Diagnosis of malaria remains a challenge. Viable diagnostic methods need to be accurate, fast, robust and affordable. Here we present preliminary data from field trials in Papua New Guinea (PNG) and Thailand, testing a novel magneto-optical (MO) technique with the capability to meet these requirements. MO diagnosis is based on measuring hemozoin, a magnetic by-product of parasite metabolism contained in infected red cells. The method is described in detail in our previous publications.1
Patients with malaria symptoms presenting to local health centres in PNG and Thailand were asked to provide capillary blood samples (250 µL). Expert light microscopy (LM) and rapid diagnostic tests (RDTs) served as reference methods to the MO tests.
At present, 188 blood samples have been tested for malaria by all three methods, LM, RDT and MO test. Of those samples positive for Plasmodium falciparum (Pf) by LM (n=48), 94% were also positive by MO test. All samples positive by LM for Plasmodium vivax (Pv, n=12 from PNG, n=33 from Thailand), and mixed Pf/Pv infections (n=5), were also positive by MO test. This resulted in an overall sensitivity of 95% of the MO test vs. LM. Parasite density, as determined by LM, correlated strongly with MO signals (R2=0.49, Pf; R2=0.86, Pv, P<0.001), resulting in an estimated threshold of detection of the MO method of 88/µL for Pf, and 5/µL for Pv. Results from molecular diagnosis are pending. These preliminary data indicate that the novel MO method can reliably detect malaria infection in symptomatic patients, and exhibits a lower estimated detection threshold for Pv, compared to LM and current RDTs. Furthermore, the method is rapid and cost-effective.
Our MO method has considerable potential to be developed into a viable tool for malaria diagnosis.