Efficient monitoring of blood-stage infection in a malaria rodent model by the rotating-crystal magneto-optical method

TL;DR

This study demonstrates that the magneto-optical method can rapidly and sensitively detect blood-stage malaria infections in a mouse model, outperforming traditional microscopy and flow cytometry, with potential for field diagnosis.

Contribution

The paper introduces the application of the magneto-optical method for in vivo monitoring of malaria infection progression in a rodent model, showing improved sensitivity and feasibility for clinical use.

Findings

Detects first intraerythrocytic parasites at 61-66 hours post-infection

Outperforms light microscopy and flow cytometry in sensitivity

Can monitor hemozoin clearance over 5 days after treatment

Abstract

Global research efforts have been focused on the simultaneous improvement of the efficiency and sensitivity of malaria diagnosis in resource-limited settings and for the active case detection of asymptomatic infections. A recently developed magneto-optical (MO) method allows the high-sensitivity detection of malaria pigment (hemozoin) crystals in blood via their magnetically induced rotational motion. The evaluation of the method using synthetic $\beta$-hematin crystals and P. falciparum in vitro cultures implies its potential for in-field diagnosis. Here, we study the performance of the method in monitoring the in vivo onset and progression of the blood stage infection using a malaria mouse model. We found that the MO method can detect the first generation of intraerythrocytic parasites at the ring stage 61-66 hours after sporozoite injection demonstrating better sensitivity than light microscopy and flow cytometry. MO measurements performed after treatment of severe P. berghei infections show that the clearance period of hemozoin in mice is approx. 5 days which indicates the feasibility of the detection of later reinfections as well. Being label and reagent-free, cost-effective and rapid, together with the demonstrated sensitivity, we believe that the MO method is a suitable candidate for in-depth clinical evaluation in endemic settings.