Plasmodium falciparum histidine rich protein 2 plasma concentrations from uncomplicated and severe malaria patients estimated by rapid test band intensity

Unlike peripheral blood parasitaemia, plasma concentrations of PfHRP2 has been established as a measure of total body parasite burden in patients with falciparum malaria, which is prognostic for progression to severe malaria and case fatality. Plasma PfHRP2 concentrations are typically quantified using enzyme-linked immunosorbent assay (ELISA) methods. We assessed whether band intensity on a PfHRP2-based ultrasensitive rapid diagnostic test (RDT) can provide a semi-quantitative measure for plasma PfHRP2 concentrations. Plasma samples from 60 African patients with severe falciparum malaria and 20 patients with uncomplicated falciparum malaria were assessed for PfHRP2 by ELISA and compared with RDT band intensity, assessed both visually and by digital scanning. Visual readings of RDT band intensity correlated with PfHRP2 plasma concentrations assessed by ELISA in patients with both uncomplicated (ρ = 0.80) and severe falciparum malaria (ρ = 0.61). Digitally assessed RDT band intensity in patients with severe malaria was higher than in patients with uncomplicated falciparum malaria. RDT band intensity correlates with plasma PfHRP2 concentration measured by ELISA and may offer a simple method for estimating total parasite burden in patients with falciparum malaria.