[Ultrasonoic diagnosis of morbidity related to schistosomiasis due to Schistosoma mansoni and Schistosoma haematobium: epidemiological and individual value].

By allowing study of large population samples, ultrasonography has revolutionized assessment of schistosomiasis-related morbidity. Previous clinical or parasitological parameters provided poor documentation of the public health impact of schistosomiasis. Thanks to a WHO-coordinated drive to standardize examination protocols and severity scores, comparison of data from different regions is now much easier. The latest "Niamey" methodology has eliminated the major shortcomings of earlier methods. Detection of periportal fibrosis is the cardinal diagnostic feature for Schistosoma mansoni. Ultrasonographic evidence has been validated by correlation with hepatic biopsy findings from hospitalized patients with severe disease. The specificity of ultrasonography is poor in low- or moderate-grade disease for which different methodologies give discordant results. Ultrasonography is highly sensitive for assessment of morbidity related to Schistosoma haematobium infection, which is associated with typical bladder lesions. Lesions involving the upper urinary tract are also well visualized but do not constitute a specific finding. The best applications for which ultrasonographic investigation of schistomsomiasis is now considered as mandatory are community-based studies and post-therapeutic follow-up of populations. In contrast ultrasonography is not well suited to individual diagnosis. In endemic areas, ultrasonography may be used for individual diagnosis if more effective methods are unavailable. However the poor specificity of some images is a major limitation for use in zones of low transmission.