Department of Laboratory Medicine, Ghent University Hospital (GUH), De Pintelaan 185, 9000, Ghent, Belgium.
Institute of Tropical Medicine (ITM) Antwerp, Nationalestraat 155, 2000, Antwerp, Belgium.
Malar J. 2017 Oct 17;16(1):418. doi: 10.1186/s12936-017-2065-8.
BACKGROUND: Light microscopy and antigen-based rapid diagnostic tests are the primary diagnostic tools for detecting malaria, although being labour-intensive and frequently challenged by lack of personnel's experience and low levels of parasite density. The latter being especially important in non-endemic settings. Novel molecular techniques aim to overcome this drawback. The objective of this study was to assess the diagnostic performance of the illumigene malaria assay (Meridian Bioscience) compared to microscopy, RDT and real-time PCR. This loop-mediated isothermal amplification (LAMP) assay is a qualitative in vitro diagnostic test for the direct detection of Plasmodium spp. DNA in human venous whole blood samples. METHODS: The illumigene assay was assessed on a retrospective panel of stored blood samples (n = 103) from returned travellers and external quality control samples (n = 12). Additionally the assay was prospectively assessed on 30 fresh routine samples with a request for malaria diagnosis. The illumigene assay was compared to microscopy, RDT and Plasmodium species specific real-time PCR. RESULTS: In the retrospective evaluation, the illumigene assay showed 100% agreement with the real-time PCR, RDT and microscopy yielding a sensitivity and specificity of 100% (95% CI 95.1-100% and 89.7-100%, respectively). Seven samples from patients recently treated for Plasmodium falciparum infection that were RDT positive and microscopy negative yielded positive test results. The performance of the illumigene assay equals that of microscopy combined with RDT in the prospective panel with three false negative RDT results and one false negative microscopy result. Excellent concordance with PCR was observed. The limit of detection of the assay approached 0.5 parasites/µL for both P. falciparum and Plasmodium vivax. CONCLUSION: In non-endemic regions where the diagnostic process for malaria infections is questioned by lack of experience and low levels of parasite densities, the illumigene assay can be of value. Due to its high sensitivity, the LAMP assay may be considered as primary diagnostic test. The results of this study indicate that negative screen results do not need further confirmation. However, before implementation, this approach needs to be confirmed in larger, prospective studies. A shortcoming of this assay is that no species identification nor determination of parasite density are possible.
背景:尽管显微镜检查和抗原快速诊断检测是检测疟疾的主要诊断工具,但这些方法既耗费人力,又常常受到人员经验不足和寄生虫密度低的影响。在非流行地区,后者尤为重要。新型分子技术旨在克服这一缺陷。本研究旨在评估 illumigene 疟疾检测(Meridian Bioscience)与显微镜检查、RDT 和实时 PCR 的诊断性能。该环介导等温扩增(LAMP)检测法是一种定性的体外诊断检测法,用于直接检测人类静脉全血样本中的疟原虫 spp. DNA。
方法:对来自返回旅行者的储存血液样本回顾性检测(n=103)和外部质量控制样本(n=12)评估 illumigene 检测。此外,对 30 份有疟疾诊断请求的新鲜常规样本进行前瞻性评估。将 illumigene 检测与显微镜检查、RDT 和疟原虫种特异性实时 PCR 进行比较。
结果:在回顾性评估中,illumigene 检测与实时 PCR、RDT 和显微镜检查完全一致,灵敏度和特异性均为 100%(95%CI 95.1-100%和 89.7-100%)。7 份来自近期接受恶性疟原虫感染治疗的患者的样本,RDT 阳性而显微镜检查阴性,检测结果为阳性。在前瞻性样本中,illumigene 检测的性能与显微镜检查和 RDT 相当,有 3 份 RDT 假阴性和 1 份显微镜假阴性结果。与 PCR 观察到极好的一致性。该检测法的检测限接近 0.5 个寄生虫/µL,适用于恶性疟原虫和间日疟原虫。
结论:在寄生虫密度低和缺乏经验导致疟疾感染诊断受到质疑的非流行地区,illumigene 检测可能具有价值。由于其高灵敏度,LAMP 检测法可作为初步诊断检测法。本研究结果表明,阴性筛查结果无需进一步确认。然而,在实施之前,这种方法需要在更大的前瞻性研究中得到确认。该检测法的一个缺点是无法进行物种鉴定或寄生虫密度测定。
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