Marek's vaccinated birds as carriers

[Beth C]

I started vaccinating for Marek's several years ago, after it practically decimated a shipment of pullets I'd ordered to resell. Prior to that, none of my birds had been vaccinated. I knew the vaccine is only recommended for day-olds, but I had plenty of leftover vaccine so I hit the adults, too - figured either a) they hadn't been exposed and it would protect them or b) they'd been exposed, were resistant, and it would do nothing. I had no problems with any  of them, and I've had several chicks that never got the vaccine because they hatched under broodies. Knock on wood, no issues with them either. However, someone recently raised the question of introducing vaccinated birds into a flock of unvaccinated birds, since the vaccinated birds could still be carriers. So I guess there are 2 main questions that I could not answer:

Is it safe to mix vaccinated & unvaccinated birds, such as someone with an unvaccinated flock purchasing a single vaccinated bird, and if so, because it's a live vaccine, how long after vaccination should you wait before introducing them?

If a breeder who has not been vaccinating for Marek's wishes to begin doing so, how should they handle the older birds? I kind of assumed that, since I'd had an outbreak, anything still alive was likely resistant, but if someone is unsure if their birds have ever been exposed, they might want to proceed differently.

edited to add: I'm pretty sure this has been covered before, but we all know I'm search-challenged!

[John]

I don't have the answers...just a link to Wikipedia with some words that I can't pronounce.
http://en.wikipedia.org/wiki/Marek's_disease
This quote, from the link above, is a good one to refer to when folks wonder why the vaccinated chicks they bought seem to get the Marek's.

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.

[Mike Gilbert]

According to that quote, vaccinated birds are less risky to spread Marek's than unvaccinated birds in a flock where the Marek's organism is present.   Since Marek's can and often is everywhere in the environment, and can be spread by wild birds according to some sources, the only reasonable thing to do is vaccinate when possible and breed for immune strains.   There will be losses;  it's a part of the game.

[John]

Here is a link to a site that has an article on the subject.  I don't know the writer, but have seen the name in the Poultry Press.  He/she is a contributor and sounds knowledgeable.

http://www.shagbarkbantams.com/page9.htm

Personally, I'll keep mixing the birds together, vaccinating some while not vaccinating all.  Some die...some don't.   

[Sharon Yorks]

I am just now reading this post and can tell you that this is a question that I had a month or so ago, so instead of researching articles from others, I decided to call the manufacturer of the vaccine and find out first hand. I was informed that this vaccine does not transmit the actual virus to unvaccinated birds. If anything, it may help them. The vaccine is shed, but not the virus. There really isn't much "protection" given to the unvaccinated birds, (by being exposed to vaccinated ones) but there is in NO way any harm of the Mareks virus transferring.

They told me that there is somewhat of a race against time to what the chicken will be exposed to first, the Mareks vaccine or Mareks itself, that's why they say vaccinate at 1 day old. I vaccinated a couple of bantams I had hatched at the same time, but I used a half of a dose, thinking they were smaller and there were no instructions for that. When I talked to the lady a week or so later, she told me that the bantams should get the same amount of dose as the large foul and that I should go ahead and vaccinate them again with the full dose.

I asked her about vaccinating the older birds and she said that it wouldn't hurt them, but that they (since they were over a year old) have probably already been exposed and/or built up a resistance to it. This is my first year of vaccinating chicks so I am just getting comfortable with holding small chicks and vaccinating under the neck skin. I wasn't comfortable with the idea of trying it with a full grown bird. If I'm understanding her correctly, there is never a risk of vaccinating any of your birds.

But to answer your question, Yes...it is safe to mix Mareks vaccinated birds with unvaccinated ones. The Mareks vaccinated bird does not shed the actual virus, just the vaccine. This vaccination is NOT the same as some others, such as the LT vaccine.

I will try to locate the number of the Mareks Vaccine manufacturer and post it so you can call them first hand. I am always one to go straight to the source if they are available.

Hope this helps,
Sharon

[Sharon Yorks]

Here is a link to the Mareks Vaccine Manufacturer (Pfizer) website: https://animalhealth.pfizer.com/sites/pahweb/US/EN/Conditions/Pages/Marek_Disease_MD.aspx

And here is their telephone number: 855-424-7349 - https://animalhealth.pfizer.com/sites/pahweb/us/en/contact/pages/contactus.aspx

There's a lot of other information on their website, too.

[Beth C]

Awesome!! Thanks so much!

[dak]

Does anyone feel that the Lavender/Self-blue variety is more suseptible to Marek's than other varieties?  I seem to be having a problem with these and my bantam Brahmas this year.

Clare

[Mike Gilbert]

Clare, I don't know about lavenders as I never raised them.  But my black bantams were always more susceptible than, say the buffs or wheatens.     Since the lavenders are diluted blacks, I would suspect they might be, but then I suppose there is more than one strain of blacks out there too.  Vaccination will take care of about 98% the problems based on my own experience, and I have been vaccinating since 1997.

[Birdcrazy]

Mike, I think you are right about the black line being more suseptable to mareks. I bought some unvaccinated Black and Blue Ameraucana chicks 3 years ago. I had never had experience with Mareks desease until then. At about 3 months of age I started losing chicks. I did some reading and diagnosing and they died from classic mareks paralysis. By the time I ended the year, I lost about 70% of the chicks I bought and chicks that I hatched. I was as devestated as my flock was, and about to throw in the towel. I even had about a 10% loss of adult birds. It seemed it really hit the Black and Blue Ameraucana (both LF and bamtam) lines exceptionally hard. Self Blue O. E. bantams, and some Easter Eggers I had raised for several years years with no problems, also were hit hard. My Silver Duckwing and BBR Old English seemed pretty much immune as well as my Black, Blue, Splash, and Silver Laced Wyandotte bantams. I have been vaccinating all day old chicks for the past 2 years ( abt 800) and not lost any to mareks. I have not been brave enough to risk not vaccinating some chicks now for a test as the vaccine is fairly inexpensive and I have to pitch unused mixed vaccine anyway. Much thanks to those who engineered the vaccine!!!!!!!!

[dak]

Yes the vaccine is cheap, but the shipping isn't.  I will vaccinate next year and just have to bear my losses this year. 

Strangely enough, my LF Cochins/Brahmas seem untouched.

[Birdcrazy]

I buy mine from Smith Poultry and Game Bird Supply, Bucyrus,Ks. I usually plan ahead and call Terry and have her bring to a show or exotic sale they are displaying at. All I have to do is take a cooler and ice along to keep it cool till I get home. That way there is no shipping cost.