The Great Big Giant Marek's Disease FAQ PAGE 2
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CONTROL
How is Marek's spread?
Marek's virus is spread by several different vectors. The virus is an encapsulating virus, meaning it creates a protective shell around itself after it leaves a host. Because of this, it can survive outside of a host for a long time! Think of it as a tiny, awful seed that holds the virus inside, just waiting to be "planted" on a new chicken. It is important to remember that most commonly it rests in the dander (dust, feather particles, etc) of an infected chicken. Dander can be so fine that it's barely visible. Infected chickens that generate this dander may never show symptoms, so you might have no idea they are spreading the virus.
Dander can be spread via:
It is important to remember that the virus can live for months or even possibly years outside of a host.
Doesn't this mean that Marek's is EVERYWHERE?
Yes and no! Marek's IS common but it is not necessarily everywhere. There is hardly any “guarantee” that any given flock or chicken will become exposed to Marek's. I have heard some say that it is not a matter of “if” but “when”, which is a little misleading. Marek's is very common and is very easily spread but should not be considered “everywhere”. Despite it not being “everywhere”, it is still important to practice good bio-security and use caution! If you like, you can imagine it's everywhere and use that to inform your biosecurity, you will be much less likely to accidentally bring it home to your flock.
Can't I cull all my chickens, clean everything, and start over?
Maybe, but it is risky, very impractical, and unlikely to totally eradicate the virus. It is important to remember that Marek's travels on chicken dander, which can blow everywhere on your property. It can live for months or even years in the environment. Even if you culled all your birds and managed to 100% sterilize your coop, the means by which to remove it from the soil on your entire property (and possibly neighbor's, if you do not have a large lot) is financially beyond the means of most backyard keepers. It is also likely you have tracked it into your home at some point. And, even if you managed to do all this, there is the chance it might come back in on the wind or a bird (etc) anyhow.
In the end it is a personal choice, but the measures to eradicate it from home, backyard, and farm type environments are extreme and it is hard to do. Most keepers opt to vaccinate new birds and/or breed for resistance.
What if I build a new coop on the other end of my property?
This is unlikely to change anything. As noted before, Marek's spreads very easily on a breeze or on your shoes, clothes, hair, when a chicken flaps, on the dog's feet when he runs across the yard... etc. It would not be impossible to imagine many ways for the virus to make it from one end of a property to another, even if the property is many acres in size. Marek's is known to spread for miles quite easily. If your property is very large you can try this, but it might be a waste of time and resources.
How long can the Marek's virus "live" without a host, such as in the soil or surroundings?
It is complex to talk about viruses as living things (most scientists consider that viruses are not living things), so for the sake of this article when I say "live", I mean "intact and still able to infect a chicken" or remain infectious. Marek's virus has been shown to be very long-lived outside of a host, as many herpesviruses are. It has been documented to live for 65 weeks (that's over a year and a half!) with no host, in an uncleaned environment. Research seems to indicate that Marek's virus lives the longest in DRY environments, such as inside coops, homes, anywhere dust can accumulate, and also in more arid climates and drought stricken areas. It seems to break down more quickly in wetter environments, such as in the soil and in moist climates where it is exposed to the elements. There is also research that indicates that solar radiation (exposure to direct sunlight) can help break down the virus capsule over time. There are many factors at play that determine exactly how long the virus can live, so it is important to 'assume' that it will be there longer than you expect. While we can get things such as coops and non-porous surfaces clean with proper cleaners (see section as to what cleaners kills Marek's virus), it is impossible for most backyard chicken keepers to clean the soil and surrounding environment, and so it must be assumed that any place that an infected chicken has been also is laced with shed virus that can live for over a year and a half at a minimum. Though it has been documented to live for over a year and a half, there are those that think it can live for over 7 years in an uncleaned environment (such as indoors, in a coop, barns, etc). There are other factors that may come into play with how long virus might live; however it has been shown to survive even very hot summers and cold winters, so you cannot rely on your environment alone to negate it.
So it's nearly impossible to eradicate. Should I still clean things?
Yes! This is still a very good idea. In fact, other than keeping your chickens overall in good health, it might be the most important thing you do. Reducing the amount of virus in your chicken's environment can only help to prevent spreading it further either on the wind, on yourself, via wild animals, etc. It is best to concentrate on areas where chicken dander accumulates, such as inside of coops, barns, etc. physically remove as much as possible (I like to use a shop vac with a drywall filter) and then saturate surfaces with a virucide to kill the virus. If you use an earthen floor in your coop, consider replacing the top few inches. If you cannot do this, research the safe use of lime in the soil. You cannot hope to completely eliminate 100% of the virus, but you can significantly reduce the amount. The side benefit to this is that by keeping a cleaner environment for your surviving chickens, they will have less stress and chance of becoming sick from a secondary illness. Anything you can do to make your Marek's positive chickens healthy and stress-free will give them a stronger immune system.
My chickens have been vaccinated, but I have or have had Marek's in my flock. Will they still shed the virus?
