The impact of ivermectin, diethylcarbamazine citrate, and albendazole mass drug administration on the prevalence of scabies and soil-transmitted helminths in school-aged children in three municipalities in Timor-Leste: a before-after assessment

Background Integrated programmes that use combination mass drug administration (MDA) might improve control of multiple neglected tropical diseases simultaneously. We investigated the impact of Timor-Leste's national ivermectin, diethylcarbamazine citrate, and albendazole MDA, for lymphatic filariasis elimination and soil-transmitted helminth (STH) control, on scabies, impetigo, and STH infections. Methods We did a before-after study in six primary schools across three municipalities in Timor-Leste (urban [Dili], semi-urban [Ermera], and rural [Manufahi]) before (April 23 to May 11, 2019) and 18 months after (Nov 9 to Nov 27, 2020) MDA delivery between May 17 and June 1, 2019. Study participants included schoolchildren, as well as infants, children, and adolescents who were incidentally present at school on study days. All schoolchildren whose parents provided consent were eligible to participate in the study. Infants, children, and adolescents younger than 19 years who were not enrolled in the school but were incidentally present at schools on study days were also eligible to participate if their parents consented. Ivermectin, diethylcarbamazine citrate, and albendazole MDA was implemented nationally, with single doses of oral ivermectin (200 mu g/kg), diethylcarbamazine citrate (6 mg/kg), and albendazole (400 mg) administered by the Ministry of Health. Scabies and impetigo were assessed by clinical skin examinations, and STHs using quantitative PCR. The primary (cluster-level) analysis adjusted for clustering while the secondary (individual-level) analysis adjusted for sex, age, and clustering. The primary outcomes of the study were prevalence ratios for scabies, impetigo, and STHs (Trichuris trichiura, Ascaris lumbricoides, Necator americanus, and moderate-to-heavy A lumbricoides infections) between baseline and 18 months from the cluster-level analysis. Findings At baseline, 1043 (87.7%) of 1190 children registered for the study underwent clinical assessment for scabies and impetigo. The mean age of those who completed skin examinations was 9.4 years (SD 2.4) and 514 (53.8%) of 956 were female (87 participants with missing sex data were excluded from this percentage calculation). Stool samples were received for 541 (45.5%) of 1190 children. The mean age of those for whom stool samples were received was 9.8 years (SD 2.2) and 300 (55.5%) were female. At baseline, 348 (33.4%) of 1043 participants had scabies, and 18 months after MDA, 133 (11.1%) of 1196 participants had scabies (prevalence ratio 0.38, 95% CI 0.18- 0.88; p=0.020) in the cluster-level analysis. At baseline, 130 (12.5%) of 1043 participants had impetigo, compared with 27 (2.3%) of 1196 participants at follow-up (prevalence ratio 0 .14, 95% CI 0 .07-0.27; p<0.0001). There was a significant reduction in T trichiura prevalence from baseline (26 [4.8%] of 541 participants) to 18-month follow-up (four [0.6%] of 623 participants; prevalence ratio 0.16, 95% CI 0.04-0.66; p<0.0001). In the individual- level analysis, moderate-to-heavy A lumbricoides infections reduced from 54 (10.0%; 95% CI 0.7-19.6) of 541 participants to 28 (4.5%, 1.2- 8.4) of 623 participants (relative reduction 53.6%; 95% CI 9 .1-98.1; p=0.018). Interpretation Ivermectin, diethylcarbamazine citrate, and albendazole MDA was associated with substantial reductions in prevalence of scabies, impetigo, and T trichiura, and of moderate-to-heavy intensity A lumbricoides infections. Combination MDA could be used to support integrated control programmes to target multiple NTDs. Copyright (c) 2023 The Author(s). Published by Elsevier Ltd.