Last year we purchased 12 RSLs from a local TSC store. All 12 were raised on medicated chick feed from Agway until they were 9 - 10 weeks when they started mingling with our full grown hens. When they were 18 weeks old, they started laying, except one. She started with lethargy, feathers puffed, huddled in the corner. She died at 20 weeks old. 3 months later, a second hen from the same group because lethargic, feathers puffed and huddled in the corner. I put her in our infirmary where she had diarrhea for 2 weeks and became increasingly weaker. She stopped eating and only drank and lost alot of weight. I put her out in the sun on nice days and one day she took several hours to walk back to the coop. She died the next day. Three months later, this past January, yet another from the same batch from TSC exhibited the same exact symptoms. Lethargic, puffed up and huddled in the corner with diarrhea; I brought her into the infirmary for 2 weeks and watched her lose weight until she died. Now, three months later, I have yet another hen from the same batch from TSC doing the same thing. For the past two weeks lethargic, puffed up, eating little and drinking more than anything but with diarrhea. I just left her in the coop so she could free range and be in her own environment. This morning she was out in the grass on her side, eyes closed but alive. I took her out so the others wouldn't peck her and put her in soft grass. I expect she'll have died the next time I go out.
That's 4 hens now, all from the same batch. I have 2 four year olds - 1 buff orp and 1 RSL who continue to be healthy and beautiful (knock on wood) and other RSLs, RIR and Amber Rocks from TSC and Agway that are 3 years old and while they don't lay every day, they are healthy, at least for now. Again, knock on wood. If this was a disease spreading through the flock, what could it be and would it spread this slowly?