Can prevalence of infection in school-aged children be used as an index for assessing community prevalence?

Community data on the prevalence of helminth infections is important for gu iding health policy, but expensive to collect. As a result most surveys foc us on school-aged children, frequently using schools as a sentinel populati on. Since there already exists a vast amount of data on infection levels in school-aged children, but limited community-based data, we undertook a lit erature search on age-stratified infection data for intestinal nematode inf ections and schistosomiasis in Africa, to investigate whether estimates of the prevalence of infection in school-aged children could provide an index for determining community prevalence. The observed data on prevalence of in fection in infants, school-aged children and adults were fitted using linea r and logistic regression models which take into account variation in sampl e prevalences. Despite the wide variation in study sites, the observed rela tionship between community prevalence and school-aged prevalence was remark ably consistent for each parasite species. The prevalence of infection in s chool-aged children alone was shown to be higher than the predicted prevale nce in the community, but the degree of overestimation was dependent on the parasite species and the level of infection. The results suggest that the prevalence of infection in school-aged children could provide a cost-effect ive predictive tool which can be used at a district/national level to ident ify target areas for control and to evaluate the numbers at risk of infecti on.