An impact evaluation of two rounds of mass drug administration on the prevalence of active trachoma: A clustered cross sectional survey

IntroductionWe investigated the impact of two round of mass drug administration on trachoma prevalence in Plateau and Nasarawa States of Nigeria. The mass drug administration was conducted as a component of the SAFE Strategy, a combination of interventions recommended for the global elimination of blinding trachoma.MethodsThe study consisted of a two-stage cross-sectional clustered sample survey in which 3990 people from 793 households were screened for clinical signs of trachoma.ResultsOf the total 3990 people examined, 1530 were children, of which 808 (53%) were boys and 704 (47%) were girls. The impact of intervention as measured by the changes in overall prevalence of follicular trachoma were as follows: At baseline the overall prevalence of follicular trachoma among children 1–9 years of age was 6.4%, 95% CI [5.8, 7.0]; the overall prevalence of trachomatous trichiasis in the total population was 0.20%, 95% CI [0.16, 0.25]. At follow up, the overall prevalence of follicular trachoma among children 1–9 years of age was 3.4%, 95% CI [1.9, 4.9]; the overall prevalence of trachomatous trichiasis in the total population was 0.20%, 95% CI [0.00, 0.05]. The highest statistically significant reduction (96%) in follicular trachoma prevalence was observed in Doma Local Government Area of Nasarawa State from baseline prevalence of 13.6%, 95% CI [9.7, 17.5] to follow-up prevalence of 0.5%, 95% CI [0.0, 1.5] and the lowest reduction (58%) in follicular trachoma prevalence was observed in Langtang North Local Government Area of Plateau State from baseline prevalence of 15.8%, 95% CI [9.3, 22.3] to 6.6%, 95% CI [1.6, 11.6], (pConclusionA significant reduction in the overall prevalence of follicular trachoma was achieved after two rounds of mass drug administration. In the absence of significant activities pertaining to facial cleanliness and environmental sanitation components of the SAFE strategy in the intervention areas, the observed deep reductions in prevalence could mainly be attributed to mass drug administration. Therefore, two rounds of mass azithromycin administration may be as effective as guideline-recommended three or more rounds in reducing active trachoma prevalence but findings should be replicated in more robustly designed studies.

**引言** 本研究旨在评估两轮大规模药物给药（mass drug administration, MDA）对尼日利亚高原州（Plateau State）与纳萨拉瓦州（Nasarawa State）沙眼患病率的影响。本次大规模药物给药作为SAFE策略（SAFE Strategy）的组成部分实施，该策略是全球推荐用于消除致盲性沙眼的联合干预方案。

**方法** 本研究采用两阶段横断面整群抽样调查设计，对来自793户家庭的3990名受试者进行沙眼临床体征筛查。

**结果** 在全部3990名受检者中，1530名为儿童，其中男童808名（占比53%），女童704名（占比47%）。以滤泡性沙眼（follicular trachoma）总体患病率变化衡量的干预效果如下：基线时，1~9岁儿童群体的滤泡性沙眼总体患病率为6.4%，95%置信区间（confidence interval, CI）[5.8, 7.0]；全人群的沙眼性倒睫（trachomatous trichiasis）患病率为0.20%，95% CI [0.16, 0.25]。随访阶段，1~9岁儿童群体的滤泡性沙眼总体患病率降至3.4%，95% CI [1.9, 4.9]；全人群的沙眼性倒睫患病率为0.20%，95% CI [0.00, 0.05]。纳萨拉瓦州多马地方政府区（Doma Local Government Area）的滤泡性沙眼患病率降幅最高（96%），且具有统计学意义，其基线患病率为13.6%，95% CI [9.7, 17.5]，随访时降至0.5%，95% CI [0.0, 1.5]；而高原州朗唐北地方政府区（Langtang North Local Government Area）的滤泡性沙眼患病率降幅最低（58%），基线患病率为15.8%，95% CI [9.3, 22.3]，随访时为6.6%，95% CI [1.6, 11.6]，（*p*

**结论** 经两轮大规模药物给药后，滤泡性沙眼的总体患病率显著降低。由于干预区域未开展SAFE策略中面部清洁与环境卫生相关的实质性工作，本次观测到的患病率大幅下降主要可归因于大规模药物给药。由此可见，两轮阿奇霉素（azithromycin）大规模给药在降低活动性沙眼患病率方面，效果或与指南推荐的三轮及以上给药方案相当。