GSTM1 and helminthiasis: In addition, data collected from 374 (10.0%) school children were dropped from the final data set as their records were incomplete or they were > 19 years old, resulting in 1073 complete cases for the assessment of prevalence and intensity of helminth infections, and Hb concentration (592 in the control arm and 481 in the intervention arm), 24 complete schools (12 in the control arm and 12 in the intervention arm) for the school WASH questionnaire and 209 (of the 596 recruited subjects) for the student WASH-KAP questionnaire.