NEW 8/8/15
Here is new information - August 2015 that makes a case to NOT vaccinate for Marek's

Gail Damerow spends a couple of pages on this in her book: the Chicken Health Handbook
"..............Chicks hatched from survivors of disease exposure are particularly hearty and may carry maternal antibodies that give them further immunity." p12

Here's another valuable quote from the same book (can you tell I like Gail Damerow's books for their thoroughness and easy referenceability?)

"When only certain strains or individuals are resistant to a disease immunity is 'partial.' Chickens have partial immunity to Marek's disease, since some strains never succumb to the otherwise common killer. In nearly every disease outbreak, some individuals do not become infected due to inherited immunity. Those are the birds you'll want in your breeder flock if you wish to breed for resistance, as described in chapter 1." p198

note: I have added the emphasis in the above quote.

really good article from the Poultry Club of Great Britain...and link to their health site - copied here for easy reference:

Remember too, different strains of Marek's exist in different countries.....

Here is another good thread with insights to Marek's

For all BYC members, please use this page to update your fellow members on information that you have gained about Marek's. Please cite the source for the facts that you post and put in links. Useful information for members facing this/learning about this would be things such as:

Please put in quotes and links to:
University Bulletins
Professional Publications
Costs of Necropsy and how to get one done etc.

Thanks in advance for your Help and contributions and your management techniques and opinions. Please be very respectful to your fellow BYC posters.

I Marek's Disease Links and Information
II Necropsy links and information
III Approaches to Managing Marek's in your flock
IV Ideas for others to consider
V Symptoms that your chickens displayed with Marek's

I Marek's Disease Links:

The Poultry Site:

Excellent synopsis/overview:

Merck Vet Manual:

Detailed information and photographs of affected chickens:'s


Encyclopedic article:'s_disease

From the above article: Prevention (Emphasis in Red is mine)

Vaccination is the only known method to prevent the development of tumors when chickens are infected with the virus. However, administration of vaccines does not prevent transmission of the virus, i.e., the vaccine is non-sterilizing.[1] However, it does reduce the amount of virus shed in the dander and hence reduce horizontal spread of the disease. Marek's Disease does not spread vertically. The vaccine was introduced in 1970 and the scientist credited with its development is Dr. Benjamin Roy Burmester.[5] Before that, Marek's disease caused substantial revenue loss in the poultry industries of the United States and the United Kingdom. The vaccine can be administered to one day old chicks through sub-cutaneous inoculation or by in-ovo vaccination when the eggs are transferred from the incubator to the hatcher. In-ovo vaccination is the preferred method, as it does not require handling of the chicks and can be done rapidly by automated methods. Immunity develops within two weeks.[2]
The vaccine originally contained the antigenically similar turkey herpesvirus, which is serotype 3 of MDV.[6] However, because vaccination does not prevent infection with the virus,[7] the Marek's Disease virus has evolved increased virulence and resistance to this vaccine. As a result, current vaccines use a combination of vaccines consisting of HVT and gallid herpesvirus type 3 or an attenuated MDV strain, CVI988-Rispens (ATCvet code: QI01AD03).[8]

University of New Hampshire / University of Connecticut :

Concise important information:

From Diagnosis in the above article:"Diagnosis is derived from the flock history, symptoms and necropsy findings."

Shagbark Bantams has this article by K.J. Theodore:

Summary of the diesease and insights:

Of note is that the disease is so common that it is in every flock and that keeping chicks away from adults until the chicks have passed 5-months of age is useful information. Ususal appearance between 5 and 25 weeks of age. Here is a quote from the above article:

" There are certain 'B factors' contained in the blood of some chickens that make them resistant to Mareks. If you have access to a lab for 'B type' blood testing, 'B factor' birds are desirable for breeding for a 'Mareks-free' flock.

Overall, the easiest way by keep Mareks out of your flock (but not the most effective), is to promote 'age resistance' by keeping your youngsters separate from the adults and away from the poultry shows until they're over 5 months old.

