Marek's Virus- The Most Frequently asked Questions

By seminolewind · Mar 12, 2013 · Updated Mar 13, 2013 · ·
  1. seminolewind
    Describe 'Marek's Virus- The Most Frequently asked Questions' here


    Q: Isn't Marek's Virus ONLY a problem for Big commercial operations?

    No. While the large commercial chicken operations got Marek's under control, Marek's was increasingly affecting the small flock owners' chickens.

    Q: How did this happen?

    Commercial chicken raising companies had to change their methods because they were losing so many chickens. They began practicing vaccination, " All In/All Out" with their flocks, and scrubbed and disinfected between batches of growers. Meanwhile, small flock owners like us were continuously adding chickens from everywhere, not vaccinating, and selling chickens that we didn't know carried Marek's virus, thinking that we would certainly never have that problem. In the 1980's , commercial chicken operations went from losses of 60% down to 5-10% nowadays. Meanwhile, Marek's is growing to epidemic proportions in the smaller flocks that we have. Most of us do not even know all the symptoms of Marek's in their chickens because it can mimic so many different illnesses.

    Q: What are the symptoms?

    Since now there are more strains of Marek's Virus, there are more symptoms. A chicken could have all , some, or no symptoms at all. Most of us know the classic symptoms, but we do not recognize all the many symptoms that Marek's can have.

    - The symptoms may include: paralysis of leg or legs, may have one point forward one backward OR not.
    - Cloudy eye, gray eye, or pupil not perfectly round, OR not.
    -They may have small tumors all over the outer skin.
    Wasting: Appearing to eat but not able to aim and pick up food, or not absorbing the nutrients and calories. Not looking sick until the end

    - Paralysis of ANY nerves in the body including nerves to the lungs (causing gasping), crop ,or digestive system not moving food along, (looks like impacted crop. OR not).
    - Paralysis of the legs is the easiest to recognize.
    - Small tumor lumps all over the body, or not.
    - Loss of control of their neck, and can't aim at food and pick it up.
    - Wing paralysis, or walking with their wings, or not.
    - They can look like there is nothing wrong with them with or without symptoms.
    - They may have some symptoms, or, symptoms that seem to come and go. . It may be months before death.
    - A necropsy can show tumors on organs. Some appear to just drop dead. It may be because they are wasting (starving) and the weight loss is covered by feathers, so it's not
    seen until the last few days before they die.
    *I know that's alot to read , please read it several times.

    Q:How do my chickens get it?

    A chicken Has to be exposed to a chicken that has it . Once they have, it's on your property, It will be there for years, or many years. There's nothing you can do. It's spread by chicken dust, dander, and saliva. You can't clean it away or cull it away. Keep a flock history. The information may help you decide when or if your flock was exposed.

    Q: When will my chickens first show symptoms?

    Most commonly you will see the symptoms at 6-12 weeks. However with new strains and mutation, Marek's affects chickens at any time of thier life. Most of my adults have been under 8 months old when they developed symptoms. A few were older. With older chickens, they usually waste. Chicks usually display paralysis. But this is not a rule set in stone. A Botulism paralysis usually kills a chicken within a few days. They will most likely look sick. Marek's paralysis usually does not cause death right away. Your chicken most likely not look sick at all.

    Q: How do I Prevent Marek's in my flock?

    You keep a closed flock. You need to start your flock by attaining day old hatchery chicks or hatching any eggs yourself. Never adding chickens that came from any other place. Not attracting wild birds. The guy at the feed store most likely does not know if they are vaccinated, but tell you that they are. Many older chickens have built up resistance, but can still carry it and infect others. Your flock may have it with no symptoms, yet, give it to unvaccinated chicks and they will die. Mareks' has no cure.

    Q: Can the Vaccine or vaccinated chickens give my flock Marek's?

    NOT from the VACCINE. A vaccinated chick or chicken can still be exposed to Marek's and spread it. The vaccinated chicken will have a 90-100% chance of not dying from Marek's symptoms even while carrying it.

    Q: Is there life after Marek's?

    Yes. Keep the flock you have.
    You can buy vaccinated day old hatchery chicks, and keep them quarantined for 2+ weeks. The longer the better.
    You can hatch your own flock's eggs. They may be resistant already. (I've done this twice).
    You can buy fertile eggs from others , incubate them, vaccinate them day 1, and quarantine them for 2+ weeks.
    You should not sell chickens from your flock. You can sell eggs. And if your chicks remain in strict quarantine, you can sell them. Remember that Marek's can be carried on you, your clothes, and your hair, and that will expose the chicks.
    Please practice a moral responsibility , and not give your exposed chickens to others. Most owners who have deaths from Mareks have cried for days and lost their favorite pets or the chickens they love. And there is nothing anyone can do to save them once they are exposed and develop symptoms.

    My first victim, MushMouse. The vet diagnosed him with Eastern Equine Encephalitis because he could not see any tumors in his necropsy. I didn't realize it was Marek's until over a year later when eight 6 week old chicks got paralysis one by one.


