Abstract
BackgroundLight 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.MethodsThe 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.ResultsIn 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.ConclusionIn 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.
Highlights
Light microscopy and antigen-based rapid diagnostic tests are the primary diagnostic tools for detect‐ ing malaria, being labour-intensive and frequently challenged by lack of personnel’s experience and low lev‐ els of parasite density
Most rapid diagnostic tests (RDTs) currently used are based on immunochromatographic techniques which detect histidine-rich protein 2 (HRP-2), a protein specific to Plasmodium falciparum, and panPlasmodium parasite lactate dehydrogenase or aldolase, enzymes common to all Plasmodium species [7]
The main objective of our study was to assess the diagnostic performance of the illumigene Malaria DNA Amplification assay® (Meridian Bioscience, Inc., Cincinnati OH, USA), compared to microscopy, RDT and realtime Polymerase chain reaction (PCR) for Plasmodium spp. detection
Summary
Light microscopy and antigen-based rapid diagnostic tests are the primary diagnostic tools for detect‐ ing malaria, being labour-intensive and frequently challenged by lack of personnel’s experience and low lev‐ els of parasite density. The latter being especially important in non-endemic settings. Microscopic examination of Giemsa-stained blood slides (thin and thick films) by trained and experienced staff has been the standard for malaria diagnosis for nearly a century [1, 12] This technique is labour-intensive, time consuming and challenged by a high limit of detection (LoD). The sensitivity for non-falciparum species varies between different RDTs used (Plasmodium vivax: 66.0–88.0%; Plasmodium ovale: 5.5–86.7%; P. malariae: 21.4–45.2%), with a marked decline in sensitivity at parasite densities below 500/μL [6, 14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
