I have about 200 chickens in several different flocks. Some are in small breeding flocks of 10 hens and a rooster, and then a flock of about 90 hens and 10 roosters in a pastured hoop house that is moved to fresh grass every day. The hens in the pasture had been laying about a month when they began showing signs of illness. Some of them acted tired and just sat around eating very little. Some of those had watery eyes, some swelling around one or both eyes, and there was some sneezing. Some of the affected birds recover but some just lay down and die. Egg production in the pastured pen dropped from around 65 a day to about 6 a day. The pastured hoop house is about 100 yards from the breeder pens, but the illness spread over there anyway. Otherwise healthy adult birds seem sick for about a day then either die or recover. About half to a third of the sick birds die. The only thing I had on hand was Corrid, but that didn't seem to have any effect at all. I was going to just let this run it's course and continue on with birds that had natural immunity, but yesterday I lost my only midget white turkey hen and I'd really like to at least know what this is. Anybody know what this might be?