Yes. Studies have shown that it does not make a difference if birds are vaccinated or not-- once exposed and infected, even if they never show symptoms, they shed the virus. There is no considerable difference in the amount of virus shed, between vaccinated and unvaccinated individuals, once they have been exposed. All birds exposed to Marek's virus should be considered carriers, for life. Reference: http://www.biomedcentral.com/1746-6148/7/70
Can I use bleach?
Bleach is not known to be effective against Herpesvirus (Marek's) on porous surfaces.
What kills Marek's virus?
You want a cleaner that has a known virucidal aqgent that kills Herpesvirus. Use as directed on the label as a virucide, and always use proper personal protection! These strong cleaners can be harmful to yourself, your birds, and the environment if misued, so always follow label driections carefully. Use personal protection and a mask or good ventillation. Don't expose your birds directly to these cleaners or their fumes when using them.
The following are listed to be killers of herpesvirus. There may be others, and it's worth researching:
Odoban http://www.odobanprofessional.com/products/odoban/odoban.php
Activated Oxine http://www.bio-cide.com/uploads/Efficacy Oxine.pdf - Note, it MUST be activated to kill Marek's!
Virkon S http://www.biosecuritycenter.org/content/labelClaim/virkonS.pdf - Specifically mentions that it can kill Marek's, and on porous surfaces. Probably the best choice for very serious situations.
Article: Disinfection of Marek's Disease Virus in Poultry Dust: http://www.tandfonline.com/doi/pdf/10.1080/03079457708418232 Note that this is an older article and while still useful, it is probably best to use one of the products listed above for home use.
If you know of other viable viruicudes that kill herpesvirus, feel free to share them.
How do I keep from spreading this virus to others?
It is very thoughtful to try to keep this virus from spreading.
-It is ideal dedicate a pair of shoes as 'chicken only' shoes that you wear when you do daily chicken chores or walk in the coop. It's actually best to do this even if you have no illness in your flock! It's a great step toward general biosecurity! Keep them seperate from your other shoes and have a designated "home" for them such as a boot tray. Clean them in a shoe wash or boot bath, etc, as often as you wish. Don't wear them off of your property. If you must do so, then completely sanitize them before you go, and after you return.
-When you plan to go to a place that other chicken keepers go, such as the feed store, consider washing or thoroughly spraying your shoes with one of the virucides listed above, before you go and after you get home.
-Don't give away, sell, or show any chickens from a flock that has had Marek's virus exposure.
-If other chicken keepers visit your property, offer them baggies for their shoes, and/or dip or thoroughly spray their shoes with a virucide before they walk where your chickens go, and again when they leave. Do the same for your shoes when visiting other chicken keepers property.
Can I show a chicken that has been exposed to Marek's disease?
This is putting other chickens at the show at risk, and could be considered irresponsible and unfair. If you plan on showing chickens, it may be important to confirm if you have Marek's disease in your show birds or not. Remember that some other diseases look like Marek's. A blood test might be worth your time and money if showing chickens is very important to you.
Can I breed and sell birds that have been exposed to Marek's disease?
Again, this is putting other chickens and chicken keepers at risk. If you wish to breed and sell birds, it might be worth your time and money to get a blood test run on your breeding birds to be sure if they have Marek's (or not). While they cannot transmit the disease vertically (through the egg), any hatched chicks would become exposed upon hatching. It is possible to hatch eggs in an incubator even if the flock is Marek's positive, but EXTREMELY good bio-security measures would need to be taken and the chicks would need to be raised in very careful biosecure ways to keep any trace of chicken dander away from them. It would require a great deal of effort and dedication to keep the chicks from becoming accidentally exposed until the point of sale. It can be done but it is not easy, so consider carefully if you feel you can truly commit to it.
It may also be possible to sell hatching eggs, if you exercise extreme caution about accidental exposure of the eggs or packing materials to the virus. It would also be ethical to let potential buyers know of the risk.
Can I give one of my Marek's exposed chickens to someone else that has Marek's?
This would be risky. There are now several strains of Marek's, some of which have mutated. There is a chance that the strain that your birds have is different than the one in someone else's flock. If this were the case, it could infect both your bird and theirs and cause a new flush of symptomatic birds. Especially if any of the birds already have compromised immune systems! Do this only if the risks are acceptable. It might only complicate the problem.
How can I prevent Marek's disease in my unexposed flock?
First: Educate yourself. The fact that you have made it this far gives you a head start!
Now that you have the information, you can decide if you want to vaccinate, or not. See: Vaccinations, above. There are benefits to vaccinating day-old chicks, and possible benefits to vaccinating older, unexposed birds.
Then, do everything you can to practice good bio-security.
If you visit other areas with chickens, consider washing your shoes, clothes, and even your body as soon as you get home. Unfortunately our hair can carry a lot of dust/dander. Think critically about where other chicken keepers frequent, such as the feed store. It is not over-doing it to do a shoe wash after getting back from the feed store. In fact, it's very good habit to have shoes you use only for your chicken keeping tasks. Read on about shoes!
