Can vaccinated chicks spread Marek's to unvaccinated chicks?

[mikic]

We have added to our flock over the years, some adopted from neighbors who decided chickens weren't for them, so we are assuming not all our birds were vaccinated against Marek's as chicks. We purchased seven 1-day old chicks from Meyer's and had them vaccinated against Marek's. They are 4 weeks old now.

The Merck website states that "Marek's disease is identified in chicken flocks worldwide. Every flock, except for those maintained under strict pathogen-free conditions, is presumed to be infected." It states that vaccinated chicks exposed to the virus will not develop the disease, but can shed it to any unvaccinated birds in our flock. So, assuming that the hatchery that we purchased from has Marek's in their flocks and our vaccinated chicks were exposed to the virus, should we be concerned about them shedding the virus to our unvaccinated birds?

One of our existing bantam hens has been sitting on eggs and we expect them to hatch any day now. We will place them in a separate brooder inside the same building where the 4 week old vaccinated chicks are. Should we be concerned that the vaccinated chicks may infect the hatchlings?

 

[JacinLarkwell]

We have added to our flock over the years, some adopted from neighbors who decided chickens weren't for them, so we are assuming not all our birds were vaccinated against Marek's as chicks. We purchased seven 1-day old chicks from Meyer's and had them vaccinated against Marek's. They are 4 weeks old now.

The Merck website states that "Marek's disease is identified in chicken flocks worldwide. Every flock, except for those maintained under strict pathogen-free conditions, is presumed to be infected." It states that vaccinated chicks exposed to the virus will not develop the disease, but can shed it to any unvaccinated birds in our flock. So, assuming that the hatchery that we purchased from has Marek's in their flocks and our vaccinated chicks were exposed to the virus, should we be concerned about them shedding the virus to our unvaccinated birds?

One of our existing bantam hens has been sitting on eggs and we expect them to hatch any day now. We will place them in a separate brooder inside the same building where the 4 week old vaccinated chicks are. Should we be concerned that the vaccinated chicks may infect the hatchlings?

They will only infect the unvaccinated if the vaccinated birds were exposed to mareks. The vaccine doesn't prevent it, just the symptoms that kill/paralyze the bird (as long as they were kept from the virus for 2 weeks after vaccination and the strain isn’t a super bad strain)

 

[mikic]

They will only infect the unvaccinated if the vaccinated birds were exposed to mareks. The vaccine doesn't prevent it, just the symptoms that kill/paralyze the bird (as long as they were kept from the virus for 2 weeks after vaccination and the strain isn’t a super bad strain)

So, we should assume that the Meyer's hatchery has Marek's in their flock but the day-old chicks were kept in a separate area and not exposed?

 

[JacinLarkwell]

So, we should assume that the Meyer's hatchery has Marek's in their flock but the day-old chicks were kept in a separate area and not exposed?

Yes. The eggs are cleaned and incubated in a separate area, and day olds have no contact with the breeder flocks

 

[K0k0shka]

The virus is not transmitted via the eggs, so if the hen that laid the eggs was infected, the chick in the egg will be clean. So the chicks hatch clean. Hatchery eggs and chicks are usually kept in a separate area, so it's unlikely that the chicks that hatched clean will get it from the breeding stock. It's transmitted through dander though, which is impossible to detect on surfaces, so if the humans tending to the chickens go back and forth between the adults and the chicks without good biosecurity measures, then it's possible to transfer it from the flock to the chicks that way. But Marek's can also just be in the environment outside. It can blow on the wind and infect your flock. So your new chicks aren't the biggest danger to your adult flock. Even if you hadn't gotten new chicks (vaccinated or not), your adopted birds of unknown vaccination status would've been vulnerable regardless, just from living outside. So they'll just have to take their chances. I would vaccinate the bantam's chicks after they hatch though, just for their own sake. You may never get Marek's in your area. Or you might get it (it's spread by wild birds so out of your control), in which case you'll soon find out which birds were vaccinated. It can absolutely devastate an unvaccinated flock. So if you don't feel like playing such a game of chance, vaccinate your new chicks to give them their best chance.

 

[realsis]

Also I wanted to add the vaccine is derived from the turkey varrient of Markes immunity. So no worries of shedding a chicken virus there. I get my flocks from Meyers as well. I vaccinate the chicks and has never had a issue. Over the years I've been very pleased with that hatchery and I live all the way in California. It's quite a trip but I haven't lost more than one. There birds are usually healthy and strong.

 

[K0k0shka]

Also I wanted to add the vaccine is derived from the turkey varrient of Markes immunity. So no worries of shedding a chicken virus there.

The concern wasn’t that they’d shed virus from the vaccine itself (they can’t do that), but from a potential infection with the actual disease, since vaccinated birds can still contract and spread it, they just won’t get seriously sick or die so you may not even know they contracted it.

 

[Sylver Queen]

I'm jumping in on this thread since it's newer. Long story short, symptoms of Marek's in my flock for the first time in 13 years. But in researching quite a bit I managed to come across a statistic that vaccines are actually more effective in older birds than they are when given to day-old chicks and the reason we give to day-olds is because if the vaccine is given after exposure it won't work. That makes perfect sense, but if a four-week-old chick has for sure not been exposed, why not vaccinate? Anybody know? Thanks for any info!