I have a good size flock of laying hens that have been generally healthy for years. Early on I lost a hen or two to Coccidiossis but that's been years. Since then, the flock has been healthy. But over the last 5-6 months I've lost a hen just about every 30 days like clockwork. The hens vary in age. They've all been eating well, laying, behaving normally. I found one dead suddenly in a laying box. The others just turn up dead in a corner of the run. They are good one day...dead the next. I have paid close attention too. I just went to feed them this afternoon and one of my healthy Silver Laced Wyandotte's was lying there dead. That's 6 in about as many months. I have wormed them some...but not consistently. All the old timers that have had chickens for decades look at me like I'm a freak of nature when I've asked them if they worm their chickens. Anyway...I need some advice as to what is mysteriously and slowing killing my flock with zero visible symptoms. Any help is appreciated.