In 1998, a local non-governmental organization (NGO) launched a program known as the Primary School Deworming Program (PSDP) to provide deworming medication to individuals enrolled in 75 primary schools in Busia District, a densely-settled farming region of rural western Kenya adjacent to Lake Victoria. The schools participating in the program consisted of nearly all rural primary schools in Budalangi and Funyula divisions in southern Busia district, and contained more than 30,000 pupils at the start of the study. Baseline parasitological surveys conducted by the Kenyan Ministry of Health indicated that these divisions had high rates of helminth infection at over 90%. Using modified WHO infection thresholds (Brooker et al., 2000b), roughly one-third of children in the sample had “moderate to heavy” infections with at least one helminth at the time of the baseline survey, a rate not atypical by regional standards (Brooker et al., 2000a). The 1998 Kenya DHS indicated that 85% of children in western Kenya, in the relevant age range of 8-18 years, were enrolled in school – suggesting that the sample was broadly representative of western Kenyan children as a whole at the time.
The 75 program schools were randomly divided into three groups (Groups 1, 2, and 3) of 25 schools each: the schools were stratified by geographical area (division, then zone), the zones were listed alphabetically (within each division), and then within each zone the schools were listed in increasing order of student enrolment, and every third school was assigned to a given project group. Due to the NGO’s administrative and financial constraints, the schools were phased into the program over the course of 1998-2001, and the order of phase-in was randomly determined, creating experimental treatment groups. Group 1 schools began receiving free deworming in 1998, Group 2 schools in 1999, while Group 3 schools began receiving the drugs in 2001. The project design implies that in 1998, Group 1 schools were treatment schools while Group 2 and 3 schools were the control, and in 1999 and 2000, Group 1 and 2 schools were the treatment schools and Group 3 schools the control, and so on. In 2002 all schools received free treatment. Children in Group 1 and 2 schools thus received two to three more years of deworming than Group 3 children. Deworming drugs were offered twice per year in treatment schools.
This study uses the Primary School Deworming Project (PSDP) to test several interventions including the following: social links, cost-sharing, health education, and verbal commitment.
Social links: Parent questionnaire respondents were asked for information on their closest social links: the five friends they speak with most frequently, the five relatives they speak with most frequently, additional social contacts whose children attend local primary schools, and individuals with whom they speak specifically about child health issues. These individuals are collectively referred to as the respondent’s direct “social links.” The survey also collected information on the deworming treatment status of social links’ children and the effects of treatment on their health, how frequently the respondent speaks with each social link, which primary schools links’ children attend, the global positioning system (GPS) location of the respondent’s home, and respondent’s knowledge of worm infections and attitudes toward deworming.
Cost-sharing: Between 1998 and 1999 PSDP delivered free deworming pills to 50 sample schools. In 2001, they were randomized again to assign half the schools to a cost-sharing intervention while the other half continued to receive free treatment. Two thirds of the schools participating in cost-sharing received albendazole at a cost of USD $0.40 per family, and one third received both albendazole and praziquantel (depending on the local prevalence of schistosomiasis) at a cost of USD $1.30 per family.
Health education: In addition to medication, all treatment schools received regular public health lectures, wall charts on worm prevention, and a full-day training session for two teachers from each school. The lectures and teacher training provided information on worm prevention behaviors—including washing hands before meals, wearing shoes, and not swimming in the lake.
Verbal commitment: A random subsample of pupils were asked whether they were planning to come to school on the next treatment day and whether the PSDP workers should bring pills for them on that day: 98 percent of children answered “yes” to both questions. All pupils interviewed—including both those offered the opportunity for verbal commitment and those not offered this opportunity—were provided the same information on the effects of deworming and the upcoming date of medical treatment.