I have some chicken questions. I bought 2 chicks, the Brahma got very sick, I hand fed it for about 5 days. I went to the feed store where I bought it and they said it must have a concussion (Dizzy, eyes shut, wobbly, with eyes open it would turn head from side to side like saying "no", in a slow motion). At this time also purchased two more birds and asked them if the 1st could be infectous and should I keep them separate. They said they should be fine since they have vaccine for mareks. On Saturday I had class all day and when I came home, the Brahma was dead. The rest looked fine and then yesterday midday the new orphingtion started looking lethargic. She stopped eating and was standing with her eyes closed. She did not get "dizzy" so I separated her and cleaned the brooder and disinfected all the feeders, new litter, etc. By this morning, the separated orph had died. Do you think one of the living healthy chicks might be carrying something? Everything I read on BYC and online makes me think Marek's or Newcastle, but supposedly Newcastle is not in the US and they were all vaccinated by the feed store for Mareks. They are eating Purina Grow & Start and their water has added a solution of DURVEST vitamins and electroytes. The live ones seem perfectly fine, running around, eating, drinking and acting very normal. My big question is what will happen if these last two make it and I introduce them to the older hens flock when they are 2 months? OR should I cull them OR should they remain separate? What should I do with the 2 survivors if they remain healthy? Is it safe to get more, or should I stop?