Significance of Worm Shifts in Experimental Schistosomiasis mansoni, with Emphasis on the Action of Anaesthetics

Abstract

ALL schistosomicidal drugs eventually cause a change of location or ‘shift’ of the worms from the mesenteric veins, where they are normally found in infected animals, into the liver. There the parasites ultimately die and are ensheathed and phagocytosed by the protective mechanisms of the host. These worm migrations may be very rapid in onset and short in duration, as occurs with antimonials¹; or they may be slow in onset and permanent in duration, as occurs with diphenoxyalkanes². Various other schistosomicidal drugs produce ‘hepatic shifts’ with intermediate characteristics. The cause of the worm migrations differs with the different drugs, but essentially it results in paralysis of the worms which are thereafter swept back by the blood stream into the liver. Where the course of treatment is inadequate, the parasites regain their muscle control and return to the mesenteric veins.