what’s the reason you don’t medicate from food or via injection… or at all? Do you all find coccidiosis doesn’t build up with the right care? Only I might start buying the unmedicated, lots cheaper but can be tricky to get hold of here in the uk
What medicine are you talking about? When you medicate yourself, do you take penicillin, aspirin, or imodium interchangeably? When talking about medicine I think it is important to know which medicine you are talking about. Usually medicated feed for chickens is about amprolium but the medicine in this thread is a different one.
The bug that causes Coccidiosis is pretty common. There are different strains if it, affecting different areas and having different strengths. Your chickens may or may not be exposed to various strains.
Having some of those bugs in their system is not a big deal. Two or three weeks after exposure most chickens develop immunity to that strain and just don't have problems, but if the number of bugs in their system become too great they can become ill and die.
The bug (a protozoa) that causes Coccidiosis thrives in wet conditions, specifically with chicken manure in it. If your coop and run become wet for a few days that protozoa can multiply. The chickens can get an overload by pecking at the ground or bedding. If drinking water gets poop in it that bug can thrive. It takes three days or so for that bug to mature to a point that it is a problem, that's one reason I dump my waterers at least every other day, even if they don't look dirty. And that's a big reason we stress the importance of keeping the coop and run dry. If the weather sets in wet for several days you can have issues but keeping the water clean and giving them dry places to go usually work.
I will repeat, because I think it is important. After they have been exposed to that particular strain of protozoa for two or three weeks they develop an immunity to that strain. Since I introduce dirt from the run into the brooder and I can keep my brooder dry, mine have the immunity they need by the time they are released to be on the ground.
Chicks raised by broody hens are more at risk. If the weather sets in really wet at the wrong time they could get coccidiosis. I had that happen once so I know at least one strain of coccidiosis is in my soil. If that happens and you notice it, you can treat them for the disease. I suggest you use Corid.