Sensitive detection of Plasmodium vivax malaria by the rotating-crystal magneto-optical method in Thailand

Abstract

The rotating-crystal magneto-optical detection (RMOD) method has been developed for the rapid and quantitative diagnosis of malaria and tested systematically on various malaria infection models. Very recently, an extended field trial in a high-transmission region of Papua New Guinea demonstrated its great potential for detecting malaria infections, in particular Plasmodium vivax. In the present small-scale field test, carried out in a low-transmission area of Thailand, RMOD confirmed malaria in all samples found to be infected with Plasmodium vivax by microscopy, our reference method. Moreover, the magneto-optical signal for this sample set was typically 1–3 orders of magnitude higher than the cut-off value of RMOD determined on uninfected samples. Based on the serial dilution of the original patient samples, we expect that the method can detect Plasmodium vivax malaria in blood samples with parasite densities as low as $$\sim$$ ∼ 5–10 parasites per microliter, a limit around the pyrogenic threshold of the infection. In addition, by investigating the correlation between the magnitude of the magneto-optical signal, the parasite density and the erythrocytic stage distribution, we estimate the relative hemozoin production rates of the ring and the trophozoite stages of in vivo Plasmodium vivax infections.

Field Evaluation of a Hemozoin-Based Malaria Diagnostic Device in Puerto Lempira, Honduras

“…Furthermore, RDTs do not indicate parasite burden and may face detection problems when the parasite does not express the target antigen [13,14]. Due to the intrinsic limitations of conventional malaria diagnostic methods and the challenges faced by countries approaching elimination, a large number of new diagnostic methods have been proposed [15][16][17][18][19][20][21][22]. The most sensitive methods (around five parasites/µL of blood) are those based on DNA amplification.…”

Magneto-optical assessment of Plasmodium parasite growth via hemozoin crystal size

“…As it has been described previously, the anisotropic magnetic and optical properties of HZ can be utilized for its simple, yet highly sensitive detection and quantification in samples derived from cell cultures, animal models and malaria patients 5 , 19 , 20 . The quantification of HZ in blood samples of suspected malaria patients has the benefit of providing a quantitative parameter that can aid the assessment of disease severity, in contrast to RDTs for example, which only give a qualitative diagnostic result.…”

Magneto-optical assessment of Plasmodium parasite growth via hemozoin crystal size

“…As it has been described previously, the anisotropic magnetic and optical properties of HZ can be utilized for its simple, yet highly sensitive detection and quanti cation in samples derived from cell cultures, animal models and malaria patients 5,19,20 . Furthermore, we have demonstrated that the rotating-crystal magneto-optical detection (RMOD) developed by our research group, is an e cient tool for the assessment of drug susceptibility of P. falciparum cell cultures via the quanti cation of their HZ production with high temporal resolution 21,22 .…”