My first two chickens died of mareks disease. After the first one died we got a friend for her who we still have (who was mareks vaccinated). It was only when the second of the original chickens died that we knew we were definately dealing with marek's disease. I bought two more mareks vaccinated birds to keep the remaining one company. Some months on all seems fine but the other day I read that the marek's vaccine doesn't stop them getting mareks it only stops the tumours developing,is this true? Are my vaccinated hens in danger of becoming sick as a result of the mareks they have undoubtedly been exposed to?
Welcome to BYC. There is a thread her that has many knowledgeable people who deal with Mareks in their own chickens. Asking a question on that thread will get good answers. Here is a link: https://www.backyardchickens.com/t/741957/not-an-emergency-mareks-in-the-flock
The Marek's vaccine protects the chicken that it is given to-- it prevents the development of tumors. However, a vaccinated chicken can still get the disease and carry it (but won't show symptoms, and usually won't be harmed by it itself). Its likely that since your birds are vaccinated, they will not become sick because of Marek's, but it is still possible. About 5-10% of vaccinated birds will still get the disease.
The answer is Maybe-- sadly, an all too common response when it comes to questions about Marek's!! I have responded in more detail in this thread: https://www.backyardchickens.com/t/741957/not-an-emergency-mareks-in-the-flock/1690#post_12603546 I also have a FAQ in my signature that has some more in-depth writing about the vaccine... which ones exist, what it does, etc.
