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All You Need To Know About Marek’s Disease

All You Need To Know About Marek’s Disease Blog Cover

Marek’s disease is an insidious ailment that catches many keepers by surprise.

Its effect on your flock can be devastating.

Many keepers are lucky to go a lifetime and never see this disease, even though it is widespread.

To find out if it is endemic in your area, call your local extension office; they should be able to tell you if it is present near you.

We’ve already discussed Marek’s in the past in this article about Guide to Chicken Parasites.

However, there’s just so much misinformation circulating about this, so this article will clarify matters for you and your birds.

I have written this article in a question-and-answer format as this is the easiest way to convey information about this complex disease.

Also, I encourage you to read, read, read!

There is a lot of information out there to know about Marek’s disease.

And concerning vaccines, it seems to be constantly changing.

Just remember, if in doubt, please get in touch with your local veterinarian or extension office for help.

All You Need To Know About Marek's Disease Infographics

What is Marek’s Disease?

Marek’s disease is a viral disease of chickens caused by the herpes virus. 

Current research shows that the virus has six mutations that can cause the disease.

Depending on the strain Marek’s disease caught, the virus can range from non-pathogenic (not causing disease) to highly pathogenic (causing illness and death).

It was first noted by the brilliant Hungarian veterinarian Jozsef Marek in 1907.

When he wrote his paper about it, it was likely that only one strain of the virus existed; however, other strains have mutated since then.

Reputable sources currently say that Marek’s is so widespread that you probably already have it in your flock, or your flock has been exposed already.

But don’t panic just yet!

Reading about the disease and understanding it will help guide your decisions and treatment.

What Are The Signs of Marek’s Disease?

Some birds do not show any ‘symptoms’ of disease.

They may simply resist it, or the type of virus caught may be non-pathogenic (not causing disease).

It should be noted that there are four different presentations of Marek’s disease: Neurological, Ocular, Cutaneous, and Visceral.

The type of presentation will dictate the kind of signs that you will see.

Signs for each form will vary.

Some birds display all signs, others not so many.


The neurological form of the disease is the most notable and disturbing in its presentation.

The symptoms are mainly caused by lesions affecting the nervous system, and several other problems usually follow.

Occasionally the affected bird will have temporary paralysis, resolving itself spontaneously.

  • The bird shows progressive paralysis, usually in the legs or wings. Often the bird looks like it’s doing the splits.
  • Twisting of the head to one side or backward.
  • Respiratory problems such as labored breathing.
  • Darkened or purple comb (lack of oxygen).
  • Diarrhea.

Marek's Disease

Ocular (Eye)

  • Graying of the eye color.
  • Misshapen iris.
  • Blindness.
  • Non-reactive pupil of the eye.

Cutaneous (Skin)

  • Lesions around the feather follicles.
  • Ulcers and/or scabs around follicles.

Visceral (Internal)

Often the only diagnosis of visceral Marek’s is, sadly, post-mortem due to internal maladies.

  • Cancerous tumors grow inside the bird on the organs.
  • Weight loss.

It’s also very likely that your chickens will stop laying eggs during this time.

How Do Chickens Catch It?

The virus is primarily spread by infected dander (dead skin cells) from other birds. 

However, it can be transported in dirty hen carriers, clothing and boots, wild birds, and darkling beetles in the henhouse.

It can survive for up to 65 weeks in ambient temperature in coops and for years in the soil.

The virus is spread horizontally — from chicken to chicken, not from the hen to the egg.

And it spreads quicker among hens in tight living conditions. So make sure your hens have enough room!

The primary age for disease manifestation is between 5-25 weeks, but this does not mean that older birds will not suffer from it.

It just means that younger birds are more susceptible.

How Can I Prevent Marek’s Disease?

Vaccination of chicks will help lessen the severity of an outbreak if it should occur.

However, the vaccine does not prevent the bird from getting Marek’s.

The vaccine allows the bird to build a better immunity to the disease, though.

This means a reduced likelihood of severe symptoms or death and the spread of disease if an outbreak occurs.

Part of the problem lies in the fact that the virus is constantly mutating, similar to the human flu virus.

Your birds may be vaccinated against one strain of Marek’s but not the one that infects them.

Another way to prevent the spread of Marek’s is not to add any additional hens to your existing flock.

Few backyard keepers do this.

We are drawn to getting new birds periodically, making it a challenge to keep Marek’s out of your flock effectively.

If you are compelled to add additional hens to your flock, ensure that new birds come from a reputable source that strictly practices quarantine. 

You should know that Marek’s does not always show up in quarantine.

So even with rigorous measures, it is possible to bring Marek’s home with you.

As always, good housekeeping, biosecurity, and ventilation are essential tools in your fight against the disease.

Marek’s virus is resistant to some disinfectants such as Phenol; however, many keepers recommend using Oxine.

This kills the virus and has very low toxicity to the environment.

How Can I Treat Marek’s Disease?

Unfortunately, there is currently no treatment/cure for Marek’s disease.

Depending on the severity of the disease, some birds can be conservatively managed and do not require culling.

However, they will remain carriers of the disease for the rest of their lives.

Are all birds affected?

If one bird in your flock gets Marek’s, all will likely get it.

However, not all will show symptoms or experience disease.

Birds that have been vaccinated have higher immunity.

Still, birds that have a weak immune system or some other ongoing health issue will probably succumb.

