Estimation of parasite load using Rapid diagnostic test ICT ®Now Malaria P.f/P.v in Plasmodium falciparum malaria

Abstract

Rapid tests such as ICT Malaria are an effective field tool in determining the presence of malarial parasites but do not provide an estimate of parasite load. We have evaluated the utility of ICT for providing semi-quantitative estimates of parasite load. Circulating parasite load in the blood of patients with malaria (n =54), were compared with the circulating HRP2 protein levels. Blood was serially diluted and analysed by a rapid diagnostic test (ICT® Now P.f/P.v) for assessment of endpoint PfHRP2 antigen titres. Significant correlation was observed between parasite load and PfHRP2 antigen titres (Spearman rank; rho = 0.821; p<0.001) with plasma dilutions > 1:16 corresponding to a parasite load of 0.1% parasitaemia. Variability in haematological parameters had no effect on the antibody titres obtained with the ICT test. Rapid semi-quantitative assessment of parasite load in conjunction with the Plasmodium speciation may provide a useful bedside and field aid in the diagnosis of malaria.