How old is the chicken? It looks like tubular poop with mucus to me. Roundworms are about the only worms that you can see without a microscope. Either post more pictures of suspect poops or try to get a fecal float from your vet. Or you could go ahead and worm with Valbazen, Panacur, or SafeGuard liquid goat wormer. I can give a dosage for which one you use.