Some new Comparative Investigations on Three Physopsis Borne Schistosomes: Schistosoma Haematobium, S. Bovis and S. Intercalatum

Abstract

Summary The three schistosomes transmitted by Physopsis are morphologically identical but differ in the shape of the eggs: S. haematobium eggs are round or oval; S. bovis long and spindle shaped, S. intercalatum, elongate and slender with a long, slender spine. In spite of the similarity of the parasites and the sharing of the snail host they produce completely different diseases. S. haematobium causes bilharziasis only in human beings, reproducible experimentally in primates. S. bovis causes an intestinal bilharziasis (and occasionally a concomitant vesical bilharziasis) in cattle, sheep and goats which can be experimentally transmitted to small laboratory animals. S. intercalatum, found in certain wooded regions, causes an intestinal bilharziasis in human beings which can also be experimentally transmitted to small laboratory animals. In addition, the transmission of S. intercalatum to sheep and goats has been confirmed. Since some ovides in South Africa have been found naturally infected with S. mattheei, a species or variety closely resembling S. intercalatum, the question arises as to whether we may not be dealing with the same schistosome, varying a little in its morphology in different hosts, human or animal. We shall abstain from giving a definite answer to this question, but we wish to point out that the eggs of S. intercalatum found in the feces of our experimentally infected goat and sheep were morphologically identical to the eggs of S. intercalatum found in human feces.