Deworming and geographical targeting
Geographical targeting is required to ensure that programmes are implemented appropriately, focusing resources for STH and schistosomiasis on areas of greatest need. The need for mass treatment is determined by the prevalence of infection in school-aged children as assessed by surveys of stool or urine samples. WHO recommend thresholds for prevalence of infection with STH and schistosomes above which deworming targeted at school-aged children is warranted.
For LF, either community or school surveys are conducted to determine whether prevalence exceeds a designated threshold above which mass drug administration of entire communities is undertaken.