I have used plain yogurt for bacteria. Apple cider vinegar, garlic, pumpkin, and Diatomaceous earth for worms. DM is also good for external parasites. But sometimes I give up and use Ivermectin, Tetracycline and Cocci-Stat. Now knowing when a bird is beyond my natural approach, I sometimes pull out the heavy artillery. I know that a natural flock is a stronger flock, but sometimes losses get out of hand. Opinions?