International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
School of Engineering, Tufts University, Medford, MA, United States of America.
PLoS One. 2019 Sep 10;14(9):e0222355. doi: 10.1371/journal.pone.0222355. eCollection 2019.
Hands are a route of transmission for fecal-oral pathogens. This analysis aimed to assess associations between hand E. coli contamination and child age and determine if observed hand cleanliness can serve as a proxy for E. coli contamination on young children's hands.
Trained field workers collected hand rinse samples from children aged 1-14 months in 584 households in rural Bangladesh and assessed the visual cleanliness of child hands (fingernails, finger pads and palms). Samples were analyzed using the IDEXX most probable number (MPN) methodto enumerate E. coli. We assessed if child age (immobile children aged 1-4 months vs. mobile children aged 5-14 months) is associated with log10 E. coli counts on hands using generalized estimating equations (GEE). We estimated the log10 difference in hand E. coli counts associated with the cleanliness of different hand parts using a multivariable GEE model.We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for dirty fingernails, fingerpads, palms and overall hands (the three observed parts combined) against binary E. coli presence on hands.
E. coli was detected on 43% of child hands. Children in the mobile age range had 0.17 log10 MPN higher E. coli on hands than those in the immobile age range (Δlog10 = 0.17, 95% CI = 0.02, 0.32, p = 0.03). Children with visible dirt particles on finger pads had 0.46 log10 MPN higher E. coli on hands than those with clean finger pads (Δlog10 = 0.46, 95% CI = 0.05, 0.87, p = 0.03). Dirty fingernails indicated binary E. coli presence with 81% sensitivity and 26% specificity while dirty fingerpads and palms indicated E. coli presence with 29% sensitivity and 75-77% specificity. The PPV was 45-48% and NPV 59-65% for all three types of observations.
Hand contamination with E. coli was prevalent among young children in rural Bangladesh, with higher levels of contamination among mobile children. Studies should assess if strategies to remove animal feces from the courtyard, provide designated hygienic play spaces for children and deliver targeted messaging to mothers to wipe or wash children's hands after contact with animals and animal feces reduce child hand contamination. Visible hand cleanliness was a poor predictor of E. coli presence on young children's hands so other low-cost field measurements are needed to accurately detect fecal contamination on hands.
手是粪口病原体的传播途径。本分析旨在评估儿童手部大肠杆菌污染与年龄的相关性，并确定观察到的手部清洁度是否可以作为儿童手部大肠杆菌污染的替代指标。
在孟加拉国农村的 584 户家庭中，经过培训的现场工作人员收集了 1-14 个月大的儿童的手部冲洗样本，并评估了儿童手部的视觉清洁度（指甲、指垫和手掌）。使用 IDEXX 最可能数（MPN）法对样本进行分析，以对大肠杆菌进行计数。我们使用广义估计方程（GEE）评估儿童年龄（1-4 个月的不动儿童与 5-14 个月的移动儿童）与手部大肠杆菌计数之间的相关性。我们使用多变量 GEE 模型估计不同手部部位清洁度与手部大肠杆菌计数之间的对数差异。我们计算了脏指甲、指垫、手掌和整个手部（三个观察部位的组合）对双手大肠杆菌存在的敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）。
43%的儿童手部检测到大肠杆菌。处于移动年龄段的儿童手部大肠杆菌数量比处于静止年龄段的儿童高 0.17 个对数 MPN（Δlog10 = 0.17，95%CI = 0.02，0.32，p = 0.03）。手指垫有可见污垢颗粒的儿童手部大肠杆菌数量比手指垫清洁的儿童高 0.46 个对数 MPN（Δlog10 = 0.46，95%CI = 0.05，0.87，p = 0.03）。脏指甲指示大肠杆菌存在的敏感性为 81%，特异性为 26%，而脏指垫和手掌指示大肠杆菌存在的敏感性为 29%，特异性为 75-77%。所有三种观察结果的 PPV 为 45-48%，NPV 为 59-65%。
在孟加拉国农村地区，幼儿手部大肠杆菌污染普遍存在，移动儿童的污染水平较高。研究应评估从庭院中清除动物粪便、为儿童提供指定的卫生游戏空间以及向母亲传达在接触动物和动物粪便后擦拭或清洗儿童手部的信息等策略是否可以减少儿童手部的大肠杆菌污染。肉眼可见的手部清洁度是儿童手部大肠杆菌存在的不良预测指标，因此需要其他低成本的现场测量方法来准确检测手部的粪便污染。
