Schistosomula

Penetration of the skin of the definitive host by a schistosome parasite results in a cercaria losing its tail and becoming transformed into a schistosomulum, the whole process being known as the cercarial/schistosomulum transformation (Stirewalt 1974; He et al. 2005). This morphological transformation is accompanied by dramatic changes in the physiology and biochemistry of the larva (Stirewalt 1974). Contraction and extension of the schistosomulum and the release of enzymes from its pre-and post-acetabular glands cause extensive tissue damage to all host structures traversed, until the larva breaches a blood vessel wall and enters a blood vessel. The timing of these early skin-schistosomulum stage events varies in schistosome species. Ninety percent of Schistosoma mansoni and S. haematobium parasites still remain in the host epidermis after 24 hours while within the same period a similar number of S. japonicum schistosomula will have reached the dermis or dermal vessels of the host (He et al. 2002).