well if they are laying I would say they have all been exposed and have a resistence to it. and you should not have any problems.
In the future with new chicks you maydeside to vaccinate for it now that you think you might have it, although is sounds like the strain you have is not ver strong (trust me there are ifferent strengths and having one just a little paralized but still eating and now getting better probably means the strain you have is not too bad) If you do vaccinate find a place where the chicks can be brooded in complete isolation for the first 10 days from anything (cloths, dust, ect) that might have traces of Mareks on it.
Good Luck so happy to hear she is improving
Moody Chicken is awesome
In the future with new chicks you maydeside to vaccinate for it now that you think you might have it, although is sounds like the strain you have is not ver strong (trust me there are ifferent strengths and having one just a little paralized but still eating and now getting better probably means the strain you have is not too bad) If you do vaccinate find a place where the chicks can be brooded in complete isolation for the first 10 days from anything (cloths, dust, ect) that might have traces of Mareks on it.
Good Luck so happy to hear she is improving