A longitudinal cohort study of soil-transmitted helminth infections during the second year of life and associations with reduced long-term cognitive and verbal abilities

BackgroundSoil-transmitted helminth (STH) infection leads to malnutrition and anemia, and has been linked to impaired child development. Previous research on this topic is limited and mostly conducted in school-age children. The goal of this study was to determine the effect of the number of detected STH infections between one and two years of age on subsequent cognitive and verbal abilities, in a cohort of preschool children.Methodology/Principal findingsA longitudinal cohort study was conducted in 880 children in Iquitos, Peru between September 2011 and July 2016. Children were recruited at one year of age and followed up at 18 months and then annually between two and five years of age. STH infection was measured with the Kato-Katz technique or the direct smear technique. Child development was measured with the Bayley Scales of Infant and Toddler Development-III at the one to three-year visits and with the Wechsler Preschool and Primary Scale of Intelligence-III at the four and five-year visits. Hierarchical multivariable linear regression models were used to account for the repeated outcome measures for each child and Bayesian latent class analysis was used to adjust for STH misclassification. Children found infected with any STH infection between one and two years of age had lower cognitive scores between two and five years of age (between group score differences (95% credible intervals) for infected once, and infected two or three times, compared to never infected: -4.31 (-10.64, -0.14) and -3.70 (-10.11, -0.11), respectively). Similar results were found for Ascaris infection and for verbal scores.Conclusions/SignificanceAn association was found between having been infected with Ascaris or any STH between one and two years of age and lower cognitive and verbal abilities later in childhood. These results suggest that targeting children for STH control as of one year of age is particularly important.背景 土壤传播蠕虫（Soil-transmitted helminth, STH）感染可引发营养不良与贫血，且与儿童发育受损密切相关。目前该领域的研究较为有限，且多数研究仅聚焦于学龄儿童。本研究旨在针对学龄前儿童队列，探究1至2岁期间检出的土壤传播蠕虫感染次数对其后续认知与语言能力的影响。 方法学/主要研究结果 本研究于2011年9月至2016年7月在秘鲁伊基托斯开展一项纵向队列研究，共纳入880名儿童。研究对象于1岁时入组，分别在18月龄时完成首次随访，并于2至5岁期间每年进行一次随访。采用加藤-Katz法（Kato-Katz technique）或直接涂片法检测土壤传播蠕虫感染情况。儿童发育水平的评估工具如下：1至3岁随访时使用《贝利婴幼儿发育量表第三版（Bayley Scales of Infant and Toddler Development-III）》，4至5岁随访时使用《韦克斯勒学前儿童智力量表第三版（Wechsler Preschool and Primary Scale of Intelligence-III）》。本研究采用分层多变量线性回归模型处理每名儿童的重复结局指标，并通过贝叶斯潜类别分析（Bayesian latent class analysis）校正土壤传播蠕虫感染的分类偏倚。结果显示，1至2岁期间检出任一土壤传播蠕虫感染的儿童，其2至5岁期间的认知评分更低；与未感染组相比，感染1次组、感染2或3次组的组间评分差值（95%可信区间）分别为-4.31（-10.64, -0.14）与-3.70（-10.11, -0.11）。蛔虫（Ascaris）感染组及语言评分组均得到相似结果。 结论与意义 本研究发现，1至2岁期间感染蛔虫或任一土壤传播蠕虫，与儿童后续更低的认知及语言能力存在显著关联。上述结果提示，从1岁起即针对儿童开展土壤传播蠕虫感染防控工作具有重要的公共卫生价值。