Specificity and Immunobiology of Larval Digenean–Snail Associations
Coen M. Adema, Eric S. Loker
Abstract
Egyptian hieroglyphs dating to 1500 BC described a (questionable) cure for the “worm in belly” causing the hematuria associated with Schistosoma haematobium infection in humans. 1 Although adult digenetic trematode (digenean) parasites and their pathological effects were recognized long ago, the intermediate hosts in digenean life cycles were not identified until the late nineteenth century, when Leuckhart 2 and Thomas 3 independently demonstrated that the life cycle of Fasciola hepatica (causative agent of liver rot) involved an intermediate host, the gastropod Lymnaea truncatula. The discovery of this digenean-snail association sparked efforts to identify the intermediate hosts of other medically and economically important digeneans. 4 This work subsequently demonstrated that most snail species do not support the life cycle of a particular digenean species: digeneans and molluscs are specifically associated with one another.