Assessment of the programmatic effectiveness of single-dose albendazole against soil-transmitted helminthiasis in school-age children following seven rounds of annual mass drug administration in selected counties of Kenya

Background Soil-transmitted helminthiasis infections are targeted for elimination as a public health problem by 2030 under the Kenya Master Plan for neglected tropical diseases (2023-2027) and the Kenya health policy (2014-2030). Preventive chemotherapy via mass drug administration remains the primary control strategy. This study aimed to determine the programmatic effectiveness of albendazole among school-age children attending primary schools in Kisii, Narok, and Vihiga Counties that have participated in the National School-Based Deworming Programme since 2012. Methods A prospective longitudinal study comprising repeated cross-sectional surveys was conducted between March and July 2019. Counties were purposively selected based on sustained high infection prevalence (>30%) or low relative reduction in prevalence (<50%) in the 2018 national evaluation survey. Primary schools with historical prevalence exceeding 30% were sampled, and children were screened using the Kato-Katz technique at baseline. Baseline-positive children (n = 573) were enrolled and monitored across three sequential post-treatment follow-up rounds. Cure rates and egg reduction rates were evaluated against baseline using weighted Poisson regression models with robust variance estimation, with non-linear parameter transformations and 95% confidence intervals derived using delta method. Results At Follow-up 1, albendazole demonstrated high effectiveness against Ascaris lumbricoides, achieving a cure rate of 94.80% (95% CI: 92.61-97.00%) and an egg reduction rate of 95.54% (95% CI: 92.36-98.71%), surpassing the World Health Organization performance benchmark (>=95%). For Trichuris trichiura, the cure rate was 65.41% (95% CI: 56.49-74.34%) and an egg reduction rate of 53.79% (95% CI: 15.95-91.62%), with lower egg reductions observed in specific subgroups. For hookworm, initial cure rate was 76.74% (95% CI: 26.84-126.63%) and egg reduction rate was 99.40% (95% CI: 97.89-100.90%). Over subsequent monitoring, cure and egg reduction rates fluctuated, reflecting local environmental re-exposure and transmission dynamics. Conclusions Single-dose albendazole demonstrated high initial effectiveness against Ascaris lumbricoides at the first follow-up, meeting the (>=95%) World Health Organization egg reduction threshold. However, observed treatment effectiveness fluctuated across subsequent survey rounds without re-treatment, and Trichuris trichiura exhibited a sub-optimal response with subgroup variations that failed to meet threshold. Overall, while single-dose albendazole maintains robust effectiveness against roundworm, its localized programmatic effectiveness against whipworm remains limited in these persistent transmission foci.