Table_2_Assessment of the accuracy of 11 different diagnostic tests for the detection of Schistosomiasis mansoni in individuals from a Brazilian area of low endemicity using latent class analysis.XLSX

BackgroundSchistosomiasis is a parasitic disease associated with poverty. It is estimated that 7.1 million people are infected with Schistosoma mansoni in Latin America, with 95% of them living in Brazil. Accurate diagnosis and timely treatment are important measures to control and eliminate schistosomiasis, but diagnostic improvements are needed to detect infections, especially in areas of low endemicity.
MethodologyThis research aimed to evaluate the performance of 11 diagnostic tests using latent class analysis (LCA). A cross-sectional survey was undertaken in a low endemicity area of the municipality of Malacacheta, Minas Gerais, Brazil. Feces, urine, and blood samples were collected from 400 residents older than 6 years of age, who had not been treated with praziquantel in the 12 months previous to the collection of their samples. The collected samples were examined using parasitological (Helm Test® kit Kato-Katz), nucleic acid amplification tests -NAATs (PCR, qPCR and LAMP on urine; PCR-ELISA, qPCR and LAMP on stool), and immunological (POC-CCA, the commercial anti-Schistosoma mansoni IgG ELISA kit from Euroimmun, and two in-house ELISA assays using either the recombinant antigen PPE or the synthetic peptide Smp150390.1) tests.
ResultsThe positivity rate of the 11 tests evaluated ranged from 5% (qPCR on urine) to 40.8% (commercial ELISA kit). The estimated prevalence of schistosomiasis was 12% (95% CI: 9–15%) according to the LCA. Among all tests assessed, the commercial ELISA kit had the highest estimated sensitivity (100%), while the Kato-Katz had the highest estimated specificity (99%). Based on the accuracy measures observed, we proposed three 2-step diagnostic approaches for the active search of infected people in endemic settings. The approaches proposed consist of combinations of commercial ELISA kit and NAATs tests performed on stool. All the approaches had higher sensitivity and specificity than the mean values observed for the 11 tests (70.4 and 89.5%, respectively).
ConclusionWe showed that it is possible to achieve high specificity and sensitivity rates with lower costs by combining serological and NAATs tests, which would assist in the decision-making process for appropriate allocation of public funding aiming to achieve the WHO target of eliminating schistosomiasis as a public health problem by 2030.

研究背景：血吸虫病是一种与贫困相关的寄生虫病。据估计，拉丁美洲有710万人感染曼氏血吸虫（Schistosoma mansoni），其中95%居住在巴西。准确诊断与及时治疗是控制和消除血吸虫病的重要手段，但目前仍需优化检测手段，尤其是在低流行地区的感染检测方面。

研究方法：本研究旨在通过潜伏类别分析（Latent Class Analysis, LCA）评估11种诊断检测方法的性能。研究在巴西米纳斯吉拉斯州马拉卡谢塔市（Malacacheta）的低流行区域开展了一项横断面调查。研究招募了400名6岁以上、且在样本采集前12个月内未接受过吡喹酮（praziquantel）治疗的居民，收集其粪便、尿液与血液样本。检测方法涵盖：寄生虫学检测（Helm Test® Kato-Katz粪便检测试剂盒）、核酸扩增检测（Nucleic Acid Amplification Tests, NAATs，包括尿液样本的聚合酶链式反应（PCR）、实时定量聚合酶链式反应（qPCR）与环介导等温扩增（LAMP）；粪便样本的聚合酶链式反应-酶联免疫吸附试验（PCR-ELISA）、qPCR与LAMP），以及免疫学检测（POC-CCA、欧蒙（Euroimmun）公司商业化抗曼氏血吸虫IgG酶联免疫吸附试验（ELISA）试剂盒，以及2种采用重组抗原PPE或合成肽Smp150390.1的室内ELISA检测方法）。

研究结果：本次评估的11种检测方法的阳性率范围为5%（尿液qPCR）至40.8%（商业化ELISA试剂盒）。通过LCA估算的血吸虫病流行率为12%（95%置信区间：9%~15%）。在所有受试检测方法中，商业化ELISA试剂盒的估算灵敏度最高（100%），而Kato-Katz法的估算特异度最高（99%）。基于观测到的准确度指标，本研究提出了3种适用于流行地区感染人群主动筛查的两步诊断方案，该方案均采用商业化ELISA试剂盒与粪便核酸扩增检测组合的形式。所有方案的灵敏度与特异度均高于11种检测方法的平均水平（分别为70.4%与89.5%）。

研究结论：本研究证实，通过联合血清学检测与核酸扩增检测，可在降低成本的同时获得较高的灵敏度与特异度，这将有助于为公共卫生资金的合理分配提供决策依据，助力实现世界卫生组织（WHO）提出的2030年消除血吸虫病作为公共卫生问题的目标。