A simple and fast method to exclude high Plasmodium falciparum parasitaemia in travellers with imported malaria

Counts of malaria parasites in peripheral blood are important to assess severity of Plasmodium falciparum malaria. Thin and thick smears are routinely used for this purpose. In this study the Binax NOW Malaria Test, an easy-to-perform rapid diagnostic test, with Histidine Rich Protein-2 (HRP-2) and aldolase as diagnostic markers, was used for semi-quantitative assessment of parasitaemia of P. falciparum. In 257 patients with imported P. falciparum malaria, reactivity of aldolase increased with higher parasitaemia. In all patients with a parasitaemia above 50,000 asexual parasites/μl (> 1%) co-reactivity of HRP-2 and aldolase was observed. Absence of aldolase reactivity in the presence of HRP-2 was a reliable predictive marker to exclude high (> 1%) parasitaemia in P. falciparum malaria. Assessment of HRP-2 and aldolase co-reactivity can be of help in clinical decision making in the acute care setting of returning travellers suspected of having malaria