Malaria rapid diagnostic devices: Performance characteristics of the ParaSight F device determined in a multisite field study

Microscopic detection of parasites has been the reference standard for mala ria diagnosis for decades. However, difficulty in maintaining required tech nical skills and infrastructure has spurred the development of several nonm icroscopic malaria rapid diagnostic devices based on the detection of malar ia parasite antigen in whole blood. The ParaSight F test is one such device . It detects the presence of Plasmodium falciparum-specific histidine-rich protein 2 by using an antigen-capture immunochromatographic strip format. T he present study was conducted at outpatient malaria clinics in Iquitos, Pe ru, and Maesod, Thailand. Duplicate, blinded, expert microscopy was employe d as the reference standard for evaluating device performance. Of 2,988 eli gible patients, microscopy showed that 547 (18%) had P. falciparum, 658 (22 %) had P. vivax, 2 (0.07%) had P. malariae, and 1,750 (59%) were negative f or Plasmodium. Mixed infections (P. falciparum and P. vivax) were identifie d in 31 patients (1%). The overall sensitivity of ParaSight F for P. falcip arum was 95%. When stratified by magnitude of parasitemia (no. of asexual p arasites per microliter of whole blood), sensitivities were 83% (>0 to 500 parasites/mul), 87% (501 to 1,000/mul), 98% (1,001 to 5,000/mul), and 98% ( >5,000/mul). Device specificity was 86%.