Table_1_Prevalence and Correlation Analysis of Soil-Transmitted Helminths Infections and Treatment Coverage for Preschool and School Aged Children in Kenya: Secondary Analysis of the National School Based Deworming Program Data.DOCX

Background: Soil-transmitted helminths (STH) are among the most common parasitic infections globally, disproportionately affecting children. Treatment of STH in Kenya is often targeted at preschool (PSAC) and school aged (SAC) children delivered through annual mass drug administration (MDA) in primary schools. Understanding group-specific prevalence and dynamics between treatment and coverage is critical for continued treatment success. This study aims to provide detailed information on group-specific infection prevalence and relative reductions (RR), and their relationships with treatment coverage over time. Additionally, it aims to quantify the correlation between the observed school level infection prevalence and treatment coverage.
Methods: Secondary analysis of existing data collected between 2012 and 2018 by the monitoring and evaluation (M&E) program of the National School-Based Deworming (NSBD) program was used. The M&E program conducted surveys utilizing cross-sectional study design, at four survey time points, in a nationally-representative sample of schoolchildren across counties in Kenya. In each participating school, the program randomly sampled 108 children per school, of both groups. Infection prevalence was estimated using binomial regression, RR in prevalence using multivariable mixed effects model, statistical correlations using structural equation modeling, and change-point-analysis using the binary segmentation algorithm.
Results: Overall, STH prevalence for PSAC was 33.7, 20.2, 19.0, and 17.9% during Year 1 (Y1), Year 3 (Y3), Year 5 (Y5), and Year 6 (Y6) surveys, respectively with an overall RR of 46.9% (p = 0.001) from Y1 to Y6. Similarly, overall STH prevalence for SAC was 33.6, 18.4, 14.7, and 12.5% during Y1, Y3, Y5, and Y6 surveys, respectively with an overall RR of 62.6% (p < 0.001). An overall (all time points) significant but very weak negative correlation was found between treatment coverage and undifferentiated STH prevalence (r = −0.144, p = 0.002) among PSAC but not in SAC. Further, we observed inter-county heterogeneity variation in infection prevalence, RR, as well as correlations.
Conclusion: The analysis showed that after six rounds of MDA, prevalence of STH has significantly declined among both groups of children, however not to a point where it is not a public health problem (below 1%). The analysis, additionally established an overall significant but weak negative correlation between treatment coverage and prevalence, indicating that the current treatment coverage might not be sufficient to drive the overall STH prevalence to below 1%. These findings will allow STH control programs in Kenya to make decisions that will accelerate the attainment of STH elimination as a public health problem.

背景：土壤传播性蠕虫（Soil-transmitted helminths, STH）是全球最常见的寄生虫感染性疾病之一，对儿童群体的影响尤为突出。在肯尼亚，土传蠕虫感染的治疗通常针对学龄前儿童（preschool children, PSAC）与学龄儿童（school-aged children, SAC），通过小学开展的年度集体药物分发（mass drug administration, MDA）项目实施。明确不同群体的感染流行率、治疗与覆盖情况间的动态关联，对维持治疗成效至关重要。本研究旨在详细阐明不同群体的感染流行率、相对降幅（relative reductions, RR）及其随时间变化与治疗覆盖率的相关性；此外还将量化学校层面观测到的感染流行率与治疗覆盖率之间的关联强度。

方法：本研究对肯尼亚国家学校驱虫项目（National School-Based Deworming, NSBD）的监测与评价（monitoring and evaluation, M&E）项目在2012年至2018年间收集的现有数据进行二次分析。该监测与评价项目采用横断面研究设计，在肯尼亚各县的全国代表性学龄儿童样本中开展了4次调查。每所参与学校按两类群体随机抽取108名儿童。感染流行率通过二项回归模型估算，流行率相对降幅采用多变量混合效应模型计算，统计相关性通过结构方程模型分析，并使用二元分割算法开展变点分析。

结果：整体而言，学龄前儿童的土传蠕虫感染流行率在第1年（Y1）、第3年（Y3）、第5年（Y5）及第6年（Y6）的调查中分别为33.7%、20.2%、19.0%和17.9%，从Y1至Y6的总体相对降幅为46.9%（p=0.001）。同理，学龄儿童的整体流行率在对应调查年份分别为33.6%、18.4%、14.7%和12.5%，总体相对降幅达62.6%（p<0.001）。在所有调查时间点中，学龄前儿童的治疗覆盖率与未分型土传蠕虫感染流行率之间存在显著但极弱的负相关（r=-0.144, p=0.002），而学龄儿童未观察到此关联。此外，研究发现不同县域间的感染流行率、相对降幅及相关性存在异质性差异。

结论：本分析显示，在完成6轮集体药物分发后，两类儿童群体的土传蠕虫感染流行率均出现显著下降，但仍未降至可归类为非公共卫生问题的水平（即低于1%）。此外，分析证实治疗覆盖率与感染流行率之间存在总体显著但较弱的负相关，表明当前的治疗覆盖率或许不足以将整体土传蠕虫感染流行率降至1%以下。上述研究结果将助力肯尼亚土传蠕虫感染防控项目制定决策，以加速实现将土传蠕虫感染作为公共卫生问题予以消除的目标。