World Health Organization, Geneva, Switzerland.
Independent Consultant, London, UK.
Malar J. 2020 Mar 30;19(1):129. doi: 10.1186/s12936-020-03200-0.
The World Health Organization (WHO) recommends parasite-based diagnosis of malaria. In recent years, there has been surge in the use of various kinds of nucleic-acid amplification based tests (NAATs) for detection and identification of Plasmodium spp. to support clinical care in high-resource settings and clinical and epidemiological research worldwide. However, these tests are not without challenges, including lack (or limited use) of standards and lack of reproducibility, due in part to variation in protocols amongst laboratories. Therefore, there is a need for rigorous quality control, including a robust external quality assessment (EQA) scheme targeted towards malaria NAATs. To this effect, the WHO Global Malaria Programme worked with the UK National External Quality Assessment Scheme (UK NEQAS) Parasitology and with technical experts to launch a global NAAT EQA scheme in January 2017.
Panels of NAAT EQA specimens containing five major species of human-infecting Plasmodium at various parasite concentrations and negative samples were created in lyophilized blood (LB) and dried blood spot (DBS) formats. Two distributions per year were sent, containing five LB and five DBS specimens. Samples were tested and validated by six expert referee laboratories prior to distribution. Between 37 and 45 laboratories participated in each distribution and submitted results using the online submission portal of UK NEQAS. Participants were scored based on their laboratory's stated capacity to identify Plasmodium species, and individual laboratory reports were sent which included performance comparison with anonymized peers.
Analysis of the first three distributions revealed that the factors that most significantly affected performance were sample format (DBS vs LB), species and parasite density, while laboratory location and the reported methodology used (type of nucleic acid extraction, amplification, or DNA vs RNA target) did not significantly affect performance. Referee laboratories performed better than non-referee laboratories.
Globally, malaria NAAT assays now inform a range of clinical, epidemiological and research investigations. EQA schemes offer a way for laboratories to assess and improve their performance, which is critical to safeguarding the reliability of data and diagnoses especially in situations where various NAAT methodologies and protocols are in use.
世界卫生组织（WHO）建议采用寄生虫检测方法进行疟疾诊断。近年来，各种核酸扩增检测（NAAT）技术已广泛应用于检测和鉴定疟原虫属，以支持高资源环境下的临床护理以及全球临床和流行病学研究。然而，这些检测方法并非没有挑战，包括缺乏（或有限使用）标准和重现性差，部分原因是实验室之间的方案存在差异。因此，需要进行严格的质量控制，包括针对疟疾 NAAT 的强大外部质量评估（EQA）计划。为此，世界卫生组织全球疟疾规划与英国国家外部质量评估计划（UK NEQAS）寄生虫学合作，并与技术专家合作，于 2017 年 1 月推出了全球 NAAT EQA 计划。
在冻干血液（LB）和干血斑（DBS）格式中创建了包含五种主要人类感染疟原虫和阴性样本的 NAAT EQA 标本面板，寄生虫浓度各不相同。每年进行两次分发，包含五个 LB 和五个 DBS 标本。在分发之前，由六个专家参考实验室对标本进行测试和验证。每次分发时，有 37 至 45 个实验室参加，并使用 UK NEQAS 的在线提交门户提交结果。根据实验室声明的识别疟原虫种类的能力对参与者进行评分，并向参与者发送包括与匿名同行进行绩效比较的个别实验室报告。
对前三次分发的分析表明，对性能影响最大的因素是样本格式（DBS 与 LB）、物种和寄生虫密度，而实验室位置和报告的使用方法（核酸提取、扩增或 DNA 与 RNA 靶标类型）并没有显著影响性能。参考实验室的表现优于非参考实验室。
全球范围内，疟疾 NAAT 检测现在为一系列临床、流行病学和研究调查提供信息。EQA 计划为实验室评估和提高性能提供了一种方法，这对于确保数据和诊断的可靠性至关重要，特别是在各种 NAAT 方法和方案正在使用的情况下。
