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Section 11 – Helminthic Infections

Chapter 82 – Schistosomiasis

Andrew Davis

The term human schistosomiasis includes a complex group of acute and chronic parasitic infections caused by mammalian blood flukes (Schistosoma). These infections are transmitted by specific aquatic or amphibious snails in a wide variety of freshwater habitats.

The various species of the genus Schistosoma are members of the family Schistosomatidae-dioecious digenean parasites whose habitat is the blood–vascular system of vertebrates. The family is divided into three, the Schistosomatinae, Bilharziellinae and Gigantobilharziinae, and contains 12 genera, of which several are confined to birds and five to mammals; only Schistosoma is associated with humans.

A general feature of the family is that the female is longer and more slender than the male and is normally carried in a ventral groove, the gynaecophoric canal, formed by ventrally flexed lateral outgrowths of the male body. Of all the mammalian blood flukes, the genus