Pharmaceutical compositions having at least one crystal protein and a nicotinic acetylcholine receptor agonist in amounts effective to inhibit a parasitic worm or helminth infection in a vertebrate or mammal are described. Methods for treating a parasitic worm or helminth infection in a subject are also described. The methods include administering to the subject a therapeutically effective amount of the at least one crystal protein and a nicotinic acetylcholine receptor agonist. The crystal proteins can be isolated from Bacillus thuringiensis and include Cry5B, Cry21, Cry14A, Cry6A, and Cry13A. The nicotinic acetylcholine receptor agonist can be from the levamisole family, which include levamisole, pyrantel, and tribendimidine.