A community-based participatory research and community health workers-led health education strategy for schistosomiasis control among schoolchildren in Pemba Island, Zanzibar: a cluster-randomized trial

Abstract Background Schistosomiasis remains an intractable public health challenge in sub-Saharan Africa. While mass drug administration (MDA) has been the cornerstone of control, its limited impact on sustained behavioral change and persistent transmission in high-intensity transmission areas underscores the urgent need for complementary strategies. We aimed to evaluate the effectiveness of a community-based participatory research (CBPR) approach led by community health workers (CHWs), compared to conventional health education, in achieving sustainable schistosomiasis control among schoolchildren in Pemba, Zanzibar. Methods A pilot, cluster-randomized controlled trial (cRCT) was conducted from February 2024 to February 2025. Since the screening revealed that the infection rates in all six local schools exceeded 3%, we randomly selected two of them and randomized them 1:1 to receive either a CBPR-CHW health education (1 intervention school) or conventional health education (1 control school). A total of 650 eligible school children aged 11–13 years were initially enrolled. After screening, 602 children completed the baseline survey and were assigned to either the CBPR-CHW intervention group ( n = 278) or the control group ( n = 324). After accounting for attrition, the final analytical sample at the 12-month follow-up (T3) consisted of 540 participants. The CBPR intervention was developed through a structured process of community needs assessment and co-design culminating in six culturally adapted educational modules delivered by trained CHWs. Primary outcomes were Schistosoma haematobium infection prevalence (urine egg positivity) and comprehensive knowledge, attitudes, and practices (KAP) scores, assessed at baseline (T1), 6 months (T2), and 12 months long-term follow-up (T3). Analyses utilized two-way repeated-measures ANOVA with Bonferroni correction for KAP score comparisons, supplemented by Kruskal–Wallis tests for non-normal data. Missing values (< 5%) were addressed via multiple imputation. Results Loss to follow-up was low across all time points, ranging from 8.5 to 11.9%. At the 12-month follow-up (T3), the CBPR-CHW group demonstrated a significantly greater reduction in infection prevalence (from 19.18 to 0.82%) ( P < 0.001) compared to the control group (from 11.86 to 1.02%). The CBPR-CHW group also showed sustained, significant improvements in KAP scores, significantly outperforming the control group at T3 (e.g., knowledge scores: 7.11 ± 1.35 vs. 6.56 ± 1.70; P < 0.05). In contrast, the control group showed transient or non-significant improvements. High student satisfaction was reported (total score: 5.28 ± 1.28/6), and household latrine usage increased by 56.3%. Conclusions The CBPR-CHWs-led strategy was significantly more effective than conventional education in achieving sustainable reductions in schistosomiasis infection and improvements in KAP outcomes. This model represents a highly effective, scalable complement to MDA, directly addressing gaps in the WHO’s 2030 elimination roadmap by fostering community ownership and cultural relevance. Trial registration : ClinicalTrials.gov NCT06312462. Registered on February 28, 2024. Available at: https://register.clinicaltrials.gov/