To Vaccinate or Not (for Mareks)

We have recently had several customers report loosing chicks early for no apparent reason. The chicks seem fine upon transfer to the new brooder and even thrive for a day or so. Then, suddenly, one chick develops lethargy and dies 6 to 12 hours later. Given that other chicks in the brooder are doing fine, the temperature is good, etc., etc., it is most likely a vaccine reaction that is killing it.

This experience fuels the debate on whether or not to vaccinate chicks for Mareks. Until the past few years, the backyard enthusiast has not had to worry about the virus that causes Mareks. However, as I’ve reported before, with the popularity of backyard flocks growing, there are more and more flocks for the virus to leapfrog.

My feeling is that I would rather take the risk of loosing a few more chicks by vaccinating and us (as a business) having to replace them young, then have people invest 6 to 12 months in raising a bird only to have it develop paralysis and die a slow, painful death. When people have just a few birds, they invest a whole lot more time and energy (both physical and emotional) in raising them, which makes the loss of one more difficult when they are older.

If you are a backyard chicken owner, I would appreciate your comments on this topic. Your insights may influence what we do with regard to vaccination.

8 Responses to “To Vaccinate or Not (for Mareks)”

  • Laura Mitchell:

    As a person whose flock has been hit severely hard by Marek’s disease (six deaths in a year from a batch of 12 we started raising March 2012), I would never consider having chicks that hadn’t been vaccinated against this disease. When you only have a dozen birds and you raise them from babies, it is horrible to watch this disease decimate them. Only one of our losses was quick and unexpected…the rest were slow and painful with varying degrees of paralysis and lethargy. I recently had someone offer to give me free chicks (a photographer that had gotten them for Easter shoots); my only condition on taking them was I *had* to know they were vaccinated for Marek’s!

  • Brian Gurley:

    I am still brand new to this hobby. I got my first chicks in June of 2012. I have not had any problem and so far have not lost any chicks. My first batch was a small group of 5 chicks. They are all laying and doing very well. I do have one GLW that has just decided to go broody.

    Four weeks ago I bought 6 more chicks from Tractor Supply. I wondered how they would do compared to the chicks I got from you. But so far, they are all doing very well and growing like crazy. I think you should keep up the vaccinations. If I had an option to buy chicks with or without, I would ALWAYS PICK WITH! Better safe than sorry.

  • Trish Radford:

    I’m one of those backyard chicken owners who has had to deal with loss from Mareks. It was extremely heartbreaking to watch my pets suffer and die from the paralysis. I started losing hens at about 13 weeks of age and ended up losing four of the six I bought last year. Don’t know if the hatchery actually gave the vaccine or if the vaccine was not given within the short time frame after mixing. Nonetheless, I firmly believe that all chicks should be vaccinated at one day old due to the prevalence of Mareks. I understand it can be spread thru the air for up to 20 miles and once it’s in your soil it’s pretty much “there.” I plan to get more chicks this spring, but will never knowingly bring any chicks here who have not been vaccinated for Mareks.

  • jimmy lloyd:

    I think your reasoning for vaccinating is sound, and makes us feel better about our hens’ health. Makes me wonder, though, if the chicks shouldn’t be kept in your brooder for a longer period of time before making them available for sale. As you indicated in a conversation with me, the whole relocation can stress them pretty bad especially with the cold weather leading to rapid temperature changes for the chick. Is there a standard “adoption” age for chicks, like say 9 or 12 weeks for a kitten? Not that the period of time would be 9 or 12 weeks, but is there a minimum time you like to keep them before selling them? I don’t know enough to know if this even makes a difference. Thanks for the chance to discuss…

  • I believe they should all be protected. It is sad to see them get sick and die when the disease could have been prevented.

    Is it possible to get the vaccine and give it after we have the chicks from somewhere they were not treated? Is there an age limit on giving the Mareks vaccine?

    Are the large hatcheries required by law to vaccinate chicks before they are sent out or it is their choice to do so or not?

    • Hey Cookie. We believe the same. That’s why we made the decision a couple of years ago to have every chick vaccinated. However, we never posed the question. Since there is a risk to the chick, I thought it would be good to get people to weigh in.

      Birds must be vaccinated before they are exposed to the Mareks virus. For this reason, it is strongly recommended that chicks be vaccinated on the day they hatch. However, there is proven efficacy for vaccinating up to a week after hatching. The challenge for home hatching is that the vaccine is only sold in 1000 dose vials. And once mixed, it’s only good for a few hours.

      Hatcheries do not automatically vaccinate. It has to be ordered and there is a per bird charge.

  • jeffrey:

    Poultry Professor – My question, since Mareks occurs naturally and all backyard flocks are considered to be exposed vaccinated or not, how do you raise chicks under broody hens with success? We generally do not use an incubator, but use broody hens to raise our chicks. So, I am curious what the best method to keep these chick from dieing off in 5 months or is there really anything you can do? My understanding is they would be exposed immediately after hatching from the hen so vaccinating would not be effective? Any advise for folks that raise chicks naturally?

  • Hi Jeffery,
    the short answer is that not all of your flock will be affected, even if exposed. Morbidity (meaning the expression of the disease) ranges between 10 to 50% of an infected flock depending on the strain of virus. Of the flock that shows symptoms, mortality is as high as 100%. So, if your flock is infected and the biddies are not vaccinated, you would see anywhere from 1 in 10 to 5 in 10 show signs of Mareks infection.

    The virus is shed from skin cells. Dust and dander around the coop is the culprit. It can survive for months in the dust. (And that’s why it can travel up to 25 miles.) The introduction of vaccination programs has significantly reduced the spread of the disease. The more vaccinated birds there are the fewer vectors there are to spread it. There is not a problem letting your birds hatch their own biddies. If you begin to see losses due to Mareks from these birds you would want to stop the practice for a year or so and introduce vaccinated birds to your flock. Also, stepping up cleaning of the coop will reduse the amount of potentially infective dust.

    For more information, read:

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