First State Vet Supply Article by Peter J. Brown:

Insight to Mareks Disease Virus:

Of note - not from article: It has been said that the use of 1/2 the wafer is less effective than mixing the entirety eventhough there will be wastage for those with fewer than 1000 vaccinations to make. The mixed vaccine is only viable for 1/2 hour. (Unless the article has been revised since linking). The reason for this is that the virus may not be equally distributed in the disolvable wafer.

Freezing and thawing can kill the Marek's virus. Here is a quote from the above article by Peter J. Brown:

"Mareks vaccine is unique in that it does not stop a bird from becoming infected with the virus,but it stops the formation of the Tumors that are caused by the Mareks virus. Birds that are newly vaccinated should not be exposed to adult birds for at least fourteen days to allow the vaccine to take hold."

Purdue University:

Excellent and informative article that includes a table that compares Marek's to Lymphoid Leucosis:

Miller Hatcheries Article:

Consice overview:

Quote from the above article: "The first indication of the disease is a variation in the growth rate and degree of feathering."

From Tasmania Animal Health and Welfare Branch--- (cheers for the Southern Hemisphere): 'Marek's Disease Fact site' here

Mississippi State University Extension:'s.pdf

Of huge interest is this quote from the above link: "Acute Marek's disease can be extremely rapid in its course, producing mortality in
apparently healthy birds. However, in some cases the lesions may regress and clinically
affected birds may make complete recoveries." --- Did I hear that correctly? Complete recoveries?

(add more links and articles here)

Really informative!-- (~AmberRex~)
II Necropsy Information - contacts and costs

Texas A&M

A gross necropsy does not include the cellular level cultures. For my pullet, they did not discover the Marek's at the gross necropsy level. For this reason they needed to do cellular level cultures. This is more expensive, takes longer and is more conclusive

This is a cut and paste by Ridgerunner and madamwlf from a BYC post on Marek's
Quote: Originally Posted by madamwlf

I've lost 7 birds to the very disease they were vaccinated for: Mareks. And it would have cost me $100 to have further tests done. They all had classic Mareks symptoms. None of my other birds have become sick at all. I believe something happened with their vaccine. Anyway, to the OP I'm sorry to hear about your bird.

I searched for Maryland fees for Necropsy. The fee list I found was dated 2006, so it may be out of date, but it said avian pets cost $200 with carcass disposal fees additional, a small charge per pound. With poultry, that would be negligible. Farm poultry was No Charge for the necropsy.

In Arkansas, the cost was $45 for the poultry necropsy with a $15 carcass disposal fee. I'd heard it was only $10 but that's not what I found when I looked it up. This fee list was dated 2008, so maybe it has been reduced, but I don't think so.

The cost can vary widely from state to state and it can depend on how the bird is classified. You might discuss with them how they are classifying your chickens.

ChicKat, when you build your fact page, you might comment on both the widely varying costs for necropsy per state and to be careful how your bird is classified. Just a thought..

(add more links and Necropsy information here)

III Approaches to Managing Marek's in your flock

Chickat: Currently I have 6 chicks from a hatch May 25th of 2012. I have decided NOT to vaccinate them. I am trying to raise Marek's resistant chickens. These chicks were hatched here from eggs from my Easter Egger who was in the pen, and on the perch with the pullet that I lost to Marek's. So their mother has some resistance. I am going to try to continue that resistance in her chicks.

NYReds :My approach to Marek's is the same as my approach to all other poultry diseases except Coccidiosis. I do not vaccinate or medicate for anything, again, except for Coccidiosis.
I immediately cull, which in this instance means kill, any bird that shows signs of illness. I have followed this practice for years & rarely heve any illness in a line of birds I've bred for more than 5 years.
Occasionally I am attracted to something new [actually more than occasionally-I like them all] and I have to repeat the process with the new birds but it always works.
To me it makes more sense to reproduce birds that are healthy & don't require medication than it does to reproduce birds that are prone to illness. In most cases these birds will produce offspring that are also prone to illness.
I wish I could claim ownership of this "breed for resistance" concept but I'm not that smart. I have to credit F. P. ]Fred] Jeffrey's booklet CHICKEN DISEASES which is published by & I think still available from the American Bantam Association.

