We have 16 nearly 7 week-old chicks and they were doing great until about 3 weeks ago I noticed signs of coccidiosis. Lethargy and bloody stools, not good at all. The next day I tracked down some Corid after driving 2 hours to the nearest Tractor Supply that had it in stock. Symptoms eased in just a few days and within a week I thought we were in the clear. We treated for 6 days then stopped for a week as the instructions said. Last Thursday I noticed bloody stools AGAIN and a few chicks looked really pitiful. The next morning our sweet lavender Swizzle died literally in my arms after convulsing and vomiting--her BMs had been straight blood that day. I was shocked bc everything I've read says if they're still alive past day 4ish they should be in the clear. We of course started treating again and are almost finished with round two. My question is: at what point will these guys be over the hump? I know coccidia are hard to eliminate, but don't chicks who survive a bout become immune? I'm surprised that they're still trying to overcome it after all this time. Can I expect to have to go through another round of treatment or do I need to try something else? Each time the Corid appears to be working then suddenly it's back with a vengeance.