Sensitive Detection of Asymptomatic and Symptomatic Malaria with Seven Novel Parasite-Specific LAMP Assays and Translation for Use at Point-of-Care
Date
2023
Journal Title
Journal ISSN
Volume Title
Publisher
Microbiology Spectrum
Abstract
Human malaria is a life-threatening parasitic disease with high impact in the
sub-Saharan Africa region, where 95% of global cases occurred in 2021. While most malaria
diagnostic tools are focused on Plasmodium falciparum, there is a current lack of testing
non-P. falciparum cases, which may be underreported and, if undiagnosed or untreated,
may lead to severe consequences. In this work, seven species-specific loop-mediated
isothermal amplification (LAMP) assays were designed and evaluated against TaqMan quan titative PCR (qPCR), microscopy, and enzyme-linked immunosorbent assays (ELISAs).
Their clinical performance was assessed with a cohort of 164 samples of symptomatic
and asymptomatic patients from Ghana. All asymptomatic samples with a parasite load
above 80 genomic DNA (gDNA) copies per mL of extracted sample were detected
with the Plasmodium falciparum LAMP assay, reporting 95.6% (95% confidence interval
[95% CI] of 89.9 to 98.5) sensitivity and 100% (95% CI of 87.2 to 100) specificity. This
assay showed higher sensitivity than microscopy and ELISA, which were 52.7% (95% CI
of 39.7 to 67%) and 67.3% (95% CI of 53.3 to 79.3%), respectively. Nine samples were posi tive for P. malariae, indicating coinfections with P. falciparum, which represented 5.5% of
the tested population. No samples were detected as positive for P. vivax, P. ovale, P. knowl esi, or P. cynomolgi by any method. Furthermore, translation to the point-of-care was
demonstrated with a subcohort of 18 samples tested locally in Ghana using our hand held lab-on-chip platform, Lacewing, showing comparable results to a conventional fluo rescence-based instrument. The developed molecular diagnostic test could detect asymp tomatic malaria cases, including submicroscopic parasitemia, and it has the potential to
be used for point-of-care applications
Description
Research Article
Keywords
nucleic acid amplification,, malaria, diagnostics, point-of-care