The virus enters a ‘sleeper’ mode in infected birds with strong immunity or resistance.

It will insert itself into the bird’s RNA sequence and lie dormant.

If the bird becomes immune suppressed later in life, the virus may emerge at that time, causing symptoms.

Should I Vaccinate My Birds?

This is a very personal decision.

If you want an entirely ‘organic’ flock or generally dislike vaccines, be aware that there will be a significant loss if Marek’s attacks your flock.

The birds that do not die from it will be carriers for the rest of their lives, so you should not sell, give or loan your birds to other flock owners.

If you choose to vaccinate, you may still have losses.

Some flock owners have had chicks vaccinated at the hatcheries only to have them die later from a different strain.

Remember: vaccine does not guarantee immunity.

If you show your birds, vaccination is highly recommended.

Your girls will likely be in contact with other hens, and the likelihood of them catching Marek’s is significantly increased.

Many keepers and poultry people recommend that you do vaccinate since Marek’s seems to be very pervasive.

If it is endemic in your area, it would be prudent to vaccinate.

If you have older birds that have not been vaccinated, it is possible to vaccinate them at any time.

However, this can become an expensive prospect, and as noted before, the vaccine will not guarantee immunity.

When Do Chickens Show Signs of Marek’s Disease?

Unfortunately, some chickens may never show signs of the disease, and each type of Marek’s disease can present itself differently.

For example, the neurological form typically has an incubation period from 3 to about 30 days after exposure.

Can other Birds Get Marek’s from My Chickens?

Typically, Marek’s disease is mainly a chicken disease.

Still, some sources state that it can spread between different types of birds.

As you may know, it’s better to be safe than sorry.

So consider keeping birds like quail away from your chickens since they can catch other diseases.

There are plenty of other diseases that can be passed from one species to another, so erring on the side of caution is never a bad idea.

Other FAQs about the Marek’s Disease

How do I know if it’s active in my area?

You can start by calling your local extension office. They should have the information.

Also, talk to the chicken people in your area; they are always a mine of information!

If they have been bothered by Marek’s, ask them where they got the chicks from…

Can I catch it? 

No, Marek’s disease is not contagious to humans.

Can I eat the eggs and meat from an infected bird?

The virus does not travel to the egg from the mother, so the eggs are safe.

Just make sure to clean them properly.

Meat from an infected bird can also be eaten as long as it is properly cooked.

But frankly speaking, we wouldn’t recommend it.

However, chances are you won’t be able to anyway because infected birds should be incinerated to prevent the disease from spreading.

How do I know if my hens have Marek’s disease?

The only way to know for sure is to have a laboratory test and evaluation by a veterinarian.

However, if their symptoms match those mentioned earlier in this article, they likely have Marek’s.

Marek’s Disease In A Nutshell

Marek’s is a pervasive disease that is widespread amongst chickens.

It is a cancer-causing virus and, as such, is being researched constantly because of the implications for human treatment.

As a virus, it constantly mutates and presents an ever-changing challenge.

The vaccinated bird is somewhat protected, but unvaccinated birds can be in danger of succumbing to a more contagious strain of the disease.

It is difficult, if not impossible, for the average backyard chicken keeper to keep Marek’s out of their flock.

Unfortunately, some devastating experience consequences when the disease emerges, but for most of us, the impact is minimal.

Keeping your flock healthy, practicing good housekeeping, and strict quarantine practices will all help in the fight against this awful disease.

Want to learn more about chicken health and other possible diseases? Check out our recommended reads below!

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109 thoughts on “All You Need To Know About Marek’s Disease

  1. Hopefully you can help. Thank you for all the info, it’s very helpful. I’m not sure what to do with my sebright though. She has the signs: paralysis, heavy breathing, dropped head, falling around when trying to move and looking like she’s going to die any minute. That said though, give her attention and she’s still perky and goes mad for her meal worms
    She also has a very hard disc shaped lump in her chest which is protruding. I’m close to culling her but she still has that sparkle in her eyes so here’s my question: you mentioned “temporary paralysis”, does that mean that she could pass this phase?
    She’s been like this for 2 days and progressively worsened. Thank you for any advice.
    Also, I’m giving water with vitamins by syringe and she only eats a little.

    1. Hi Brian,
      So sorry to hear about your sebright 🙁
      In my experience the paralysis doesn’t ever get ‘cured’.
      By temporary I meant that it will come and go.
      Hope this helps clear it up for you Brian and sorry again for your sebright,

    2. What you’re describing is exactly what my lovely buff orphington is doing now. She has almost no control over her neck but I hate to put her down since she’s still alert. She doesn’t appear to be in any pain.
      How did your sebright fare?

      1. I just lost an Easter Egger to Marek’s. As she began to exhibit these same symptoms I isolated her from the rest of the flock. She lasted about two days before passing away. Sorry.

    3. Brian, I know this is an old post, but you described my Blue Sapphire “Bubbles” to a tee! She is unable to walk and uses her wings to balance when she does stand up, then lays back down, or pitches forward and falls down. It’s so heartbreaking! But…she loves to be cuddled, is eating scrambled eggs, meal worms and some crumbles, and drinking with a syringe. I know this is no quality of life for her, but she’s so bright eyed, and “coos and purrs” when she is held…She has been like this for 2 weeks now. We have a flock of 10, 9 so far are ok, but watching them closely. I removed her from the flock as soon as I noticed she was a little “off” (She was the smallest, and I thought she was just being picked on) Fingers crossed no others become sick.

