If the Corid worked right away, it probably was. Coccidiosis is one of the more common issues chickens face. It occurs naturally in the environment and there are tons of different types, so they can get a new virus every time their environment changes. That's one reason why we have to be so obnoxiously diligent about biosecurity. We can bring a new "bug" from right next door. I thought I was good about it before my chickens got sick, but now I'm a drill sergeant on it. My kids think I'm over-doing it (shoes & waterers & such,) but if I can avoid going through that again, then I'm all for being OCD about it!
