Abstract
BackgroundThe 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.MethodsPanels 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.ResultsAnalysis 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.ConclusionsGlobally, 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.
Highlights
The World Health Organization (WHO) recommends parasite-based diagnosis of malaria
Microscopy and rapid diagnostic tests (RDTs) are the main tools used for malaria case management and routine surveillance in endemic countries [2]
55 survey respondents who reported that they perform Nucleic acid amplification technique (NAAT) for Plasmodium detection were invited to participate in the external quality assessment (EQA) scheme, consisting of two distributions per year, on condition of signing a letter of agreement with WHO
Summary
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. 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. Over the last 30 years, important advances in molecular techniques have led nucleic acid amplification-based tests (NAATs) to be increasingly used for identification of Plasmodium infection. Since the advent of conventional PCR, numerous additional modifications have been developed, including nested PCR, real-time PCR, multiplex PCR, reverse transcription PCR, and loop-mediated isothermal amplifications (LAMP) [5,6,7,8,9,10,11,12]
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