Ultrasound in schistosomiasis : a practical guide to the standard use of ultrasonography for assessment of schistosomiasis-related morbidity

Overview

The aim of schistosomiasis control programmes is to reduce morbidity. However, most of the widely-used methods for assessing the success of interventions use parameters like egg-counts, which measure the level of infection but do not provide direct evidence about pathological changes. The planning of interventions so that they are effective in reducing damage to internal organs requires knowledge of what changes occur, how fast and how far they can be reversed by treatment, and how soon they appear again after reinfection. Ultrasonography is an excellent way of obtaining such information, not only in the hospital setting but in surveys at the community level, and it has been used for this purpose in many endemic areas. However, if these data are to be used to build up an overall picture on a world-wide scale that can be used as a basis for planning control programmes, it is necessary to have results that can be reliably compared. This is not always possible at present, because different investigators have selected different examination techniques and measurements out of the wide range of possibilities available.

One solution to the problem of obtaining comparable data from different ultrasound studies is the use of standardized protocols for examination and reporting. The first step towards developing such protocols was taken in Cairo in 1990. At a workshop sponsored by WHO/TDR and the Swiss Tropical Institute, scientists, clinicians and control officers discussed their experience of using ultrasound in schistosomiasis, especially in surveys and field studies. They identified areas where more research was needed, and proposed a set of standardized examinations and reporting procedures. The results were published in detail in a review (Cairo Working Group 1992), and a White Paper Report with detailed practical instructions (WHO 1991).