Helminths are the most prevalent infectious agents in humans. In the recent past, Ascaris, Trichuris, and the hookworms accounted for nearly one billion infections each, whereas the schistosomes and filariae accounted for 250 million infection each.
The typical helminths life cycle comprises three stages: the egg, the larva and the adult worm. Adults produce eggs, from which larvae emerge and the a larvae mature into adult worms.
Introduction to helminths