The WHO estimates that almost 2 billion people are infected with one or more ofthese soil transmitted helminths, accounting for up to 40% of the global morbidityfrom infectious diseases, excluding malaria. Out of these, approximately 300 millioninfections result in severe morbidity, which are associated with the heaviest wormburdens. In recent years much new information has been obtained about the epidemiology,population biology and public health significance of infections of intestinalhelminths in humans.