The Contribution of Worm Burden and Host Response to the Development of Hepato-Splenic Schistosomiasis Mansoni in Mice

Abstract

Summary Mice harboring relatively heavy worm burdens have been reported to develop hepato-splenic schistosomiasis, characterized by hepatosplenomegaly, portal hypertension, esophageal varices, anemia, ascites, bromsulfalein retention, elevation of serum globulins and increased prothrombin time. The present study was performed in an effort to determine how few worms would be necessary before the fully-developed syndrome would appear. Groups of Swiss albino female mice were accordingly infected with an average of 38, 29, 15 and 6 worms of a Puerto Rican strain of Schistosoma mansoni. Hepato-splenic schistosomiasis occurred in all four of the groups, but its onset was delayed considerably in the group harboring the least number of worms. Three mice with as few as one to two pairs of worms developed the syndrome. Mice with prolonged infections appeared to tolerate higher egg counts per gram of liver without the development of grossly visible portal-systemic collateral circulation, and with only a moderate elevation in portal pressure. This was assumed to be due to a marked regression in size of many of the pseudo-tubercles in chronically infected animals.