Evaluation of public health impact of schistosomiasis.

Present knowledge on the "importance"/"impact" of schistosomiasis is reviewed. Due to different methological approaches and outcome measures used as well as the substantial inter- and intra-setting variation of the epidemiology, the public health importance of schistosomiasis appears quite inconclusive for any schistosome species and cannot be generalised. In most studies "importance" is mainly understood as the amount of schistosome-related morbidity and mortality. The consequence of these morbidity patterns are however hardly specified in terms of impact on (i) the physical and socioeconomic development of an affected family/household and on (ii) the economic and social consequences for community development. It follows that impact studies mainly considered individuals as unit of analysis and hardly focused on the family/household-level. Consequently, microeconomic studies were so far not undertaken within the concept of household production models and did not distinguish between market and non-market productivity. Standardized ranking of measured schistosome-related morbidity combined with perception patterns of disease, signs, symptoms and of additional health and community development issues could lead to new approaches on how epidemiological data on the transmission and morbidity of schistosomiasis could be linked with information on health and development priorities of a community in order to estimate the relative impact of the disease.