Shoes are a big deal! It is ideal dedicate a pair of shoes as 'chicken only' shoes that you wear when you do daily chicken chores or walk in the coop. I use easily washable rubber boots. It's actually best to do this even if you have no illness in your flock! It's a great step toward general biosecurity! Keep them separate from your other shoes and have a designated "home" for them such as a boot tray. Clean them in a shoe wash or boot bath, etc, as often as you wish. Don't wear them off of your property. If you must do so, then completely sanitize them before you go, and after you return. Try not to walk in the areas your chickens use in the same shoes that you use to go other places, such as the feed store or a park. This will protect your birds from much more than just Marek's. Now that Bird Flu is becoming more of a problem, tracking things in on shoes should be strictly avoided.
Use a lot of caution when buying, adopting, or getting new chickens from swaps, fairs, markets, Craig's list, other keepers, etc! Don't be afraid to ask questions about their flock, any past illness, any deaths in the last few years? Trust your gut if you see any red flags, and always quarantine new birds for a minimum of 30 days (60-90 is best but might not be practical for most keepers). Quarantine is not a guarantee (remember, a bird can be infected and never show signs!) but it is better than nothing. Understand the risks! Most people that bring home Marek's do so by bringing home new, already exposed birds. Backyard Chickens forums are full of stories of people bringing home new birds and watching in dismay as over the period of a few months, diseases seem to "appear from nowhere". In reality, chickens can carry illness and seem perfectly healthy, then share them weeks or months later with your flock.
Finally, do everything you can to keep your birds healthy, clean, and stress-free. Stress weakens the immune system, which invites trouble. By keeping things clean and removing dander periodically, you reduce the amount of disease vectors in their environment. And, a healthy chicken is going to have the best immune system! A good diet and low stress life is core to long-term health.
RESOURCES
If you have chickens... even if they have never been sick, now is the best time to take some time and make yourself a list of contacts. This will save you a lot of headache in case something happens. Having the information already written down can really help you cope with a chicken medical situation!
Sit down and answer the following questions, making a list where applicable
Diagnostics and testing
LIST OF POULTRY DIAGNOSTIC LABS, BY STATE: http://www.metzerfarms.com/PoultryLabs.cfm
LIST OF POULTRY DIAGNOSTIC LABS, via forum: http://www.backyardchickens.com/threads/necropsy-and-disease-testing-lab-info.1236884/
Texas A&M Veterinary Medical Diagnostic laboratory - http://tvmdl.tamu.edu/tests_services/test_info.php?test=Marek's-Disease-(PCR)&unit_id=1187&unit_effdt=02-JUN-10
They offer PCR (genetic/DNA) testing of blood samples for Marek's markers. Blood can be drawn from a live chicken. You may need the assistance of a veterinarian or a vet tech for a proper blood draw and/or for a sample vial. Call for up-to-date fees and any special instructions.
University of Georgia, Poultry Sciences Extension - http://www.caes.uga.edu/applications/personnel/profile.cfm?ID=4315
They have done extensive PCR testing for me via blood sample and tissue samples after necropsy. You will need to contact them to find out how to submit samples and what their fees are.
UC Davis, Veterinary Medicine (California) -
http://www.cahfs.ucdavis.edu/services/lab_locations.cfm
www.vetmed.ucdavis.edu/vme/taqmanservice/FAQ.html
Offer necropsy services and qPCR testing. I am unclear if they will take out-of-state samples; calling them directly for inquiries is your best bet! This is an invaluable service for California residents.
Contact your state's agricultural / extension offices to inquire if they preform testing. As PCR testing continues to improve with technology and up to date sciences, more and more labs offer these diagnostics. It's worth asking. If not, they should be able to point you in the right direction toward someone that does. This information is great to have on hand before you have any problems.
Poultry/Extension Labratories, by state:
http://www.aphis.usda.gov/animal_health/nahln/downloads/all_nahln_lab_list.pdf
List of State Veterinarians:
http://agr.wa.gov/FoodAnimal/AnimalHealth/statevets.aspx
Find a local avian vet. http://www.aav.org/search/index.php
This may not be possible in some areas, and not all avian vets see chickens regularly, but if you have this resource, it can be invaluable! My own vet has helped me more than I can ever say.
How to send a dead bird for necropsy, with photos: https://www.backyardchickens.com/threads/how-to-send-a-bird-for-a-necropsy-pictures.799747/
Experts in Poultry / Avian Medicine
Dr. Jarra Jange at Cornell University of Veterinary Medicine (Ithaca, NY) - http://www.vet.cornell.edu/popmed/bios/jagne.cfm
Dr. Jange is very knowledgeable about poultry and specializes in Field investigation of common diseases of poultry.
The Experts at UC Davis (California, multiple locations) - http://www.cahfs.ucdavis.edu/services/lab_locations.cfm
University of Georgia, Poultry Sciences Extension (Athens, GA) -http://www.caes.uga.edu/applications/personnel/profile.cfm?ID=4315
List of veterinarians, as compiled by BYC users, that will see poultry (not necessarily "experts") - https://www.backyardchickens.com/t/200108/list-of-vets
Note that not all of these veterinarians can be considered "experts" in avian biology. It is always a good idea to ask questions and find out how experienced a vet is about poultry medicine. In a pinch, though, sometimes any vet is better than nothing. Use your best judgement. If a vet is experienced with Marek's disease, all the better. The information about this disease has evolved and continues to do so.
