My birds had definite worms, i fed garlic, pumpkin seeds, pumpkin, molassas feed................. Got a bit better, then still pooped out worms! (Tape and round) I do at least once a year worming. The oral ivermectin is supposed to treat roundworms and a few others, plus lice and mites

Don't always work on the lice though, depending what kind you have (heresay)
Mine ended up having both large roundworms and tapeworms (I saw living evidence, no scope needed. Bleh) So to kill that i used horse wormer paste, i would have to look up the name again. Worked like a charm, I got my info from a worming thread. Scary, i will admit to using it on one of my roosters i was going to have to have butchered anyway due to aggressiveness; when he survived THEN i dared on my hens!
I have all kinds of medical links in my siggy link; hatching, disease diagnostic charts, medicine dosing charts, etc. I am still working on it, so some things are not written down. I do have a paper notebook for what wormers work on what kinds of worms, if anyone needs to ask

The horse paste was the cheapest route and also killed the most types of worms, so that was the route i took. I think i will be doing a milder worming in the future, (oral ivermectin) but those tapes are hard to kill so i didn't mess around that time!