Recent Progress in the Chemotherapy of Schistosomiasis

Abstract

In 1851, Theodor Bilharz [1] found schistosome worms during an autopsy examination of an Egyptian peasant. This investigator is generally credited with being the discoverer of the disease, schistosomiasis, which in some areas is called bilharziasis in honor of the discoverer. It was not until 50 years later that the complete life cycle of the schistosome was finally worked out. Eggs from infected patients are excreted either in the urine or faeces, depending on the type of infection, and passed into fresh waters wherein a suitable snail population exists. The eggs hatch into miracidia which enter the snail and undergo a series of transformations in this vector, finally emerging as free- swimming, arrow-shaped cercariae. These penetrate the skin of humans with whom they come in contact and enter the blood stream. The cercariae lose their tails and then undergo a new series of transformations in the pulmonary and intrahepatic portal veins before emerging as sexually mature parasites. In the case of S. haemotobium the worms which mature in 10–12 weeks, inhabit the vesicular and venous plexus of the venous circulation near the bladder and discharge their eggs into that organ.

The author’s investigations on the chemotherapy of schistosomiasis were carried out at the Sterling-Winthrop Research Institute, Rensselaer, N.Y., USA. This paper was prepared for the Haffkine Jubilee, but not read in India.