Schistosoma intercalatum infection in Syrian hamsters. An experimental and histopathological study

Syrian hamsters were infected with increasing numbers of circariae of Schistosoma intercalatum and Schistosom mansoni. Various organs were then studied histopathologically. These studies revealed a relatively higher pathogenicity of S. intercalatum in rodents than in human cases reported in a previous communication. Yet the magnitude of infection and its complications were milder in cases of S. intercalatum than in S. mansoni. The absence of liver fibrosis or cirrhosis in S. intercalatum infection is in agreement with our previous experience with human subjects. It is apparent that this parasite produces much more pigment than S. mansoni and the other well known types of Schistosomas. The development of the granulomatous reaction, mainly in liver, rectal mucosa and in lung parenchyma of infected animals seems to be a similar process in all types of Schistosoma infections without major qualitative differences and irrespective of the density of infection. The worm load as roughly indicated by the worm return through perfusion is not always indicative of the severity of infection since a very low worm load in a long term infection can lead to the same results as a short term very dense infection. Some evidence suggesting the possibility of 'reaction' around pulmonary blood vessels, not related to the granulomatous lesion was found. This finding requires further immunological investigation.