Table 1 Summary of cluster-randomised trial and non-randomised cluster intervention studies evaluating the effect of WASH interventions on soil-transmitted helminth infections
Setting | Design | Follow-up duration | Intervention and control | STH outcomes | Impact on STH |
|---|---|---|---|---|---|
School-based trials | |||||
 Peru, Belén [11] | Pair-matched cluster-randomized controlled trial in 18 schools | 4 months | Intervention: deworming followed by hygiene education which was supported by fortnightly support visits Control: deworming alone | STH infection; knowledge about STH among grade 5 school children (~12 years of age) | Intensity of A. lumbricoides 58% lower in the intervention arm but no impact on intensity of T. trichiura or hookworm; no impact on prevalence of any STH |
 China, Hunan Province [10] | Single-blind, unmatched, cluster-randomized trial in 38 urban schools | 1 school year | Intervention: Behavior change intervention, including a cartoon video Control: display of a health-education poster | A. lumbricoides and T. trichiura infection; knowledge about STH; hand-washing behavior (hookworm not present) | 50% reduction in STH infection |
 Kenya, Nyanza Province [12] | Cluster-randomized trial in 40 schools | 10 months | Intervention: deworming followed by hygiene promotion, water treatment technology and supplies, latrine construction and hand washing and drinking water storage containers Control: deworming alone | STH reinfection among school children | 44% reduction on A. lumbricoides reinfection, but no impact on other STH species |
Community-based trials | |||||
 Northern Ethiopia [24] | Individual 2 × 2 factorial clustered randomized in 216 households | 6 months | Intervention: promotion of handwashing with (provided) soap and nail clipping | STH reinfection among children aged 6–15 years | Lower rates of STH reinfection among children receiving handwashing intervention (14 vs 29%) and nail clipping (17 vs 26%) |
 India, Odisha [13] | Cluster-randomized trial in 100 rural villages | 30 months | Intervention: latrine promotion and construction, as part of a CLTS campaign | STH infection among children aged <5 years | No impact on STH infection |
 India, Madhya Pradesh [14] | Cluster-randomized trial in 80 rural villages | 21 months | Intervention: subsidies for and promotion of household latrines, as part of a CLTS campaign | STH infection among children aged <2 years | No impact on STH infection |
 Kenya, Western Province [16] | Cluster-randomized trial in 1226 villages grouped into 702 clusters | 24 months | Intervention: 6 interventions including water, sanitation, handwashing, nutrition, combined WASH, and combined WASH plus nutrition (WSHN) Control: active and passive controls (no deworming) | STH infection among children aged 2 years and an older child in each household (mainly A. lumbricoides) | A. lumbricoides infection prevalence was 18% lower in the water arm, 22% lower in the combined WASH arm, and 22% lower in the WSHN arm |
 Bangladesh [17] | Cluster-randomized trial in 5551 compounds grouped into 702 clusters | 26 months | Intervention: 6 interventions including water, sanitation, handwashing, nutrition, combined WASH, and combined WASH plus nutrition (WSHN) Control: passive controls (no deworming by study) | STH infection among children aged 2 years and up to 2 older children in each household | Water intervention reduced hookworm by 31% but did not affect other STH. Sanitation reduced T. trichiura by 29%, had a similar borderline effect on hookworm and no effect on A. lumbricoides. Combined WASH reduced hookworm by 29% and WSHN by 33% |
 Timor-Leste, Manufahi [19] | Cluster-randomized trial in 18 rural villages | 24 months after 1st deworming | Intervention: provision of water, CLTS based sanitation promotion and handwashing education, integrated with deworming of whole communities Control: deworming of whole communities | STH infection among entire communities | No additional impact of WASH interventions on STH infection compared to deworming alone |
Non-randomised studies | |||||
 Côte d’Ivoire, south-eastern [20] | Non-randomized cluster intervention study in 9 villages | 13 months | Intervention: CTS campaign and hygiene education plus two rounds of community-based deworming Control: two rounds of community-based deworming | STH infection among household members (mainly hookworm present) | No statistically significant impact on STH prevalence, potentially higher hookworm ERR in intervention |