      1. This is exactly how my little Leia is. She has such a sparkle in her eye, and Kus and purrs in my arms. I feed her both her seed and water through syringes. She’s even gain some weight back from this method. I just don’t know if she’s in pain or not. I haven’t been able to find an answer on that. She doesn’t seem to be, but I don’t know.

        1. I only have had chickens one year.
          Just had to cull a 4.5 month old. He could not stand and as the weeks went by his legs sprawled more. He was bright eyed, cooing whenever i visited him and feed and cleaned. He didn’t seem to be in pain. My HOPE was for recovery.

          After culling him, i compared his joints where the “drumstick” meets the thighbone (the hock?) to another of male the same age. The sick bird i just culled had VERY SWOLLEN joints relative to the healthy bird. It had to be painful for the bird even though I gave him aspirin. I know that as people age, joint swelling causes pain and eventually deforms the joint. Therefore, I am guessing that the mareks disease causing swelling pinches nerves and creates deformity, the legs to splay out… and it must be painful.

          In future, i will observe a bird for 2 or 3 days to make sure it is not an injury (sprain, or cut) that can heal. But if it appears to be Mareks, i will cull before a week. My bird must have suffered too long.

  2. This is my first & amazing experience with chickens & I am seeking some help. I have 9 hens & a rooster.. 25 weeks old. A few days ago, I noticed one of my Wyandotte hens turning her head sort of sideways to take food from my fingers, something I don’t remember her doing before. I spend a lot of time with them, so I did note this without really any concern. But today, I did notice one pupil a lot larger than the other & with watching her, I believe she is blind or partially blind in the eye with the larger pupil by the way she seems to be looking at things. She seems fine otherwise. Maybe I’m looking too hard for something, but she might be picked on a little bit by a couple of the other hens that I don’t recall before? She is my friendliest girl. Anyway, should I be concerned? I googled this & only came up with ocular Marek”s disease. Now I am worried. There seems to be clarity in her eye colouring but a very distinct difference in pupil size. I do not see it in the others. Can this be a natural fluke just for her & not this disease? Thank you for any reassurance or advice..

    1. Hi Judy,
      Thank you for getting in touch with me 🙂
      The first thing to note is Mareks is a very aggressive and contagious disease- so I think it’s very unlikely that she has Mareks as the rest of the flock would have it too…
      In terms of it being a ‘fluke’, I have seen hens before that are blind in one eye and live perfectly normally lives.
      Have you tried examining her in more depth, covering each eye in turn and using treats to track her eyes?

      1. Hello, I am experiencing Marek’s in my flock. Their coop is in a very old barn with dirt floors, so I can’t truly disinfect the coop. It looks like I can expect to lost over half of them. Going forward, how can I try to get chicks that will hopefully have the vaccination to increase their survival rate? This is devastating to a flock.

        1. Hi Christy,
          I’m so sorry to hear about your loss. Yes going forward you can actually buy chicks that have already been vaccinated, so that’s what I would recommend.

      2. Thank you kindly for your response Claire! 🙂
        Yes, I have examined her very closely & frequently. She is my friendliest girl so follows me around the most & is pretty easy to hold. I believe she is totally blind in her eye with the very large pupil. The pupil is non reactive to both movement & light & the gold iris is somewhat lighter on the blind eye.. but still coloured (not grey). Both eyes used to be the same.
        She turns her head one way all the time to see. It seems to be fairly sudden. What can cause this if it’s not Marek’s? 3 of my hens pick on her more than before like they know, but she still fits in on a bit lower order.
        I am not worried about the blindness so much, as it happens that I adopt special needs animals & comfortably deal with blindness. I am just worried about a contagious disease & my flock that I love. This is my first experience with my own chickens & want to do right by them.
        I appreciate any ideas or opinions you may offer.
        Thank you so much.. 🙂

        1. Hi Judy,
          Ah ok I see- I thought she was born like this, but it is concerning that it’s only recently happened.
          It could be caused by many things, including Marek’s, an injury or an infection.
          Without seeing the hen it’s hard to say, but I would definitely take her to your vet sooner rather than later.
          Let me know how you get on,

          1. Hi My name is Melissa, I have a chicken that from her symptoms seems like Mareks. She is now almost completely paralyzed which started with the splits as described. What should I do? wait? its been almost a few weeks. I read here that it is sometimes a temporary paralysis. Please advise! I feel so bad for her and void of what to do.

          2. Hi Melissa,
            If you think it is Marek’s then I would contact your vet ASAP.

        2. I have what appears to be mareks, I took one to vet and he concurred, I have lost two so far but two more that were in bad shape have survived and are up walking and trying to fly, my question is can I put them back in the pen with the other healthy chicks,

    2. Hello Judy,
      How is your hen doing now?
      I have the same thing happining to me right now. My hen in from spring of 2016 and she is a black and white laced wyandotte.
      Iam now wondering is this could be related to the genes as I saw another case with the same breed of chicken and color. I went wild thinking it was mareks myself. How is everything now? What state are you in? I am in north east washington.

      1. Hi Kat. Are you in Spokane? I have never had any problems with my chickens but suddenly may have Marek’s in one pullet. I have been so careful…very disheartening. C.