Vaccines
See “Vaccinations” section.
Necropsy Tools
These can aid you if you are preforming a necropsy at home. Warning: Graphic photos!
Cornell University / College of Veterinary Medicine: http://partnersah.vet.cornell.edu/avian-atlas/search/disease/502
Take special note of the different tabs above the photos. Clinical signs are outward symptoms. Gross lesions are photos of what you can expect to find inside the bird. Normals are photos of what normal, healthy organs look like, for comparison.
University of Minnesota Veterinary Dignostic Library: http://www.vdl.umn.edu/prod/groups/cvm/@pub/@cvm/@vdl/documents/asset/cvm_asset_350829.pdf
This file contains a section on Marek's disease, as well as photographs of lymphomas.
Articles, papers, more reading
It is important to note that most scientific research conducted on Marek's disease has been conducted on large scale farming operations, typically of meat birds and production layers. Studies are very expensive and usually only commercial operations pay for them. Not on small backyard flocks, small flocks that are able to range in uncontrolled outdoor conditions, or pet chickens. Because of this, many such articles that are targeting commercial operations suggest culling all infected birds. This is because in industrial applications, the entire area where chickens live (indoors) can be treated with virucides and the virus can be completely killed off, which we cannot do in our yards. Some of the research is also out of date with the current types of vaccines used by some hatcheries and some of the mutated strains of Marek's. Use your best judgment when taking advice from this article or any other article you read. Check the dates on the articles. Don't feel alone-- many of us have been on the same frustrating and confusing journey that you are embarking upon!
The Poultry Site: http://www.thepoultrysite.com/diseaseinfo/90/mareks-disease
Mereck Vetrinary Manual: http://www.merckmanuals.com/vet/poultry/neoplasms/mareks_disease_in_poultry.html?qt=&sc=&alt=
Purdue University: https://www.addl.purdue.edu/newsletters/2005/spring/mareks.htm
World Organization for Animal Health: http://www.oie.int/fileadmin/Home/eng/Health_standards/tahm/2.03.13_MAREK_DIS.pdf
Bird Health: http://birdhealth.com.au/flockbirds/poultry/diseases/mareks_disease.html
Vaccinal Control of Marek's Disease: http://www.sciencedirect.com/science/article/pii/S0165242706000912
Various Articles by the American Association of Avian Pathologists: http://www.jstor.org/stable/i23526266
Professor Schat's Writings on Marek's disease: http://en.engormix.com/mbr-42868/karel-schat
Replication Kenetics of Marek's Disease: http://vir.sgmjournals.org/content/86/11/2989.long
ARS article on new PCR testing for Marek's as well as the development of new vaccine (August 2014): http://www.ars.usda.gov/is/AR/archive/aug14/disease0814.htm
Seminolewind's FAQ: https://www.backyardchickens.com/a/mareks-virus-the-most-frequently-asked-questions
Marek's Fact Page: https://www.backyardchickens.com/a/mareks-disease-fact-site
Bird Health Marek's page: http://www.birdhealth.com.au/mareks-disease
"How to send a bird for necropsy" with photos (forum thread): https://www.backyardchickens.com/threads/how-to-send-a-bird-for-a-necropsy-pictures.799747/
COMMUNITY
Online and offline communities can help you manage and deal with having a serious illness in your flock, via sharing information, and offering hugs through this difficult process. You can search us out or start a new thread here:
https://www.backyardchickens.com/f/10/emergencies-diseases-injuries-and-cures
There are now more resources online than ever before... if you find yourself wanting to research more deeply, go for it. Edit for 2025: Do be aware that AI generated results can be misleading, have false information, or incomplete information. Do not rely upon them. Make sure to cross reference and seek out full information form human-written papers, articles, and more. Be careful out there.
End Note:
I release this article under CC BY-NC-SA 4.0 which means: You may share and adapt this article, as long as it is with attribution, is non-commercial in nature, and is ShareAlike (your adaptation must have the same creative commons license). Full information: https://creativecommons.org/licenses/by-nc-sa/4.0/
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CONTROL
How is Marek's spread?
Marek's virus is spread by several different vectors. The virus is an encapsulating virus, meaning it creates a protective shell around itself after it leaves a host. Because of this, it can survive outside of a host for a long time! Think of it as a tiny, awful seed that holds the virus inside, just waiting to be "planted" on a new chicken. It is important to remember that most commonly it rests in the dander (dust, feather particles, etc) of an infected chicken. Dander can be so fine that it's barely visible. Infected chickens that generate this dander may never show symptoms, so you might have no idea they are spreading the virus.
Dander can be spread via:
- Other chickens in proximity to one another, either because they are a flock, or are housed (even temporarily) in the same area, room, property, or are neighbors.
- Exposure to infected chickens seems to be the primary way Marek's is spread.
- The wind can blow dander, sometimes for miles.
