Malaria and Neglected Tropical Diseases Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, Biomedical Research Networking Center of Infectious Diseases, Madrid, Spain.
Cooperative Research Network in Tropical Diseases, Madrid, Spain.
Trop Med Int Health. 2022 Aug;27(8):686-695. doi: 10.1111/tmi.13786. Epub 2022 Jun 21.
Loa loa and Mansonella perstans are two very common filarial species in Africa. Although microscopy is the traditional diagnostic method for human filariasis, several polymerase chain reaction (PCR) methods have emerged as an alternative approach for identifying filarial parasites. The aim of this study is to compare three molecular methods and decide which is the most suitable for diagnosing human loiasis and mansonellosis in non-endemic regions using dried blood spot (DBS) as a medium for sample collection and storage.
A total of 100 DBS samples, with their corresponding thin and thick blood smears, were selected for this study. Microscopy was used as the reference method to diagnose and calculate the microfilaraemia. Filarial DNA was extracted using the saponin/Chelex method and the DNA isolated was assayed by Filaria-real time-PCR, filaria-nested PCR, and cytochrome oxidase I PCR. All PCR products were subsequently purified and sequenced. The statistical values for each molecular test were calculated and compared.
Overall, 64 samples were identified as negative by all tests and a further 36 samples were positive by at least one of the methods used. The sensitivity and specificity were similar for the different molecular methods, all of which demonstrated good agreement with microscopy.
Based on this study, and from a practical point of view (single and short amplification round), the optimal technique for diagnosing filarial infection in non-endemic regions is filaria-real time-PCR, which presents high sensitivity and specificity and is also able to detect a wide range of human filariae.
Loa loa 和 Mansonella perstans 是两种在非洲非常常见的丝虫。尽管显微镜检查是诊断人体丝虫病的传统方法，但已经出现了几种聚合酶链反应（PCR）方法作为替代方法来识别丝虫寄生虫。本研究的目的是比较三种分子方法，并确定哪种方法最适合使用干血斑（DBS）作为样本收集和储存的介质，在非流行地区诊断人类罗阿丝虫病和曼森线虫病。
本研究共选择了 100 份 DBS 样本及其相应的薄血涂片和厚血涂片。显微镜检查被用作参考方法来诊断和计算微丝蚴血症。使用皂素/Chelex 法提取丝虫 DNA，并用 Filaria-real time-PCR、丝虫巢式 PCR 和细胞色素氧化酶 I PCR 检测 DNA。随后对所有 PCR 产物进行纯化和测序。计算并比较了每种分子检测的统计值。
总体而言，所有测试均将 64 个样本鉴定为阴性，而至少有一个方法鉴定为阳性的样本进一步增加到 36 个。不同分子方法的敏感性和特异性相似，所有方法均与显微镜检查具有良好的一致性。
根据本研究，从实际角度（单轮和短扩增轮）来看，诊断非流行地区丝虫感染的最佳技术是丝虫实时 PCR，该技术具有高敏感性和特异性，并且能够检测广泛的人体丝虫。
