Trematoda

Trematoda is a class of parasitic flatworms commonly known as flukes, within the phylum Platyhelminthes. Nearly all trematodes are internal parasites of vertebrates as adults, with complex life cycles that typically pass through one or more intermediate hosts, most often a snail, before reaching a final vertebrate host. The class includes medically and economically significant species such as the blood flukes that cause schistosomiasis and the liver flukes that infect livestock and, in some regions, humans.