- Wild birds that come into contact with chicken dander (such as birds that forage where chickens do, or roost in barns with chickens, etc) can spread the virus. The wild birds can carry the virus on the outsides of their bodies, but are NOT known to become infected. They are just little transporters.
- Rodents that track through chicken dander or litter can carry and spread the virus onto neighboring farms or properties the same way wild birds can.
- Human keepers can spread the dander on shoes, clothes, and hair, the same way wild birds or rodents unknowingly spread the virus.
- Any materials that are exposed to chicken dander, either directly or indirectly, can spread the dander.
It is important to remember that the virus can live for months or even possibly years outside of a host.
Doesn't this mean that Marek's is EVERYWHERE?
Yes and no! Marek's IS common but it is not necessarily everywhere. There is hardly any “guarantee” that any given flock or chicken will become exposed to Marek's. I have heard some say that it is not a matter of “if” but “when”, which is a little misleading. Marek's is very common and is very easily spread but should not be considered “everywhere”. Despite it not being “everywhere”, it is still important to practice good bio-security and use caution! If you like, you can imagine it's everywhere and use that to inform your biosecurity, you will be much less likely to accidentally bring it home to your flock.
Can't I cull all my chickens, clean everything, and start over?
Maybe, but it is risky, very impractical, and unlikely to totally eradicate the virus. It is important to remember that Marek's travels on chicken dander, which can blow everywhere on your property. It can live for months or even years in the environment. Even if you culled all your birds and managed to 100% sterilize your coop, the means by which to remove it from the soil on your entire property (and possibly neighbor's, if you do not have a large lot) is financially beyond the means of most backyard keepers. It is also likely you have tracked it into your home at some point. And, even if you managed to do all this, there is the chance it might come back in on the wind or a bird (etc) anyhow.
In the end it is a personal choice, but the measures to eradicate it from home, backyard, and farm type environments are extreme and it is hard to do. Most keepers opt to vaccinate new birds and/or breed for resistance.
What if I build a new coop on the other end of my property?
This is unlikely to change anything. As noted before, Marek's spreads very easily on a breeze or on your shoes, clothes, hair, when a chicken flaps, on the dog's feet when he runs across the yard... etc. It would not be impossible to imagine many ways for the virus to make it from one end of a property to another, even if the property is many acres in size. Marek's is known to spread for miles quite easily. If your property is very large you can try this, but it might be a waste of time and resources.
How long can the Marek's virus "live" without a host, such as in the soil or surroundings?
It is complex to talk about viruses as living things (most scientists consider that viruses are not living things), so for the sake of this article when I say "live", I mean "intact and still able to infect a chicken" or remain infectious. Marek's virus has been shown to be very long-lived outside of a host, as many herpesviruses are. It has been documented to live for 65 weeks (that's over a year and a half!) with no host, in an uncleaned environment. Research seems to indicate that Marek's virus lives the longest in DRY environments, such as inside coops, homes, anywhere dust can accumulate, and also in more arid climates and drought stricken areas. It seems to break down more quickly in wetter environments, such as in the soil and in moist climates where it is exposed to the elements. There is also research that indicates that solar radiation (exposure to direct sunlight) can help break down the virus capsule over time. There are many factors at play that determine exactly how long the virus can live, so it is important to 'assume' that it will be there longer than you expect. While we can get things such as coops and non-porous surfaces clean with proper cleaners (see section as to what cleaners kills Marek's virus), it is impossible for most backyard chicken keepers to clean the soil and surrounding environment, and so it must be assumed that any place that an infected chicken has been also is laced with shed virus that can live for over a year and a half at a minimum. Though it has been documented to live for over a year and a half, there are those that think it can live for over 7 years in an uncleaned environment (such as indoors, in a coop, barns, etc). There are other factors that may come into play with how long virus might live; however it has been shown to survive even very hot summers and cold winters, so you cannot rely on your environment alone to negate it.
So it's nearly impossible to eradicate. Should I still clean things?
Yes! This is still a very good idea. In fact, other than keeping your chickens overall in good health, it might be the most important thing you do. Reducing the amount of virus in your chicken's environment can only help to prevent spreading it further either on the wind, on yourself, via wild animals, etc. It is best to concentrate on areas where chicken dander accumulates, such as inside of coops, barns, etc. physically remove as much as possible (I like to use a shop vac with a drywall filter) and then saturate surfaces with a virucide to kill the virus. If you use an earthen floor in your coop, consider replacing the top few inches. If you cannot do this, research the safe use of lime in the soil. You cannot hope to completely eliminate 100% of the virus, but you can significantly reduce the amount. The side benefit to this is that by keeping a cleaner environment for your surviving chickens, they will have less stress and chance of becoming sick from a secondary illness. Anything you can do to make your Marek's positive chickens healthy and stress-free will give them a stronger immune system.
My chickens have been vaccinated, but I have or have had Marek's in my flock. Will they still shed the virus?
Yes. Studies have shown that it does not make a difference if birds are vaccinated or not-- once exposed and infected, even if they never show symptoms, they shed the virus. There is no considerable difference in the amount of virus shed, between vaccinated and unvaccinated individuals, once they have been exposed. All birds exposed to Marek's virus should be considered carriers, for life. Reference: http://www.biomedcentral.com/1746-6148/7/70
Can I use bleach?
