Ultrasound in schistosomiasis--a critical look at methodological issues and potential applications

This is the concluding paper of a series on the use of diagnostic ultrasound in the investigation of schistosomiasis. An earlier chapter in the volume discussed standardization of the methodology, and of recording, when ultrasound is used for epidemiological purposes. The present paper discusses some other requirements for obtaining ultrasound data which can be used to make valid comparisons within and between studies. Since there is an inherent variability in the interpretation of results from ultrasound images, quality control and the training of observers are both essential. It is also necessary to collect more information for each endemic setting about possible concomitant diseases which might lead to misinterpretation of results. Furthermore, the analysis of the data obtained must be uniform if valid comparisons are to be made. A final section considers applications of ultrasonography in research and control programmes. The technique should make it possible to obtain a better understanding of the extent and distribution of organ damage due to schistosomal infection in different geographical areas, and of the way in which lesions develop over time, or may regress in response to treatment. Since ultrasonography will always remain a relatively labour-intensive and expensive technique, it is necessary to establish, in different settings, how its findings correlate with the results of parasitological, serological and biochemical tests. The ultimate aim is to build up a body of information on the potential of ultrasonography, in combination with other procedures, in the various possible approaches to morbidity control.