Schistosomiasis continues to be a significant cause of parasitic morbidity and mortality worldwide. This review considers the basic features of the pathology and clinical outcomes of hepatointestinal and genitourinary schistosomiasis, presents an overview of the numerous studies on animal models that have clarified many of the immunopathological features, and provides insight into our current understanding of the immunopathogenesis and genetic control of human schistosomiasis. In murine schistosomiasis, pathology is induced by a CD4(+) Th2 driven granulomatous response directed against schistosome eggs lodged in the host liver. The Th2 cytokines IL-4 and IL-13 drive this response, whereas IL-10, IL13Ralpha2, IFN-gamma and a subset of regulatory T-cells act to limit schistosome induced pathology. A variety of cell types including hepatic stellate cells, alternatively activated macrophages and regulatory T-cells have also been implicated in the pathogenesis of schistosomiasis. Current knowledge suggests the immunopathogenic mechanisms underlying human schistosomiasis are likely to be similar. The review also considers the future development of anti-pathology schistosome vaccines. As fibrosis is an important feature of many other diseases such as Crohn's disease and sarcoidosis, a comprehensive understanding of the cellular and molecular mechanisms involved in schistosomiasis may also ultimately contribute to the development an effective disease intervention strategy for other granulofibrotic diseases.

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We assessed the epidemiology and morbidity related to Schistosoma japonicum infection by both parasitological (Kato-Katz method and miracidium hatching test) and ultrasound examination in a migrant fisherman community (n = 106) from the Dongting Lake region in China in 2001. A prevalence of 69.8% and a mean infection intensity of 66.5 eggs per gram (epg) were recorded for this group. Males had a higher level of infection (77%) and intensity (92.2 epg) compared with females (58% and 28.6 epg, respectively). Subjects aged 11-20 years had the highest prevalence of infection (91%) and the heaviest infection intensity (85.3 epg) among all age groups. Twenty-six percent of the subjects had not been treated previously for schistosomiasis. Parenchymal fibrosis (> or = stage II) detected by ultrasound and spleen enlargement (or splenectomy) occurred in 37% and 9% of subjects, respectively. Portal vein dilation was detected in 18% subjects, and 58% (11/19) of those patients with portal vein enlargement were shown to have parenchymal fibrosis (> or = stage II). These results indicate that S. japonicum infection and related morbidity in mobile fisherman is still unacceptably high despite the fact that China has implemented a Schistosomiasis Control Project financed by a World Bank Loan for a period of 8 years since 1992. Clearly, new approaches for schistosomiasis control, especially in communities like these mobile fishermen, should be explored.