Agreed, I used Corid to cure my flock (some of the chicks were infected, but this worked within 24 hours and improvement in feeding/drinking was significant). But yes, the treatment must be used right when you start seeing symptoms. If you begin treating when it's maybe their fifth or fourth day of survival, the chances of it surviving may be slimmer than if it were to be one-three days or diagnoses.
Oh, sorry to hear if you lost one or two because of coccidiosis. And yeah, I've also heard that adult chickens won't die from it as easily/contract it was easily as chicks because they have stronger immune systems. The weird thing is - I had 17 adult chickens (3 of them died because of cocci) and I have over 40 chicks and not a single one died. That, however, may've been because we got the treatment for them just in time. One had cocci and lasted 3+ days with it (it takes a while for the UPS truck to ship the Corid we ordered from Amazon) so her suffering was prolonged. But, when we gave her treatment, she was immediately getting better. 3 more had cocci, but it was their first or second day of having it before the Corid came. No chicks died, but strangely 3 hens. One of them, in particular lasted over a week with it. Super odd, I felt bad because she had to suffer long, esp. since we didn't know what they were catching until it was too late!
