That's exactly what I do. I add new birds every year, either by hatching or hatchery. I haven't found Mareks to be a rampaging problem for me, just a nuance. In general my birds don't experience much stress which can cause Mareks to become active. That's my theory why I don't see more cases than one every year or two.Our state vet said all birds carry Mareks some just don’t express it. I haven’t and don’t know of anyone who has ever had a bird get Mareks from a show. A lot of these show flocks are resistant to it. We all practice vigorous culling and the second a bird get sick they go. It’s a good way to build up a flock of Mareks resistant birds. Cull any birds that show the signs and choose your keepers from those that don’t get it.
I personally consider Mareks is everywhere. It just depends on the resistance that birds have and a good immunity system. I don't vaccinate, I prefer to cull any sick birds, and do what I can to keep my flock healthy and as stress free as I can.