environment plays a big part, we usually mean with respect to environmental conditions that differ between the two (or more) sites.

Other possibility in the case you describe is different strains of the disease "in residence" - you have a mild one and they have a more virulent one? Support for my theory. . .

My BCMs and mixed breed banties have been hard hit. I also have a 12 week old orpington come down with it so I expect to see losses there as well. My Ameraucanas/EEs (almost 3 months old) have not shown any signs of illness yet.

Its been 5 days I think without any new birds showing signs of illness. I don't expect this to last but I'm still hopeful.

My question is - if I lose all the hens of a specific breed - would it be best to hatch more next spring or purchase older birds?

Coopslave, I would like you to account which strain of marek's in Australia was the most prevalent. What were those symptoms? I have encountered only one form of the disease, and that was paralysis of a wing on one side, which quickly moved down to the leg, the entire side of the cockerel was paralyzed before I figured out what it was. I have recounted this before. It was that buff orpington cockerel that was vaccinated. The other buff orpington pullet did not get the dropped wing, only the leg paralysis.

I did encounter, what I know believe to be marek's with one of my buckeyes, when she was about 11 weeks old. I am still not certain of it, but she seemed to get what I would call a greyness to her eye. Otherwise very healthy. I did suspect marek's at that time and was not going to take any chances with it becoming a spreading issue. I culled that pullet. Tough love. So I must take back what I have said about the symptoms, I did see one, and only one ever, with what probably was a different strain of the disease, the grey pupil, looked very awful and it made me very sad, as I felt that need to cull.

Please clearly define what was the most common symptoms of the disease that you dealt with in your old life, that would be a good thing to hear and understand. have a beautiful and wonderful day, CynthiaM.

Cynthia, the different strains are not necessarily differentiated by symptoms, but rather by the genetics of the virus. Not something you can identify readily.
Also, once your bird has symptoms, culling it isn't going to prevent spread; she's contagious, and the virus is there. I'd have let her be and waited to see if she recovered; culling will do no good.

Previously, we have kept chickens with and around turkeys and in those days I never experienced any marek's at all. I now have a couple turkey poults in with my last batch of unvaccinated chicks... will be interesting to see how that goes.