Applications and outcomes of periodic epidemiological surveys for schistosomiasis and related economic evaluation in the People's Republic of China.

The great success in schistosomiasis control in China is attributable to a range of factors. Periodic epidemiological surveys (PES) used for monitoring and adapting control interventions over time are an integral feature of the national schistosomiasis control programme. PES have enabled the dynamic trends of schistosomiasis epidemics to be closely pursued and have assisted in analysing subtle changes in endemicity. The results can be summarised mathematically allowing the variation in efficacy of control measures to be readily determined and enabling control strategies to be adjusted and updated. PES have been used in both cross-sectional and longitudinal pilot studies selected by appropriate sampling methods. In the early 1990s, when the World Bank Loan Project for schistosomiasis control commenced, economic evaluations were initiated in parallel. Cost-effectiveness analysis became a necessary tool to identify the most financially feasible yet effective options among a range of alternative control strategies. There was, however, a lack of standardised approaches rendering study comparisons across sites difficult. The global burden of disease study established the disability adjusted life year (DALY) as a measure of population health, combining in a single indicator years lost from premature death and years of life lived with disability. However, a recent meta-analysis reveals that the burden of schistosomiasis is underestimated, and hence, needs to be revised. It is envisaged that after the revision of DALYs lost due to schistosomiasis japonica, they will become an essential measure in future schistosomiasis control assessments in China and in other schistosome-endemic areas of the world.