Digenetic trematodes, commonly known as flukes, are responsible for a number of disease conditions in humans and many other vertebrates. They have a heteroxenous life cycle with freshwater snail as their first intermediate host. The adult stages are found in different vertebrate definitive hosts including amphibians, fishes, reptiles, birds and mammals. Disease characteristics of fluke infections vary with the parasite species and the site or organ of infection and are linked with the life cycle events like larval penetration, egg laying, etc.