Bleach is not known to be effective against Herpesvirus (Marek's) on porous surfaces.
What kills Marek's virus?
You want a cleaner that has a known virucidal aqgent that kills Herpesvirus. Use as directed on the label as a virucide, and always use proper personal protection! These strong cleaners can be harmful to yourself, your birds, and the environment if misued, so always follow label driections carefully. Use personal protection and a mask or good ventillation. Don't expose your birds directly to these cleaners or their fumes when using them.
The following are listed to be killers of herpesvirus. There may be others, and it's worth researching:
Odoban http://www.odobanprofessional.com/products/odoban/odoban.php
Activated Oxine http://www.bio-cide.com/uploads/Efficacy Oxine.pdf - Note, it MUST be activated to kill Marek's!
Virkon S http://www.biosecuritycenter.org/content/labelClaim/virkonS.pdf - Specifically mentions that it can kill Marek's, and on porous surfaces. Probably the best choice for very serious situations.
Article: Disinfection of Marek's Disease Virus in Poultry Dust: http://www.tandfonline.com/doi/pdf/10.1080/03079457708418232 Note that this is an older article and while still useful, it is probably best to use one of the products listed above for home use.
If you know of other viable viruicudes that kill herpesvirus, feel free to share them.
How do I keep from spreading this virus to others?
It is very thoughtful to try to keep this virus from spreading.
-It is ideal dedicate a pair of shoes as 'chicken only' shoes that you wear when you do daily chicken chores or walk in the coop. It's actually best to do this even if you have no illness in your flock! It's a great step toward general biosecurity! Keep them seperate from your other shoes and have a designated "home" for them such as a boot tray. Clean them in a shoe wash or boot bath, etc, as often as you wish. Don't wear them off of your property. If you must do so, then completely sanitize them before you go, and after you return.
-When you plan to go to a place that other chicken keepers go, such as the feed store, consider washing or thoroughly spraying your shoes with one of the virucides listed above, before you go and after you get home.
-Don't give away, sell, or show any chickens from a flock that has had Marek's virus exposure.
-If other chicken keepers visit your property, offer them baggies for their shoes, and/or dip or thoroughly spray their shoes with a virucide before they walk where your chickens go, and again when they leave. Do the same for your shoes when visiting other chicken keepers property.
Can I show a chicken that has been exposed to Marek's disease?
This is putting other chickens at the show at risk, and could be considered irresponsible and unfair. If you plan on showing chickens, it may be important to confirm if you have Marek's disease in your show birds or not. Remember that some other diseases look like Marek's. A blood test might be worth your time and money if showing chickens is very important to you.
Can I breed and sell birds that have been exposed to Marek's disease?
Again, this is putting other chickens and chicken keepers at risk. If you wish to breed and sell birds, it might be worth your time and money to get a blood test run on your breeding birds to be sure if they have Marek's (or not). While they cannot transmit the disease vertically (through the egg), any hatched chicks would become exposed upon hatching. It is possible to hatch eggs in an incubator even if the flock is Marek's positive, but EXTREMELY good bio-security measures would need to be taken and the chicks would need to be raised in very careful biosecure ways to keep any trace of chicken dander away from them. It would require a great deal of effort and dedication to keep the chicks from becoming accidentally exposed until the point of sale. It can be done but it is not easy, so consider carefully if you feel you can truly commit to it.
It may also be possible to sell hatching eggs, if you exercise extreme caution about accidental exposure of the eggs or packing materials to the virus. It would also be ethical to let potential buyers know of the risk.
Can I give one of my Marek's exposed chickens to someone else that has Marek's?
This would be risky. There are now several strains of Marek's, some of which have mutated. There is a chance that the strain that your birds have is different than the one in someone else's flock. If this were the case, it could infect both your bird and theirs and cause a new flush of symptomatic birds. Especially if any of the birds already have compromised immune systems! Do this only if the risks are acceptable. It might only complicate the problem.
How can I prevent Marek's disease in my unexposed flock?
First: Educate yourself. The fact that you have made it this far gives you a head start!
Now that you have the information, you can decide if you want to vaccinate, or not. See: Vaccinations, above. There are benefits to vaccinating day-old chicks, and possible benefits to vaccinating older, unexposed birds.
Then, do everything you can to practice good bio-security.
If you visit other areas with chickens, consider washing your shoes, clothes, and even your body as soon as you get home. Unfortunately our hair can carry a lot of dust/dander. Think critically about where other chicken keepers frequent, such as the feed store. It is not over-doing it to do a shoe wash after getting back from the feed store. In fact, it's very good habit to have shoes you use only for your chicken keeping tasks. Read on about shoes!
