Evaluating the epidemiological impact of national control programmes for helminths.

During the past decade, there has been renewed commitment to programmes for helminth control, and several international initiatives have been launched. Scientific evaluation of large-scale interventions to reduce the incidence of infection and associated morbidity and mortality is vital, not only to demonstrate health benefits, but also to assess cost-effectiveness to show that monies from donor agencies have been used wisely. Using the example of schistosomiasis, this article outlines a framework for the evaluation of the impact of national control programmes, highlighting the important epidemiological and practical issues that must be addressed.