Should it be Paratyphoid eliminating those showing signs of it isn't a sure way of eradicating it from your lofts. The problem being pigeons can harbor Paratyphoid without ever showing any signs, these are carriers and can pass it on. I suggest you take professorial advice, a good place to start would be to contact http://forum.pigeonbasics.org/user/2567-david-vet/ I'm all for natural immunity but some diseases cant be left to run its course............. Paratyphoid is one of them. Hope you get it sorted.