  3. I have a 4 month old cockerel who suddenly can’t stand up . Hes been like this a week and 3 days. The vet couldn’t see any injury and put him on metacam. He said if no better this week probably best to call it a day. He is eating and seems ok in himself. I booked an appointment at the vet to do the dead when suddenly he was standing up again and managed to walk over to a treat. Greta I thought hes getting better so cancelled the appointment. Next morning can’t walk again, in the evening he could again this morning all over the place again. He is still eating and cockadoodling. Do you think this is mareks? So far all the other chickens are ok . I did buy in 3 new girls at the beginning of October. Any suggestions about this boy? Could he get better? Thanks for any advice

    1. Hi Rosie,
      Sorry to hear about your cockerel.
      Without seeing him I can’t really say whether it is Marek’s disease or not sorry.

  4. We had a four day and a one day old silkie chick. Last night our four day chick died from what seems to be Marek’s disease. We haven’t vaccinated the other one yet but if were able to vaccinated it will that help for it to survive. I can’t stand to see another baby die like that.

    1. Hi Shane,
      If your four chicks had Marek’s, I would get a vet to check your surviver ASAP. If they haven’t caught it already then they could be vacinated to protect them.
      Sorry to hear about your loss,

  5. Hi Claire,
    I’m thinking our little girl has Mareks. She has been paralyzed for 4 days now. Her little body doesn’t move but she will drink and eat. Her little head moves and she seems in great spirits. I feel so bad that she just lays there. Is it best to put them down when they get this? We only have 6 chickens. The other 5 seem fine. We quarantined her the first day. Any advice is greatly appreciated?

    1. Hi Debbe,
      Sorry to hear about your little girl 🙁
      Without seeing her in person it’s hard for me to say. I would get a local vet to see her ASAP.

    2. Did anymore of your chicks get sick? I think I am dealing with mareks. Second chick in a week that has lost use of one leg. This is my first time owning chicks, I am so sad.

    3. My 24 week old pullet got Marek’s. she has been sick for a week and is dying. I quarantined her as soon as I noticed the symptom. My other chickens look fine so far. I hope they have built up resistance. I have been doing everything I could to make her comfortable.

  6. Lost one hen just got droopy and wouldn’t eat. The rooster laid with her found them both dead 2 days later. Have one Welsummer now just sitting but can move around but doesn’t want to eat much one eye has been cloudy for months thought it was an injury. How do I protect the rest of the flock

  7. I have a 6 week old pekin frizzle bantam and yesterday he suddenly became really lethargic. Yesterday he just stood with his eye closed, not eating or drinking. I have been giving him warm molasses water with a spoon. This morning he is even less active. He is now laying down and seems unbalanced if he tries to walk. He just seems really weak. I took him to an emergency vet centre last night and the vet said he could feel a bit of hardness in his chest and mentioned Marek’s disease but couldn’t confirm anything without further testing. I am really worried about him as he is not eating anything and cant drink on his own. I have two chicks and they are best friends and the other would be devastated if he didn’t make it. Is there anything i can do to help him/ boost his immune system? I don’t know where he might have caught Marek’s from and it all happened really suddenly.

  8. Thank you for this article. We believe ours became infected with Mareks disease when we brought home some new ones to our flock. We are devastated. Going forward we would like to know how to begin again? Do we need to do anything special for cleaning coop/new feeders?? Thoughts? We had 25 chickens we are down to 10 in a very short amount of time. Neurological seems to be the issue. Thank you.

  9. I had three Legbar pullets in an old coop that had not been used in a while in order to transition to the flock in the larger coop.
    Two of them died of Marek’s and the third never showed symptoms. It has been a month since the two pullets died.
    Can I move the remaining pullet into the main coop safely? Will my 1-2 year old chickens be in danger of Marek’s?

    1. Hi Matt,
      As mentioned in the article it can last up to 65 weeks so personally I wouldn’t risk it unless your other hens have been vacianted…

  10. Hi,
    it’s me again. I did some research yesterday and went through photos present in internet related to the symptoms of the Marek’s Disease. Unfortunately I am 100% sure that I am experiencing Marek’s Disease in my flock of silkies 🙁
    My question is, knowing that this virus can survive 65 weeks, is there any chance to clean somehow the place where my ill chickens are. Does this virus stay deep in the ground? (My silkies are in a wooden aviary, not a building with floor). Is it possible to get rid of the virus by exporting few cm layer out of the aviary, or to powder the ground with some cleaning powder?
    And what about the rest of silkies, those without symptoms, shoud I put them down? If I decide to have them, will I be at risk to pass the virus on my shoes or clothes to other birds I have in different aviaries?
    Thank you for your time and reply.
    I hope my description of the symptoms I experienced in my flock will help others to understand what is going in their flocks when they happen to, unfortunately, meet the disease.
    Best regards,

    1. Hi Karo,
      I’m so sorry to hear about this!
      Please send me an email and I will do my best to help 🙂

  11. So I have lost two to Mareks. I have one girl left. All three were vaccinated. Going forward what should I clean with and if I wait 65 weeks can I safely restart my flock?

    1. H Dei,
      This number is provided as a general figure to give you a rough indication.
      If possible, I would recommend raising chickens in a different location to be sure. How much land do you have, is this possible?

