Diagnosis of malaria by detection of Plasmodium falciparum HRP-2 antigen with a rapid dipstick antigen-capture assay

Two field studies in Kenya and an experimental challenge study in the USA were done to assess the accuracy of a dipstick antigen-capture assay based on qualitative detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP-2) in peripheral blood for diagnosis of P falciparum infection. In these studies, the assay was 96·5-100% sensitive for detection of greater than 60 P falciparum asexual parasites/ μL blood, 70-81% sensitive for 11-60 parasites/μL blood, and 11-67% sensitive for 10 parasites or less/μL blood. Specificity was 95% (95% Cl 85-105%; n = 20) among naive American volunteers, 98% (96-101%; n=112) among volunteers exposed to the bite of P falciparium-infected mosquitoes, and 88% (84-92%; n=285) among Kenyans living in an area with holoendemic malaria. Our results also indicated that PfHRP-2 antigen was not detectable in blood 6 days after initiation of curative chemotherapy, and suggest that such circulating antigens rarely lead to false-positive tests. The dipstick assay's sensitivity, specificity, simplicity, and speed may make it an important tool in the battle against malaria. © 1994.