A comparative study of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) blood levels and peripheral blood parasitemia as parameters of disease severity in individuals with imported falciparum malaria.

BACKGROUND:In falciparum malaria the total parasite biomass can be estimated by blood levels of histidine-rich protein 2 (PfHRP2), a Plasmodium falciparum-specific protein, which has been widely studied in malaria-endemic regions. This study investigates the usefulness of PfHRP2 as marker for disease severity in imported falciparum malaria. METHODS:A retrospective cohort analysis was done in 145 patients with imported falciparum malaria. Associations between PfHRP2, malaria disease severity and classic parameters of disease severity were examined by statistical analyses. Patients with different travel purposes were examined in two groups: visiting friends and relatives (VFRs) and other travel purposes (mainly tourists). RESULTS:High PfHRP2 levels were clearly associated with disease severity. VFRs status showed to be an independent determinant protecting against severe malaria. At similar PfHRP2 levels VFRs patients had significantly lower levels of peripheral blood parasitemia compared to other patients. CONCLUSION:Our study confirms the association between PfHRP2 and disease severity in patients with imported falciparum malaria, but for proper interpretation of PfHRP2 levels as disease severity marker in travellers, the possible presence of pre-existing acquired anti-malarial immunity should be taken into account as the correlation between PfHRP2 levels and disease severity differed significantly between VFRs patients and patients with other travel purposes.