SCHISTOSOME-INDUCED PORTACAVAL HEMODYNAMIC-CHANGES IN RATTUS-RATTUS ARE ASSOCIATED WITH TRANSLOCATION OF ADULT WORMS TO THE LUNGS

The presence of naturally portacaval shunts has been investigated in t he vasculature of normal and Schistosoma mansoni-infected Rattus rattu s. Using the technique of injecting Polystyrene microspheres in the su perior mesenteric vein, we demonstrated that the presence of adult sch istosomes in the lungs of F. rattus was not due to an innate anomaly o f the rat vasculature but resulted from the formation of portacaval sh unts during infection. In rats harbouring a bisexual infection, micros pheres were only detected in the lungs from week 7. The development an d increasing size of the shunts were maximal between weeks 7 and 10 an d coincident with the translocation of adult worms from the portal tra ct to the lungs. At weeks 20-25, only 1-2 % of the microspheres were r ecovered from the lungs, suggesting that the portacaval anastomoses ha ve regressed due to reduction in portal hypertension after worm transl ocation. R. rattus with a male-only schistosome infection harboured ad ult worms in the lungs, indicating that the development of shunts does not solely depend upon egg deposition in the liver to generate hypert ension. The relationships between the presence of the schistosomes in the lungs, the portacaval shunting and the resistance to reinfection i s discussed.