Remedies for ILT in a chicken flock

[hqueen13]

So the farmer I work for has about 400-500 chickens, the majority of them are laying hens. He just got a new batch of hens in, and they have managed to contract ILT, the MS and MG strains. I am not completely sure what that means, but they are not doing well. It is mostly a respiratory thing, and makes their eyes swell shut.
He tries to keep things as natural as possible, and so I'm looking for remedies. Any suggestions??
Thanks a bunch!