      1. Several people have asked about cleaning the coop, moving to a new coop, and/or waiting and starting new flocks. However, it sounds like they have chickens that survived Mereks. I think people do not realize the surviving chickens are carriers. Those birds are strong and have good immune systems. Personally, I think we should be preserving such chickens. And I do know of flocks in endemic areas with resistant strains–not 100%, but good resistance for the homesteading situation or backyard flock. For my own flock I get vaccinated chicks–Mereks is very common in our area and wild turkeys frequent our yard.

  12. Hi,
    I got chicks last spring and was told that they were “flock vaccinated” – I bought them at my local farmer’s union, ordered from a hatchery. I got 21 chickens, and of those original 21 I now have 6 left. I did send one for necropsy and it was indeed Mareks. The remaining birds seem to have survived the disease and are laying eggs regularly, but although acting healthy in all ways they seem to have diarrhea most of the time. No weight loss or other symptoms. I’m wondering if I can add vaccinated chicks to this flock? I’ve considered just building a new coop an acre or two away on another part of my property. Any suggestions? Thanks!

    1. Hi Rene,
      The important thing is the vaccination doesn’t give them immunity to Marek’s- it just gives them a better chance of surviving if they catch Marek’s.
      Hope this helps,

  13. Hi I think my flock is infected. I lost 3 hens to what I think is mareks before October and now I have another hen who is experiencing the same symptoms. I did notice in her that she has one dilated pupil. Is it normal that there will be a lull in them showing symptoms? They are now about 40wks.

    1. Hi Anna,
      It’s not normal but certainly possible.
      Did you get a post-mortem on your other hens to identify the cause of death?

  14. Hi my name is Paul and I live in France, a year or so ago see dicided to get a few chickens and a couple of geese.
    One day thee make goose developed a limp, after a day or so it became difficult to walk, the next day I found him in the coup laying on his back with his neck twisted back, the next day he died.
    A while after I noticed one of the chickens limping luckily this only lasted a couple of days and she was ok after. Then later that week I found 3 chickens hobbling about 2 began to shed thier feathers and later died the other recovered. We also had 2 pantards ( very effective a keeping foxes away) again the developed the same symptoms, one died and one recovered.
    I have no idea as to the cause until last week, last summer we brought a young peacock, he has grown and eventually got his wonderful tail feathers. He has lived in a separately but in the same vacinity as the chickens. Yes you guessed it he caught the same symptoms, I called the vet and he immediately diagnosed Marek’s Disease which ultimately lead me to your sight which I have found very helpful and informative.
    Thank you

  15. Hi
    I noticed one of my 4 month old chicks struggling to walk after I came home.
    The other chickens all seem to be fine and can walk normally.
    I am keeping her seperate from the others but I’m not sure what to do. I’ve been reading on what it could be but all I seem to find is that it’s possibly mareks.
    Do I have mareks in my flock?

    1. Hi Alex,
      It’s certainly a possibility.
      However, without being there in person it’s hard to say. The only way to know for sure is to bring a vet in to test her.
      Best of luck,

  16. We have an 11 month old Serama that started with some diarrhea and just not herself a few weeks ago. We brought her in the house and are keeping her separated from the others in a dog crate. We noticed that she can’t use her one leg now. Our rooster has been really rough with her lately (we only have 2 hens and a rooster) Her original mate passed in December from what we are not sure but could be the same thing. She is eating and drinking. We had her on a 5 day regime of Corid. I am not ready to give up on her. I have read that B12 can help. My husband thinks she is not going to get better. We don’t really have any poultry vets in our area. She is a sweet little thing and I hate to give up on her already. Any thoughts? Thanks.

    1. Hi Karen,
      I’m really sorry to hear about your Serama.
      The main thing is making sure she isn’t in any pain. As long as her condition isn’t continuing to deteriorate then you have nothing to lose.
      Make sure to read our 2 articles on caring for sick/disabled hens.
      I have my fingers crossed for you,

  17. I see you had requested someone to email you on the proper way to sanitize after a Mereks disease out break. Could you please do the same for me PLEASE!

  18. Hi and thank you for this article you shared. It’s very helpful.
    My first and favorite broodcock, I think, caught Marek’s and his left eye has gone blind with its pupil turning smaller.
    My question is – would his left eye see again if he survive the disease? I didn’t put him down. I pity him a lot as he’s a favorite of mine. I also understand that probably all my flock has the Marek’s, I intend to stregthen the immunity of my flock by breeding Marek’s survivors. So I’m really hoping my favorite broodcock will survive and will also get his left eye vision back.

    1. Hi Aldwin,
      If I’m being honest I’m not entirely certain. I would contact your local avian vet who will be able to advise you 🙂

  19. I have a small backyard flock. 7 hens ranging from 1-4 years old. Over the past month I lost 2 of my 4 year old hens. Based on their symptoms it sounds like Mareks. Is that likely since they were much older than when it typically manifests?

    1. Hi Briana,
      It’s certainly possible. Did you get a postmortem on your hens to identify the cause of death?

  20. Hi! We have 35 chickens and 2 have died so far from mareks. They are in an old barn with a makeshift run right now. Would it be of any benefit to move them all to a different coop/ area?? Trying to think of any way to lesson the chances of losing them all. Thank you!

