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 ass ay based on qualitative detection of Plasmodium falciparum histidine-r ich protein 2 (PfHRP-2) in peripheral blood for diagnosis of P fafcipa rum infection. In these studies, the assay was 96.5-100% sensitive for detection of greater than 60 P falciparum asexual parasites/ mu L blo od, 70-81% sensitive for 11-60 parasites/mu L blood, and 11-67% sensit ive for 10 parasites or less/mu L blood. Specificity was 95% (95% CI 8 5-105%; n = 20) among naive American volunteers, 98% (96-101%; n=112) among volunteers exposed to the bite of P falciparium-infected mosquit oes, and 88% (84-92%; n=285) among Kenyans living in an area with holo endemic malaria. Our results also indicated that PfHRP-2 antigen was n ot detectable in blood 6 days after initiation of curative chemotherap y, and suggest that such circulating antigens rarely lead to false-pos itive tests. The dipstick assay's sensitivity, specificity, simplicity , and speed may make it an important tool in the battle against malari a.