    My last Victim, Clarence. I had noticed he pupil was not round one day. He wasted away over a few months.

    most information supplied by
    "Diseases of Poultry" , 11th edition, Editor in Chief- Y.M. Saif

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  1. Echobabe
    I've been treating a broken leg for the last 2 weeks and have now come to believe the hen has Marek's (the 'limp' that caused her to break her leg in the first place). The break healed and I thought we were mending nicely, but her depression has worsened, I haven't been able to get her eating good again (so tube feeding as a supplement). Now she is is not eating and suddenly not able to balance on her good leg. I am devastated. Reading about the Marek's vaccine, it is considered a "leaky" vaccine (it doesn't stop the disease, only protects the host bird). From Wikipedia:

    "... because vaccination does not prevent infection with the virus, the Marek’s disease virus has evolved increased virulence and resistance to this vaccine.The first Marek’s disease vaccine was introduced in 1970. The disease would cause mild paralysis, with the only identifiable lesions being in neural tissue. Mortality of chickens infected with Marek’s disease was quite low. Decades after the first vaccine was introduced, current strains of Marek Virus cause lymphoma formation on throughout the chicken’s body and mortality rates have reached 100% in unvaccinated chickens.The Marek’s disease vaccine is a leaky vaccine, which means that only the symptoms of the disease are prevented.[10] Infection of the host and the transmission of the virus are not inhibited by the vaccine. This contrasts with most other vaccines, where infection of the host is prevented. Under normal conditions, highly virulent strains of the virus are not selected. A highly virulent strain would kill the host before the virus would have an opportunity to transmit to other potential hosts and replicate. Thus, less virulent strains are selected. These strains are virulent enough to induce symptoms but not enough to kill the host, allowing further transmission. However, the leaky vaccine changes this evolutionary pressure and permits the evolution of highly virulent strains.[11] The vaccine’s inability to prevent infection and transmission allows the spread of highly virulent strains among vaccinated chickens. The fitness of the more virulent strains are increased by the vaccine.

    The evolution of Marek’s disease due to vaccination has had a profound effect on the poultry industry. All chickens across the globe are now vaccinated against Marek’s disease. Highly virulent strains have been selected to the point that any chicken that is unvaccinated will die if infected. Other leaky vaccines are commonly used in agriculture. One vaccine in particular is the vaccine for avian influenza. Leaky vaccine use for avian influenza can select for virulent strains which could potentially be transmitted to humans.[12]"

    So why isn't the poultry industry DEMANDING a better vaccine? It seems to me we are creating a monstrous disease with implications against human health as well. I love my birds, and I am getting really tired of trying to be a good chicken mom and seeing these sweet birds suffer from industry induced problems :(
      shannon84 likes this.
  2. seminolewind
    Hi, I have a website for you but this forum won't let me paste the website. Email me at [email protected] and I'll send it to your email
  3. seminolewind
    Hi. A lot of us here get chicks in the mail from hatcheries that are 48hours old and vaccinated. Do you have chick hatcheries to order from there? They might also carry the vaccine for sale. If not do they sell vaccinated chicks? If you order vaccine, it has to be shipped on ice packs. Let me ask Casportpony if she has any information on WA.
  4. Snow bunny
    seminolewind (Karen), thank you for kind words and advice. Yes, my girls were very special to me as well, they helped with my depression and anxiety and I loved them to bits. I had Sussex Light, Buffs, Australorps and my most favourite was my Naked Necks. I didn't know that you can vaccinate them yourself, there is nowhere in the part of West Australia that I live that will help with chooks, and I am not big enough for a Country Vet to call. My local vet will not vaccinate chooks, nor will they do anything for aviary birds. So it is down to anyone who keeps chooks to do things themselves. WA is just too vast and if you live rurally, there is no hope. What is the vaccine that you use please? I will see if I can get it over here. As gutted as I am. I will take your advice and not give up. I just loved my girls so much and it took so much time to set it all up and get my girls. I'm pleased that I am not the only one to cry over chooks. I would be called a wus here. So, thank you for writing to me. I didn't know raccoons killed chooks, that is a new one for me.
      shannon84 likes this.
  5. seminolewind
    Snow bunny , so sorry. The virus is nasty and all the good things you do don't make it go away. I was devastated as well. But I wanted chickens so now I get them vaccinated forMarek's at the hatchery or doing it myself at day one of life. Then keeping them quarantined for 3-6 weeks. So now most of my flock is vaccinated and doing well. I have 10 non vaccinated older birds, and 28 vaccinated. The 10 are older chickens that are resistant.
    Don't give up. You may need some time, but chickens are wonderful and you can have them. I know what it's like to lose them to Marek's. I cry for days with some. My last 4 were killed by a raccoon and it's been a few months and I can't even think about it and have a good cry. 2 were the most special chickens I had.
    I'm very sorry you got to experience it like so many others here.
    I've moved to a different chicken site. So I only come here to answer questions to me. I get a notification .
  6. Snow bunny
    I introduced a rooster to my girls after getting him from a selling site. Now I have lost my girls one by one and only had the rooster left. I unwittingly bought the virus in through the rooster. This rooster has now been culled. So even though I kept my girls coop clean, gave them good food, clean water twice a day and clean bedding every day, I still lost them. It is so sad when you lose them and now, I have closed my coops down as I cannot go through that again.
  7. seminolewind
    I've recently lost 2 hens, one at 1 year old, one at 18 years old. No paralysis just wasting. The first was diagnosed by a state lab.
    Chicken girl, no, not true.
  8. CarolyneT
    I lost 60% of my flock of unvaccinated Bantams to Mareks 4 girls and both boys; just as the deaths stopped my vaccinated hens started to die, again 60% loss. Some paralysed, some wasted away and others just dropped dead with no symptoms. New strains of Mareks are totally resistant to the vaccine, it is a hideous disease!
  9. ChickenGirl2010
    My friend keeps insisting that if you get them vaccinated for marek's they die younger is this true?
  10. mithious
    Thank you sooo much for this information! Highly valuable! I have a closed flock and do practice biosecurity, but now will be even more careful! I am so very grateful to all of you who, through your pain, are still willing to teach us! God Bless, you are in my prayers always!!
  11. Chickenfan4life
    Well done, and so helpful! Thanks!
  12. willowbranchfarm
    Great job!!!! Very informative. :)

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