Shoes are a big deal! It is ideal dedicate a pair of shoes as 'chicken only' shoes that you wear when you do daily chicken chores or walk in the coop. I use easily washable rubber boots. It's actually best to do this even if you have no illness in your flock! It's a great step toward general biosecurity! Keep them separate from your other shoes and have a designated "home" for them such as a boot tray. Clean them in a shoe wash or boot bath, etc, as often as you wish. Don't wear them off of your property. If you must do so, then completely sanitize them before you go, and after you return. Try not to walk in the areas your chickens use in the same shoes that you use to go other places, such as the feed store or a park. This will protect your birds from much more than just Marek's. Now that Bird Flu is becoming more of a problem, tracking things in on shoes should be strictly avoided.
Use a lot of caution when buying, adopting, or getting new chickens from swaps, fairs, markets, Craig's list, other keepers, etc! Don't be afraid to ask questions about their flock, any past illness, any deaths in the last few years? Trust your gut if you see any red flags, and always quarantine new birds for a minimum of 30 days (60-90 is best but might not be practical for most keepers). Quarantine is not a guarantee (remember, a bird can be infected and never show signs!) but it is better than nothing. Understand the risks! Most people that bring home Marek's do so by bringing home new, already exposed birds. Backyard Chickens forums are full of stories of people bringing home new birds and watching in dismay as over the period of a few months, diseases seem to "appear from nowhere". In reality, chickens can carry illness and seem perfectly healthy, then share them weeks or months later with your flock.
Finally, do everything you can to keep your birds healthy, clean, and stress-free. Stress weakens the immune system, which invites trouble. By keeping things clean and removing dander periodically, you reduce the amount of disease vectors in their environment. And, a healthy chicken is going to have the best immune system! A good diet and low stress life is core to long-term health.
RESOURCES
If you have chickens... even if they have never been sick, now is the best time to take some time and make yourself a list of contacts. This will save you a lot of headache in case something happens. Having the information already written down can really help you cope with a chicken medical situation!
Sit down and answer the following questions, making a list where applicable
- Do I have a local avian veterinarian? (not all vets know avian biology!) Do they see chickens? What is their phone number and location? What are their fees?
- If I do not have a local avian vet, is there one that is not local that I can call and talk to for consultation? Some vets offer this while others demand to see patients in person. Tele-visit is a silver lining to the pandemic and some vets still offer it. Some are understanding about home-treatment of livestock animals, and others are not. It is worthwhile to find out now, before you have a problem, if there is a vet that will at least talk with you on the phone.
- What is my state's poultry department? Who is their poultry contact? What is their phone number? (this may be a county or state agricultural extension office, or it might be called something else-- type your state into google and "extension office" or "agricultural department", etc)
- Does my state offer necropsy on dead birds for testing? What are the fees for this? Who do I contact if I need this service? Where do I send my bird?
Diagnostics and testing
LIST OF POULTRY DIAGNOSTIC LABS, BY STATE: http://www.metzerfarms.com/PoultryLabs.cfm
LIST OF POULTRY DIAGNOSTIC LABS, via forum: http://www.backyardchickens.com/threads/necropsy-and-disease-testing-lab-info.1236884/
Texas A&M Veterinary Medical Diagnostic laboratory - http://tvmdl.tamu.edu/tests_services/test_info.php?test=Marek's-Disease-(PCR)&unit_id=1187&unit_effdt=02-JUN-10
They offer PCR (genetic/DNA) testing of blood samples for Marek's markers. Blood can be drawn from a live chicken. You may need the assistance of a veterinarian or a vet tech for a proper blood draw and/or for a sample vial. Call for up-to-date fees and any special instructions.
University of Georgia, Poultry Sciences Extension - http://www.caes.uga.edu/applications/personnel/profile.cfm?ID=4315
They have done extensive PCR testing for me via blood sample and tissue samples after necropsy. You will need to contact them to find out how to submit samples and what their fees are.
UC Davis, Veterinary Medicine (California) -
http://www.cahfs.ucdavis.edu/services/lab_locations.cfm
www.vetmed.ucdavis.edu/vme/taqmanservice/FAQ.html
Offer necropsy services and qPCR testing. I am unclear if they will take out-of-state samples; calling them directly for inquiries is your best bet! This is an invaluable service for California residents.
Contact your state's agricultural / extension offices to inquire if they preform testing. As PCR testing continues to improve with technology and up to date sciences, more and more labs offer these diagnostics. It's worth asking. If not, they should be able to point you in the right direction toward someone that does. This information is great to have on hand before you have any problems.
Poultry/Extension Labratories, by state:
http://www.aphis.usda.gov/animal_health/nahln/downloads/all_nahln_lab_list.pdf
List of State Veterinarians:
http://agr.wa.gov/FoodAnimal/AnimalHealth/statevets.aspx
Find a local avian vet. http://www.aav.org/search/index.php
This may not be possible in some areas, and not all avian vets see chickens regularly, but if you have this resource, it can be invaluable! My own vet has helped me more than I can ever say.
How to send a dead bird for necropsy, with photos: https://www.backyardchickens.com/threads/how-to-send-a-bird-for-a-necropsy-pictures.799747/
Experts in Poultry / Avian Medicine
Dr. Jarra Jange at Cornell University of Veterinary Medicine (Ithaca, NY) - http://www.vet.cornell.edu/popmed/bios/jagne.cfm
Dr. Jange is very knowledgeable about poultry and specializes in Field investigation of common diseases of poultry.
