I am so sorry that you are dealing with this. I too know how you feel!
I followed the advise of the vet. I culled my whole flock. I have cleanned , put in sand etc. I however will never feel positive that it will not happen again. I have waited 3 months to reintroduce chicks and will use virkon s as a follow up disinfectant before the chicks go in. I have already done the clorox disinfection route. The mg/ms hit during the winter when my hens were under a lot of stress from winter. Mine was MS more than anything and yes it was congestion and clear runny nose. I lost one hen and had them all tested. How did they get it? They do not range free and no wild birds were in the pen but droppings could have gotten in. Also I had a rat problem just before it started. There were so many ways it could have come in. My flock had tested neg. 4 months before.
Mine were more pets than anything and I don't think I could go through that again. I would probably just keep a closed flock. I do not sell chicks anyway. If anyone wanted one and I had extra I would give them away. Now, no more give aways unless I have just checked them. I had hens for 3 yrs without this happening maybe I can go a long time this time too.
I wish you the best of luck with your answer to your question of flock culling. It is so hard. Gloria Jean

Mine were more pets than anything and I don't think I could go through that again. I would probably just keep a closed flock. I do not sell chicks anyway. If anyone wanted one and I had extra I would give them away. Now, no more give aways unless I have just checked them. I had hens for 3 yrs without this happening maybe I can go a long time this time too.
I wish you the best of luck with your answer to your question of flock culling. It is so hard. Gloria Jean