OK, i heard lots of you said that your chickens are fine one day and are found dead the next so i started to read. in the book Storey's Guide to Raising Chickens pg. 167 i found a disease that caught my eye. it's called Septicecemia. it occurs when an infection reaches the bloodstream. signs include weakness, listlessness, lack of appeite, chills, fever, dark or purpleish head, prostration, and death. Acute septicecemia hits a bird so fast that it can drop in its tracks. but most septicecemia cause reduced appitite and weight loss before death, the classic indication of acute septicecemia is the sudden death of an apparently healthy bird that has a full crop and in good flesh. but i am sorry to say there is no cure to this that i know of.