The Experts at UC Davis (California, multiple locations) - http://www.cahfs.ucdavis.edu/services/lab_locations.cfm
University of Georgia, Poultry Sciences Extension (Athens, GA) -http://www.caes.uga.edu/applications/personnel/profile.cfm?ID=4315
List of veterinarians, as compiled by BYC users, that will see poultry (not necessarily "experts") - https://www.backyardchickens.com/t/200108/list-of-vets
Note that not all of these veterinarians can be considered "experts" in avian biology. It is always a good idea to ask questions and find out how experienced a vet is about poultry medicine. In a pinch, though, sometimes any vet is better than nothing. Use your best judgement. If a vet is experienced with Marek's disease, all the better. The information about this disease has evolved and continues to do so.
Vaccines
See “Vaccinations” section.
Necropsy Tools
These can aid you if you are preforming a necropsy at home. Warning: Graphic photos!
Cornell University / College of Veterinary Medicine: http://partnersah.vet.cornell.edu/avian-atlas/search/disease/502
Take special note of the different tabs above the photos. Clinical signs are outward symptoms. Gross lesions are photos of what you can expect to find inside the bird. Normals are photos of what normal, healthy organs look like, for comparison.
University of Minnesota Veterinary Dignostic Library: http://www.vdl.umn.edu/prod/groups/cvm/@pub/@cvm/@vdl/documents/asset/cvm_asset_350829.pdf
This file contains a section on Marek's disease, as well as photographs of lymphomas.
Articles, papers, more reading
It is important to note that most scientific research conducted on Marek's disease has been conducted on large scale farming operations, typically of meat birds and production layers. Studies are very expensive and usually only commercial operations pay for them. Not on small backyard flocks, small flocks that are able to range in uncontrolled outdoor conditions, or pet chickens. Because of this, many such articles that are targeting commercial operations suggest culling all infected birds. This is because in industrial applications, the entire area where chickens live (indoors) can be treated with virucides and the virus can be completely killed off, which we cannot do in our yards. Some of the research is also out of date with the current types of vaccines used by some hatcheries and some of the mutated strains of Marek's. Use your best judgment when taking advice from this article or any other article you read. Check the dates on the articles. Don't feel alone-- many of us have been on the same frustrating and confusing journey that you are embarking upon!
The Poultry Site: http://www.thepoultrysite.com/diseaseinfo/90/mareks-disease
Mereck Vetrinary Manual: http://www.merckmanuals.com/vet/poultry/neoplasms/mareks_disease_in_poultry.html?qt=&sc=&alt=
Purdue University: https://www.addl.purdue.edu/newsletters/2005/spring/mareks.htm
World Organization for Animal Health: http://www.oie.int/fileadmin/Home/eng/Health_standards/tahm/2.03.13_MAREK_DIS.pdf
Bird Health: http://birdhealth.com.au/flockbirds/poultry/diseases/mareks_disease.html
Vaccinal Control of Marek's Disease: http://www.sciencedirect.com/science/article/pii/S0165242706000912
Various Articles by the American Association of Avian Pathologists: http://www.jstor.org/stable/i23526266
Professor Schat's Writings on Marek's disease: http://en.engormix.com/mbr-42868/karel-schat
Replication Kenetics of Marek's Disease: http://vir.sgmjournals.org/content/86/11/2989.long
ARS article on new PCR testing for Marek's as well as the development of new vaccine (August 2014): http://www.ars.usda.gov/is/AR/archive/aug14/disease0814.htm
Seminolewind's FAQ: https://www.backyardchickens.com/a/mareks-virus-the-most-frequently-asked-questions
Marek's Fact Page: https://www.backyardchickens.com/a/mareks-disease-fact-site
Bird Health Marek's page: http://www.birdhealth.com.au/mareks-disease
"How to send a bird for necropsy" with photos (forum thread): https://www.backyardchickens.com/threads/how-to-send-a-bird-for-a-necropsy-pictures.799747/
COMMUNITY
Online and offline communities can help you manage and deal with having a serious illness in your flock, via sharing information, and offering hugs through this difficult process. You can search us out or start a new thread here:
https://www.backyardchickens.com/f/10/emergencies-diseases-injuries-and-cures
There are now more resources online than ever before... if you find yourself wanting to research more deeply, go for it. Edit for 2025: Do be aware that AI generated results can be misleading, have false information, or incomplete information. Do not rely upon them. Make sure to cross reference and seek out full information form human-written papers, articles, and more. Be careful out there.
End Note:
I release this article under CC BY-NC-SA 4.0 which means: You may share and adapt this article, as long as it is with attribution, is non-commercial in nature, and is ShareAlike (your adaptation must have the same creative commons license). Full information: https://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons - Attribution - Non-Commercial - Share Alike
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Dedicated to Trousers, my sweet and wonderful cochin Rooster. He was a very special guy. RIP, Trousers. He was my first (and, with any hope, last) Marek's victim. May your life lead to the education of many.
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