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Abstract：
Quantitative polymerase chain reaction (qPCR) is gaining recognition in soil-transmitted helminth (STH) diagnostics, especially for Strongyloides stercoralis and differentiating hookworm species. However, sample preservation and DNA extraction may influence qPCR performance. We estimated STH prevalence and infection intensity by using qPCR in schoolchildren from Huambo, Uige, and Zaire, Angola, and compared its performance with that of the Kato-Katz technique (here termed Kato-Katz). Stool samples from 3,063 children (219 schools) were preserved in 96% ethanol and analyzed by qPCR, of which 2,974 children (215 schools) had corresponding Kato-Katz results. Cluster-adjusted prevalence and infection intensity estimates were calculated by qPCR and Kato-Katz, with cycle threshold values converted to eggs per gram for qPCR. Cohen\'s kappa statistic evaluated agreement between qPCR and Kato-Katz. DNA extraction and qPCR were repeated on 191 (of 278) samples that were initially qPCR negative but Kato-Katz positive, of which 112 (58.6%) became positive. Similar prevalence for Ascaris lumbricoides (37.5% versus 34.6%) and Trichuris trichiura (6.5% versus 6.1%) were found by qPCR and Kato-Katz, respectively, while qPCR detected a higher hookworm prevalence (11.9% versus 2.9%). The prevalence of moderate- or high-intensity infections was higher by Kato-Katz than by qPCR. Agreement between qPCR and Kato-Katz was very good for A. lumbricoides, moderate for T. trichiura, and fair for hookworm. Strongyloides stercoralis prevalence was 4.7% (municipality range, 0-14.3%), and no Ancylostoma ceylanicum was detected by qPCR. Despite suboptimal performance, presumably due to fixative choice, qPCR was fundamental in detecting S. stercoralis and excluding zoonotic A. ceylanicum. Further evaluations on sample fixatives and DNA extraction methods are needed to optimize and standardize the performance of qPCR.
摘要：
定量聚合酶链反应（qPCR）在土壤传播的蠕虫（STH）诊断中获得认可，特别是对于赤圆圆线虫和鉴别钩虫种类。然而,样品保存和DNA提取可能会影响qPCR性能。我们通过使用qPCR在万博的学童中估计了STH的患病率和感染强度，Uige,还有扎伊尔,安哥拉,并将其性能与Kato-Katz技术（这里称为Kato-Katz）进行了比较。将3,063名儿童（219所学校）的粪便样本保存在96％的乙醇中，并通过qPCR进行分析。其中2,974名儿童（215所学校）有相应的加藤-卡茨成绩。通过qPCR和Kato-Katz计算集群调整的患病率和感染强度估计值，与循环阈值转换为每克鸡蛋qPCR。科恩的卡帕统计数据评估了qPCR和卡托-卡茨之间的一致性。对最初qPCR阴性但Kato-Katz阳性的191个（278个）样品重复DNA提取和qPCR，其中112人（58.6%）为阳性。通过qPCR和Kato-Katz发现，A虫的患病率相似（37.5％对34.6％）和Trichuris（6.5％对6.1％），分别,而qPCR检测到更高的钩虫患病率(11.9%对2.9%)。Kato-Katz的中度或高强度感染患病率高于qPCR。qPCR和Kato-Katz之间的协议对A.lumbricoides非常好，对于T.trichiura来说是适度的，对钩虫来说是公平的。胸圆圆线虫的患病率为4.7%(市政范围，0-14.3%），qPCR未检测到cycyloma。尽管性能欠佳，大概是由于固定剂的选择，qPCR是检测赤霉病和排除人畜共患头孢霉素的基础。需要对样品固定剂和DNA提取方法进行进一步评估以优化和标准化qPCR的性能。
