Diagnostic performance of a 5-plex malaria immunoassay
Scientific Reports | May 4th, 2022
Steven Kho, Nicholas M. Anstey, Bridget E. Barber, Kim Piera, Timothy William, Enny Kenangalem, James S. McCarthy, Ihn Kyung Jang, Gonzalo J. Domingo, Sumudu Britton, and Matthew J. Grigg
Quansys Products Used:
Commercial point-of-care tests remain insufficient for accurately detecting and differentiating low-level malaria infections in regions co-endemic with multiple non-falciparum species, including zoonotic Plasmodium knowlesi (Pk). A 5-plex chemiluminescent assay simultaneously measures pan-Plasmodium lactate dehydrogenase (pLDH), P. falciparum (Pf)-LDH, P. vivax (Pv)-LDH, Pf-histidine-rich protein-2 (HRP2), and C-reactive protein. We assessed its diagnostic performance on whole blood (WB) samples from 102 healthy controls and 306 PCR-confirmed clinical cases of Pf, Pv, Pk, P. malariae (Pm) and P. ovale (Po) mono-infections from Southeast-Asia. We confirm its excellent HRP2-based detection of Pf. Cross-reactivity of Pf-LDH with all non-falciparum species tested was observed (specificity 57.3%). Pv-LDH performance was suboptimal for Pv (93.9% sensitivity and 73.9% specificity). Poor specificity was driven by strong Pk cross-reactivity, with Pv-LDH detecting 93.9% of Pk infections. The pan-LDH-to-Pf-LDH ratio was capable of discerning Pv from Pk, and robustly differentiated Pf from Pm or Po infection, useful in regions with hrp2/3 deletions. We tested the platform’s performance in plasma for the first time, with WB outperforming plasma for all analytes except Pv-LDH for Pk. The platform is a promising tool for WB malaria diagnosis, although further development is warranted to improve its utility in regions co-endemic for multiple non-falciparum species.