Rapid diagnosis of severe malaria based on the detection of Pf-Hrp-2 antigen

Blood samples collected from 34 patients with severe malaria who were invol ved in antimalarial treatment studies were tested with rapid dipstick assay (Rapid Test Malaria (TM), RTM from Quorum Diagnostics Inc., Vancouver, BC, Canada), based on the detection of Histidine Rich Protein (HRP-2) of Plasm odium falciparum. This was compared with the conventional Giemsa stained th in and thick blood smears. The study was done from March 1998 to May 1998, at the Basic Research Laboratory of the Faculty of Medicine, Addis Ababa Un iversity. Comparable number of patients (n=32) with various diagnosis other than falciparum malaria were used as controls. The rapid dip-stick assay w as positive in 31 among 34 of the severe malaria cases with sensitivity of 91.2%, specificity of 93.7%, positive predictive value (PPV) of 93.9% and n egative predictive value (NPV) of 90.9%. The three cases missed by the RTM, had parasitemia of 66000, 44000, and 40000/mu L of blood which might be du e to genetic heterogeneity of the HPR-2 expression. Among the controls, the re were 2 false positive cases which may be a result of persistent HPR-2 an tigen after the clearance of peripheral parasitemia. The dip-stick method i s a very quick, sensitive and specific diagnostic tool with limits of detec tion comparable or better than those provided by the light microscopy. The simplicity of the technique makes this method more applicable in the resour ce deprived laboratories of developing countries provided the kit is afford able for large scale use.