  21. Hello! We had brought home some day old (hatchery) chicks.. We didn’t realize that they had been vaccinated for marek’s, until I noticed a dot on the back of one of the chicks necks. They were added to a brooder that had 1 week old chicks in it. They were together for 1.5 hours. The brooder is INSIDE our house, I seperated all the new chicks from the 1 week olds. How likely are these 1 week old chicks to become infected, as they are NOT vaccinated.

    1. Hi Naomi,
      It’s very hard to say without knowing exactly what the hatchery chicks were injected with. If you are concerned I would contact your local vet who will be able to check for you.
      Failing this, you can closely observe your chicks as they develop and look for any symptoms which are mentioned within this article.
      Best of luck,

  22. Hello! Yesterday the kids noticed one of our pullets, 5-6 months old, dragging her toes before she took a limp step. Sure seems neurologic. Was lying down more than usual. Today, she is exactly the same, no progression. She limps on the one leg, dragging her toes to catch up. She can still perch and get around. Her eyes are bright and clear. Seems healthy otherwise. Should Marek’s progress quicker than this? She’s on great food, so I’m certain she’s not vitamin deficient.. let me know what you think. I just don’t know how far things should change for the worst if it is Marek’s. She, along with 15 others her age, we’re added to our existing flock of 15 which has been vaccinated. She and she most of the other new ones have not been vaccinated. Nobody else has symptoms. Thank you!

  23. Hello, I have been monitoring my flock for a while and I can observe them twisting their heads to odd angles whenever they are looking at something. I don’t know if this is normal behaviour but it is concerning me. Does anyone reckon my flock is infected?
    Good Chickenery,

  24. Hello! Thanks for such a helpful article!
    I have 2 Golden Comet hens and one of them was turning her head upside down for about a week and then stopped she seemed mostly fine, but now she’s acting weird. She doesn’t seem to be able to see very well whereas shes walking into things. She has a lot of feces on her bottom which I’ve tried to give her multiple baths, but it comes back. She tucks her tail sometimes too. It’s November and she also seems to be molting! Her pupils seem fine as far as I can tell. Sh doesn’t seem to have difficulty walking… Just finding her way. In addition, she usually fly/jumps to the upper area of the coop for some food, but last night sh couldn’t do it. She ended up hitting the roof and falling down! It was very sad, I even found her sleeping outside when I went to check on her! She must have been unable to make it to the upper area. I was wondering if this could be Marek’s. My other hen hasn’t shown any symptoms. Thanks so much!

  25. Hi there,
    This morning we lost our 3rd of our tiny flock (we initially had 5) to Mareks.
    We thought we were in the clear after we went 2 months without incident, but our sweet baby girl developed the symptoms and succumbed rapidly.
    I am concerned for our two survivors. Is there a time period where we can breathe a bit or will it always be a possibility that we will lose them? (They are nearly 30 weeks) Like you all, we love our girls, they are more like feathered puppies than what someone would expect a chicken to be… the waiting game is awful 🙁
    Thanks for your time,

  26. Hi what the best thing to do with a chicken house that’s had chickens with Mareks disease in it? I have culled the old flock and want to try no start a new healthy flock, is it advisable to use the same house?

    1. Hi Pete,
      No you shouldn’t use the same coop or even the same area of land. The disease can last for a long time after the hens have died.
      Getting a new coop and place it in a new place is the safest bet.

  27. Our local vet that sees Chickens threatened to call the CDC and have our entire flock killed if she found that one of them had Marek’s disease. So I am terrified to take my birds in to the vet now. I can’t bear to have them all killed if she finds Mareks. For a disease that is “everywhere” how can the CDC just go around murdering people’s pets??? They can’t possibly hope to eradicate the disease if it’s everywhere and stays in the soil for years. So what do they gain by this? Terrorism over the people? All it did was make me not want to take my birds to the vet.

  28. Hello,
    I grew up on a farm with lots of chickens and was excited to start a flock with my boyfriend as he had never experienced the joy of raising birds. We had a variety of 12 beautiful girls and in less than a year all had died but one. I did not have testing done to confirm, but I did take one to the vet and she suspected mareks. We had thought this was the case as the symptoms matched.
    I am now left with one lonely girl who we have not had the heart to cull. Anyway, my reason for writing is….
    We are moving! To a new property in a new town! And very much hoping to try again. Our current landlords ( on the Mareks site) want us to get rid of the coop. This is fine, but as we spent lots of money and time on it, I would prefer not to dispose of it if we don’t have to. Is there a way that I can clean it to make it safe to bring to the new property without bringing the disease with us?
    And if I were to keep my last girl in her own area in a different place from the others would it be too dangerous? I would appreciate any and all thoughts on these matters!
    Thank you!

  29. I have a small flock of chickens of two different ages. in one coop i have three laying hens. In the second coop I have four 18 week old chickens and a silkie rooster of about a year old.
    I noticed today that one of my chicks are experiencing symptoms of Meraks! I have separated it from the rest of the chickens but am curious as to what my next few steps should be. Should I separate my two coops further away from each other or is it too late at this point.
    In addition, How long should i keep the chick separated from the flock? is it likely it will pass away? Thank you for your help.

    1. Hi Micah,
      First step is you need to check if the chick actually has Marek’s. Your vet will advise you after this,

  30. I have 7 week old chicks that seem to be slowly succumbing to marek’s disease. I started with 15 and have lost a a chick a week or so down to 8 chicks as of this am. however this afternoon, two are laying on the floor with leg paralysis and cannot move, very mild weather, and fresh water daily. Not sure what to do or how to stop it from taking them all down

  31. Thank you so much for this article. It has taken away some guilty feelings. We lost 5 of 6 hens to this insidious disease despite taking all the precautions.

