Helminthology, medical

The field of medicine that pertains to helminths (worms) capable of disease in people. For more about these worms, see "Helminth." The public health impact of medical helminths is appreciable. Two billion people are infected by soil-transmitted helminths such as Ascaris, hookworms, and Trichuris trichiura and by schistosomes. Early childhood infections by soil-transmitted helminths delays physical and cognitive development. Other widespread helminthic infections include onchocerciasis, lymphatic filariasis, dracunculiasis (Guinea worm disease), and food-borne trematode and tapeworm infections. All of these infections cause chronic morbidity and debilitation. Medical helminths need to develop in a parasitized host, and sometimes this involves several disparate hosts. Helminth parasites are more complex than free-living helminths, because they have evolved mechanisms to deal with the different environments of their various hosts and living conditions. They have developed host-finding behaviors, exquisite migration patterns within each host, and the ability to evade the host immune and protective responses.