Hi everyone,
I have 40 grown chickens about 2 years old that have NOT been vaccinated for Marek's Disease. I also have 130 month-old chicks that have NOT been vaccinated. I have 250 layer chicks coming in a couple of weeks and am wondering if I should get these vaccinated. I plan to sell them as started pullets. I have had chickens for 5 years and have never dealt with Marek's but after reading about it I think I should begin vaccinating. I just want to make sure if I vaccinate new chicks they will not give the disease to my other birds.
Thank you in advance for any advice you may offer!
The vaccine that you and I can get is based on HVT, which is turkey herpes virus. This is a closely related Marek's virus that will cause a chick's immune system to develop resistance (with any luck) but it can NOT cause the chicken to get or spread MDV-1, which is chicken Marek's disease.
In short, vaccinating with the commonly sold live vaccine, based on HVT/MDV-3, literally can not cause the chickens to get OR spread Marek's virus. It is a different species of virus.
The reason this myth exists is that any chicken that is later exposed to chicken Marek's virus can get and spread the virus, regardless of vaccination.
Vaccination simply gives the chicken a better
chance to develop a resistance to the disease and the often fatal symptoms.
For this reason, the only risk involved with giving Marek's virus is
1) it is not 100% effective, and may be challenged by very virulent strains of viru,s or if the bird has a weakened immune system, or if the vaccine is not administered properly, and,
2) One must be careful when administering the vaccine, like all other vaccines, as improper or rough inoculation can harm the chicks physically (via the syringe). As you might imagine, if one is not careful, injury can result when poking a syringe into a baby chick.
Proper vaccination must be administered to chicks in isolation that are less than 36 hours old. Within 24 hours of hatch is ideal.
Giving the vaccine after the 36 hour period may help, or might not. But, chickens given the vaccine after 36 hours of age should never be considered 'properly' vaccinated. This is due to the unique way a chick's immune system develops in the weeks after being given the vaccine.
To read more, check out this link:
https://www.backyardchickens.com/a/the-great-big-giant-mareks-disease-faq
In the end it is a personal decision, but does not carry the same risks that other live vaccines do (such as the ILT vaccine).