(add your approach here)

IV Ideas for Others to Consider
On BYC member Nambroth has posted lots of information regarding Mareks and gave me permission to link to their BYC page here:
( add more ideas here)

V Symptoms that your chicken(s) Displayed

Chickat: First symptom drooping wing, with in 24hours semi paralysis of the other wing. With in about 55 hours at the medical lab in the pet carrier the one-leg-forward, one-leg-back symptom.

Symptoms (seminolewind) from Diseases of Poultry, chief editor W.M. Saif, pgs 407-446: My chickens displayed some of these but not all.

"Marek's disease may show signs, but few are specific to Marek's alone.
In nerve dysfunction- , Paralysis syndrome or peripheral nerve disfunction, may be progressive, and involve more than just legs and wings. Some nerves affected with MD include show crop paralysis or dilation , or gasping (vagus nerve). Incoordinate gait. One easily spotted symptom is one leg forward one leg back from unilateral paralysis. Transient paralysis of the neck.

Chickens with MD lymphomas have fewer signs, may become depressed or comatose prior to death, They may appear clinically normal. Nonspecific signs can include weight loss (wasting), paleness, anorexia, diarrhea. Deaths can be related to starvation and dehydration caused by MD lymphoma. Nervous tics or torticolis.

There is Early Mortality syndrome, which is especially virulent strains related, can cause death within 6-8 days. There is also a Latent Marek's syndrom, where the chicken is older than commonly noted.
Chickens can have transient paralysis, they get better, but die from MD at some point.
Sometimes vaccinated flocks can have significant outbreaks that seem to flair up, then abate.
Skin tumors that are found at the hair follicle.
Marek's exposed chickens are most susceptable to opportunistic bacteria, like coccidiosis, eye infections. etc. "

Factors that influence mortality and lesions: virus strain, dose and route, gender, maternal antibodies, genetics and age, prior infections, environment and stress.

Ocular-gray or cloudy eye, mis shaped pupil, or recognition of blindness in bird. Can be one or both eyes.

My Chickens:

Paralysis , cloudy eye, crop stasis, gasping, wing paralysis, no neck control, a pupil that changed shape, wasting (mostly), pecking but not really eating food, most of these birds looked happy right up to the end. I've had an 8 week old with paralysis that got better after 2 months and went back to the flock a few months ago. I've had youngsters die from coccidiosis and eye infections from poor immune systems related to Marek's. I've had a 2 year old roo that had all the classic symptoms. I've recently had a roo that was over 2 years old have a change in pupil shape a month before he died. He was eating but wasting. Most of my demises have been chickens under 8 months old. But about 5 that were older. I've had batches of chicks hatch that were not affected, yet one hatch last year took all 7 chicks at 8-16 weeks old. (Seminolewind)

12/24/2013 In the past several months, I've lost 4 birds. 2 were vaccinated, 2 were from "resistant" parentage. I cannot understand that 2 out of a batch of 5 suffered wasting and actual paralysis at 18 months old. Maybe it was my error in using the vaccine, or maybe the vaccine got warm. I don't know. Then 2 roos hatched from my eggs and brooded by a silkie got paralysis and wasting about a month apart and they were 8 months old. I have one more who's about 4 months. I'll have to wait and see.

I'm not so sure about my eggs hatched by my chickens. I had a batch of Jersey Giants that were from resistant parentage and incubated in the house and they are doing okay. My last 8 to die from Marek's had all spent all or some time living in this shed that is coop in one half. I've sprayed and sprayed. I have now closed it down and will not keep chickens in there. What I'm trying now is pens , protected from rain and predators. Just open air. The breeze comes generally from a non chicken direction. Maybe it will make a difference. I live in Florida and can keep the birds that way.
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