Magneto-optical diagnosis of symptomatic malaria in Papua New Guinea

L Arndt,L Timinao,P Kaman,Á Butykai,A P Molnár,M Laman,S Krohns,C Ibam,L J Robinson,B Moore,E Nate,Á Orbán,I Kézsmárki,L Lorry,E Orosz,E Lufele,I Kucsera,T Koleala,S Karl

doi:10.1038/s41467-021-21110-w

Abstract

Improved methods for malaria diagnosis are urgently needed. Here, we evaluate a novel method named rotating-crystal magneto-optical detection (RMOD) in 956 suspected malaria patients in Papua New Guinea. RMOD tests can be conducted within minutes and at low cost. We systematically evaluate the capability of RMOD to detect infections by directly comparing it with expert light microscopy, rapid diagnostic tests and polymerase chain reaction on capillary blood samples. We show that compared to light microscopy, RMOD exhibits 82% sensitivity and 84% specificity to detect any malaria infection and 87% sensitivity and 88% specificity to detect Plasmodium vivax. This indicates that RMOD could be useful in P. vivax dominated elimination settings. Parasite density correlates well with the quantitative magneto-optical signal. Importantly, residual hemozoin present in malaria-negative patients is also detectable by RMOD, indicating its ability to detect previous infections. This could be exploited to reveal transmission hotspots in low-transmission settings.

Highlights

Improved methods for malaria diagnosis are urgently needed
Measurements on parasite cultures indicated that rotating-crystal magneto-optical detection (RMOD) had a limit of detection (LOD) of ∼10 parasites per μL of blood in samples spiked with P. falciparum[26]
Overall, based on light microscopy (LM) diagnosis 34% of patients were positive for any malaria infection, as compared to 37% and 34% by rapid diagnostic tests (RDTs) and polymerase chain reaction (PCR) methods, respectively

Summary

Introduction

Improved methods for malaria diagnosis are urgently needed. Here, we evaluate a novel method named rotating-crystal magneto-optical detection (RMOD) in 956 suspected malaria patients in Papua New Guinea. Residual hemozoin present in malaria-negative patients is detectable by RMOD, indicating its ability to detect previous infections This could be exploited to reveal transmission hotspots in low-transmission settings. A promising concept for hemozoin-based malaria diagnosis was described by Newman and colleagues in 200818 This applicability of the method was demonstrated using synthetic hemozoin (β-hematin) samples, but the ability to detect infections in a set of LM-confirmed patient samples under laboratory conditions, was considered requiring further development[16]. Building upon this concept, over recent years, we developed a novel diagnostic technique, named rotating-crystal magneto-optical detection (RMOD). While many aspects of hemozoin clearance and redistribution in the human body are yet to be elucidated, there is evidence for long-term persistence of hemozoin in body tissues of people living in endemic areas[31,37]

Methods

Results

Conclusion