This link has info on treating gapeworms. Thanks to Ivan3 for posting it in another thread!
http://www.ncbi.nlm.nih.gov/pubmed/6750887
Efficacy of fenbendazole against helminth parasites of poultry in Uganda.
Ssenyonga GS.
Abstract
Fenbendazole 4% (Panacur, Hoechst) administered in feed was...