Thank you for the great info. The vet said keep her from the others which is heartbreaking because she just cries to be with them. I will definitely try the vitamins. Would it be OK if the others had them too?
If she has Mareks then it is too late to separate her from the others - as Eggcessive says the virus is spread in the dander of chickens, so it will already be in the coop, in the air and on your clothes.
If she has already been in contact with the rest of your flock then you need to consider that they have all been exposed to the virus and are potential carriers.
Therefore if she is able to be with them for all or part of a day then I would personally let her integrate - as long as you can be certain that she will not be picked on by the other members of your flock. When chickens are sick they try to hide their illness for as long as possible, as any weakness in a bird is immediately noticed by the others, who will chase the affected bird away in order to try and protect the rest of the flock from possible contamination. If she is losing balance and falling over then the other birds may well notice that and start to attack her.
I had this exact experience with a rooster who had a severe form of Mareks and from being normal one day, within 24 hours could barely stand up, let alone walk. On the day he got sick he tried to stand still for as long as possible, and then the others took no notice of him, but as soon as he moved he fell over, and they would run over and peck at him to try and get him to leave the flock. That particular bird sadly had to be euthanised, as he deteriorated so rapidly that there was no chance to save him. However I have other birds who have suffered symptoms, recovered, and continue to live long and productive lives - each bird is different, and you have to treat each case accordingly.
One way to protect your bird would be to place her in the coop / run / garden but in a box or cage that lets her see and 'talk' to the other birds without letting them attack her if they sense her weakness. That way she will have contact with the others, but without any risk.
Marek's is a terrible disease, and at the end of the day you are the person who sees your bird every day, and only you can decide if it is best to continue treating or to euthanise. Whatever decision you take will be the right one for you - no-one will criticise you for persevering with treatment or for ending your bird's suffering. Both are acceptable options, and depend upon the state of health of your bird, the available treatment options, and your ability / time to spend caring for a sick bird.
All the best for you and your bird. Please let us know how she gets on - all information is good feedback for others in our community who are going through similar problems.