  32. I have a 1.5 year old Rhode Island Red hen that started to not seem like herself about 3 weeks ago. I isolated her from the other hens as soon as I found her in this condition. In the beginning, one of her eyes was closed most of the time and she was having trouble standing on one of her legs, and then she couldn’t hold her head up straight. This went on for the first week and a half, then it seemed like she was getting better because she didn’t have the above previously mentioned symptoms as much anymore. Now she seem worse than before. Since Marek’s disease normally kills a chicken pretty quickly what could this be? Botulism maybe? None of my other 7 hens seem sick either. I am not sure what to do with her. Please help.

  33. I have a 4 day old chick that can’t keep it’s balance. It is very active and gets very upset when it lands on it’s back. It also keeps trying to scratch around it’s ears. Worth noting is I lost a chick yesterday. It was different. It was sick from the day we got it and it never recovered…finally just laying down and dying. It was horrible to see. But it had no energy and refused to eat or drink. This one tries to eat and drink until it falls down. Please help with some ideas!!

    1. Have you inspected the bottom of its feet? Sometimes we think its a disease but could be an infection or irritation at the bottom of their feet.

  34. Hi. We have Buff Orpingtons, 38 one and three years olds in one large coop. They are pastured daily or were until one of the two year olds showed signs of problems. I separated her when saw she didn’t go out one morning three weeks ago. I thought it was egg bound, did the Epsom soaks etc then realized its not the problem. She has one foot pointing inwards. Now starting to eat and drink on own. Seems healthy. Can I put her back with her flock? If its Mareks they’d all already be exposed to it anyway. She’s not laid any eggs since separated. Recommmendation appreciated. Thx!

    1. Your correct, you would have already had Mareks spread. I recommend putting her back in the flock and closely supervise.

      1. I have tried twice to let her pasture with her flock, but the rooster seems to know she isn’t right and appears to be trying to kill her. So, she is still separated, but I let her pasture so she can walk their yard fence and maybe be able to return to her flock one day. If roo is trying to kill her will he stop as she appears healthier to him? She seems fine now, but still no eggs. We had another BO suddenly die one day last week. All others seem fine.

  35. My guinea has been diagnosed with Marek disease, she lays with both legs sticking behind her.seems ok otherwise, the other 5 seem ok too. What am I supposed to think

  36. Help! I have tiny baby Bantams that need to be vaccinated for Mareks but are too tiny to actually inject. My vet says there is a vaccine that is given orally but I cant find it and my vet is on vacation. Can anyone point me toward it?

  37. Hello, great article. I hatched 7 out of 12 fertilized eggs, barnyard mixes. Three days ago one presented unable to stand, five weeks old. She never does one leg back and one leg front lays in her size, eats, drinks tries to stand. We do not see her deteriorating, we see the same if not slight improvement. We have separated her and giving extra TLC. I’m torn on what is human, cull or wait a bit?

    1. I would give it another week or two, see if there is agony or suffering, that may sway your decision quickly.

  38. Well, last night my last chook carked it. The first in the flock developed symptoms of paralysis about a month ago and took about a week to die. From there, more and more of them developed “drooping” wings. Having seen it a few times, I always quarantined the affected birds, but to no avail. Not sure what a common survival rate is, but for me it proved lethal to 100% of the birds. They have plenty of space outside (20m2 a bird) and clean indoor sleeping quarters. We won’t be getting new chickens as the soil will be infected and take years before the virus dies off. Reckon we may just go with rabbits on another block of land we own. Back to store-bought eggs, blegh.

  39. hello. my little welsummer has always been a weak chicken. over the last month and a half she has had episodes of shortness of breath, weight loss and now weakness and malcoordination of her legs. all the other chickens in the flock are well with no symptoms and now reading this thread I am worried for them. It has been over forty days she has been like this…..if the others are not affected is it likely they are ok?. she does not spend time with the others and sleeps separately at night. she is bright in herself and now that her breathing is good I’m not keen on culling her as her appetite is good.
    what are your thoughts please?

    1. If she is doing better after 40 days of quarantining her then she should be okay to put back with the others. If she is still showing signs of sickness after 40 days then it’s likely she probably won’t improve.

  40. All advice is appreciated. I have a small flock of ex commercial hens, all vaccinated against Marek’s as they were in a caged environment before me. I rehomed a cockerel some months ago from a back garden breeder who was going to cull him because he was blind. He was very poorly but after some vet treatment he really picked up. Later he deteriorated & was PTS in May, post mortem tests showed he was Mareks positive. While he was never integrated in to my flock, they ‘met’ a few times in the garden and were around one another. I’m worried sick my girls could have contracted the disease from the contact they had with him, if that would have been enough. Does this mean I now have a mareks positive flock?

    1. The only way to be sure is to watch for symptoms or bring them to get tested. I would not be worried about it quite yet until there are signs.

