I have 1 girl who is very sick, and 2 who are not. All were supposed to be vaccinated when I got them as day old chicks, they are now around 24 weeks. I think it might be Markes but not sure. If so can they others get it if they were vaccinated? I think I keep a pretty clean coop and run,what else can I do to try and keep the others from getting sick? If she does live and she go back with the others?