Vaccinated Chickens Transmit Marek's Virus and Can Kill Your Unvaccinated Chickens.

[LisaMP]

"Marek's vaccination is what they call a "leaky" vaccination in that it prevents death of the host but does not prevent infection or transmission, and it allows the virus to become increasingly "hot" or more deadly. Vaccinated chickens who become infected (asymptomatically or not) transmit 10,000 times more of the deadly virus than an unvaccinated bird. Because of the way a leaky vaccine causes the virus to evolve, the virus is now so strong now that it has the capability of killing 100% of unvaccinated chickens the vaccinated chicken comes into contact with."

Well, Damn, this is exactly what happened to me last Summer. Bought 2 pair of Vaccinated chicks from an NPIP breeder and all hell broke loose. I lost over 50 juveniles last year, nearly everthing I hatched, through October. First 3 necropsies only showed Coccidiosis, which the ground zero birds Also came in with (which the breeder did advise me of once they arrived here safely). All I did was treat and disinfect all summer, and watch birds die and put down symptomatic ones. Fourth Necropsy in September finally proved positive for Marek's. Interestingly, two of the four purchased birds Also died. The Second pair remained healthy all the way through.

Now I have 60+ surviving chickens on property that have all been exposed. My adults, and about a dozen babies that survived the onslaught. Obviously I'm done breeding, can't move any of them on, and don't have the heart to clean house, as frankly, they are the ones who were strong enough to survive this mess. It's a good thing that where I live, there's no limit on the number of roosters I can have because half the surviving babies are Roosters.

Now I wait to see if, when Spring arrives and the weather warms, if it blows up again. Did the cold weather cause it to go temporarily idle? A macabre science experiment.

 

[SourRoses]

Really simply... the Mareks vaccine uses the Turkey variant of Mareks. It can't infect Chickens, but it can tell the immune system how to make antibodies.
If a vaccinated bird contracts the Chicken variant of Mareks, it won't get very sick, but its body will still have some work to fight it off (vaccines aren't magical shields) which leaves them as carriers that can spread it.
It's the actual Chicken variant of Mareks, contracted from other birds or the environment, which is responsible for the illness, NOT the vaccine.
Neither the Vaccine nor Chicken Mareks is responsible for any other diseases, no matter the timing.
It's so important to remember... More than one thing can be true at the same time.
We have this deep rooted urge to trace things back to a single cause. But reality, especially when it comes to medical issues, can be a lot more complicated.

 

[LisaMP]

In over 20 years of keeping and breeding chickens I NEVER lost a bird to Marek’s symptoms until this past season. As I added breeds and breeding stock, 99% of the time I purchased fertile eggs and hatched them out myself.

When I bought those 4 birds, 1 pullet proved a bit punky out of the box. I chalked it up to shipping stress. Then the breeder responded that she’d found bloody stool in the brooder after she shipped them, I chalked it up to the coccidiosis and treated, but she remained punky.

Stupidly I had put those babies in my brooder room. In a separate cage, but I had 4 brooders of chicks in there. The deaths started in there, not out in my mature flocks. Once the first necropsy came back coccidia, I treated everything Again with Corrid, and then when things seemed clean started moving the 6-8 week olds outside. It came in waves.

I kept hatching and raising because I thought I was dealing with a tough strain of coccidia from those birds.
End of September the last necropsy finally came back posit ive for Marek’s. Of those 4 birds that were vaccinated by the producer, the Mille Fleur pair died. The Golden Necks never had a bad day and are still fine. .

 

[LisaMP]

According to this, and from my research, current vaccines include chicken virus to increase effectiveness of the vaccine.
This is why the vaccine must be shipped frozen, increasing the cost.

 

[LisaMP]

And this …

 

[HappyHippyChick]

I heard that raising turkeys with chickens will ensure chickens will not get Mareks.

 

[Sammster]

Ok, I have a question. I have 8, unvaccinated hens. I'm getting 4 new chicks in the spring. Vaccination may be an option. Should I or shouldn't I, get the new chicks vaccinated?

 

[LisaMP]

I heard that raising turkeys with chickens will ensure chickens will not get Mareks.

I’ve heard that, and I’ve also heard it’s Not true.
BUT, my only 2 pens that did not experience deaths last year are my pens that run alongside the goat pen where I also had 3 turkeys residing for the past 3 years. One of the pens contains Bantam Cochins, which are supposed to be particularly susceptible to Marek’s. So by practical experience it very well May be true.

 

[LisaMP]

Ok, I have a question. I have 8, unvaccinated hens. I'm getting 4 new chicks in the spring. Vaccination may be an option. Should I or shouldn't I, get the new chicks vaccinated?

From all my reading, and my experience, vaccinated chicks are fine. They’re vaccinated at hatch, and aren’t exposed to adults. I think hatchery chicks also get the more extensive forms of the vaccine that cover more variants.

My “ground-zero” birds were vaccinated by a private breeder, and were also about 10 weeks old upon arrival, so most likely encountered exposure after vaccinating. Keep in mind the vaccine doesn’t prevent the disease, only suppresses transmission and development of the internal tumors and such.

I never had problems mixing vaccinated day-olds with my flock.

 

[Sammster]

From all my reading, and my experience, vaccinated chicks are fine. They’re vaccinated at hatch, and aren’t exposed to adults. I think hatchery chicks also get the more extensive forms of the vaccine that cover more variants.

My “ground-zero” birds were vaccinated by a private breeder, and were also about 10 weeks old upon arrival, so most likely encountered exposure after vaccinating. Keep in mind the vaccine doesn’t prevent the disease, only suppresses transmission and development of the internal tumors and such.

I never had problems mixing vaccinated day-olds with my flock.

Thank you, Lisa