I have a coop that I cannot use any longer for similar reasons. I have never been able to determine the problem. I have thoroughly sprayed to kill insects, then thoroughly cleaned and disinfected, let sit vacant for months and months, but if I try to use it, the birds get ill.
Try to think back to the first time a bird got ill--had you done anything different in the week or so preceding the illness? Think about having a necropsy should another die.
Try to think back to the first time a bird got ill--had you done anything different in the week or so preceding the illness? Think about having a necropsy should another die.