  41. Hello, I have 2 cockerels of my meat flock showing paralysis. I had one before that we processed with the others also showing paralysis. I am from romania, chickens are the offspring of my rooster and hens, not high growth commercial breeds, all chickens involved were/are normal sized. they started developing symptoms after being stressed by other bad cockerels in the flock. This type of paralysis happened also last year, 2 down. Inside they didnt show anything obvious, but ofc I am not a veterinarian. one of the two sick is not even eating anymore they will be put down on monday. Is it possible to be marek?

  42. Sadly, several of the chicks I purchased this year have succumbed to Mereks. I took one in for a necropsy to be sure. All my chicks were vaccinated except 3 legbar chicks, the first to succumb and die at about 4 months old. I separated this years birds from the older group once I discovered it, but all areas are infected I’m sure. (they also all free ranged together) I cleaned, bleached, etc everything I could, but they continue to die. I don’t know how to cull a bird, nor am I cut out to do it, so I have isolated them and watched them deteriorate which is heart breaking. Some have lasted a month, others a week, all with different symptoms. Will they all die, including last years birds? This years chicks are now 5-6 months. Even though we have acreage, my $20,000 custom coop is on a foundation and not movable. Help!

    1. You should have culled and purged. There are locals that will cull for you, reach out. What did you use to disinfect?

  43. We purchased a dozen chicks from a reputable hatchery that claimed they vaccinate for Mareks. Their ages were 4 to 7 weeks old. One chick died suddenly at 2 months, a second chicken died we are pretty sure of Mareks about a month to a month and a half ago, and now we have a third chicken having issues. We think it is Mareks due to dragging a foot and looking under her wings noticed dark scabs on the feather follicles of one wing. She is no longer dragging the foot and her stride is normal and she is very alert, her eyes are normal and she is eating just fine. Since both chickens were in with the other chickens Mareks is probably in their coop area. None of the other chickens seem affected yet. We separated both chickens when symptoms appeared. We assume it is Mareks since we can’t determine how she got scabs, but she is doing so well we can’t bring ourselves to cull her. We hate to keep her alone, but would she infect the others if we put her back in with them?

  44. I’ve got Marek’s disease in my flock. I’ve had a vet confirm this. My question is, my guineas seem unaffected by this. Is is possible that all 60 guineas have it and aren’t showing symptoms? They’ve been exposed for at least 2 months. I also have two peacocks that are penned up and do not free range or roost with chickens. Do I need to cull them both 2? I’m looking at culling 20 buff Orpingtons, 60 guineas, and 2 peacocks. I’m devastated! Any advice would be great. I’ve been getting mixed messages on if guinea fowl and peacocks can have it.

  45. I am certain my coop has Marek’s and I have chicks being born. What do I get to vaccinate and can it be done orally?

  46. My rooster is 10 weeks old and and has started displaying some odd symptoms. He is wobbly on his feet and looses his balance (he looks drunk). When he lays down he spreads one foot out to the side and occasionally lays on his side (it looks like he is dead). I’m not sure if this could be Mareks. He is eating and drinking and still walks around the pen. Otherwise, he still looks perky. I have quarantined him away from the other birds as the other rooster was picking on him. He was incubated on my property and raised with 10 other chicks. I kept three of them (2 Roos and 1 Hen) and they have been living in the brooder box together. I have 5 other hens and they were raised from the incubator as well. None of the other chickens are showing any abnormal signs. Do you think this could be Mareks? How fast acting is this disease?

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  48. In January I brought home five chicks for my flock. I purchased from a local, organic farmer who has it turns out does not vaccinate from Marek‘s. All my existing flock has come from this farm. Usually as either fertilized eggs, or young chicks. One of the new chick died of confirmed Mareks a week and a half ago. Because I have a small flock of nine hens and a lot of space and keep it very clean, it wasn’t on my radar. My question is do I need to cull the remaining four chicks? They are 10 to 11 weeks old and exhibit no symptoms, but were definitely exposed to the other girl. My existing birds are between 10 months and three years, all healthy and laying. Thank you 😔

  49. Hi there,

    We have 5 chickens who are almost 3 months old. One of them is showing clear signs of Mareks (paralysed wing and diarrhoea), which the vet also feels is the case, and another is potentially starting to show similar signs. We’ll keep an eye on these and decide what to do. The other 3 chickens look and seem healthy at the moment. Our neighbour also has older chickens, who are situated about 5-10 metres away with a hedge and chicken wire separating them.

    The two questions we have are:

    1) How far can Marek’s spread on the dander? I assume it could travel the 5-10 metres in the wind and spread the disease?

    2) Given the chicks have been together from birth, we are assuming it has spread to the other chickens already. Is there any point in separating the chickens showing signs of Mareks from the others now?


  50. I have just had a hen put down with similar symptoms. She seemed to become ill very suddenly, and rapidly deteriorated over 3 days. Exactly the same happened with a young cockerel in the spring, deteriorating to unable to walk, stand, hold his head, or peck the food in the right place.
    Having read several articles about Mareks Disease I am convinced that this is it, even though this hen is 2 .5 years old. She has had feather issues for a year despite many and various treatments, and losing weight. She fits the Mareks symptoms list : (
    Sadly, the others must be carrying it too.

  51. Can you tell me your thoughts about the following — I would like to invite my friends and their kids over. They will be within 10 feet of my chickens and will walk on dirt where my chickens free range. About 3 weeks ago, they lost their entire flock to Mareks. Would I be putting my chickens at risk to have them over? They would make sure they clean all their clothes and shoes before.

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