The Bottom Line: Disease after infection with Schistosoma mansoni develops primarily as a consequence of chronic granulomatous inflammation in the liver. This results in hepatic periportal fibrosis. The eggs laid by adult parasites are trapped in the liver along the periportal tissues, a process that leads to marked inflammation, tissue eosinophilia, collagen deposition and, ultimately, fibrous expansion of the portal spaces and intrahepatic portal-vein obstruction.
Abath Immunopathogenic mechanisms in schistosomiasis: what can be learnt from human studies? Trends in parasitology 2006 vol:22 iss:2 pg:85 -91
There is a balance of mutual survival between host and infectious agents. For pathogens, this depends on the level of cell and tissue damage caused by the infectious agent and on the kinetics of infection. For hosts, survival depends on mechanisms of innate resistance and on the repertoire of T cells and B cells that are responsible for providing adaptive immunity.