P. falciparum Parasitemia & Band Sensitivity of SD Bioline Malaria Ag P.f/Pan RDT in Madagascar

Current malaria rapid diagnostic tests (RDTs) contain antibodies against -specific histidine-rich protein 2 (PfHRP2), lactate dehydrogenase (pLDH), and aldolase in various combinations. Low or high parasite densities/target antigen concentrations may influence the accuracy and sensitivity of PfHRP2-detecting RDTs. We analyzed the SD Bioline Malaria Ag P.f/Pan RDT performance in relation to parasitemia in Madagascar, where clinical malaria exists alongside . Nine hundred sixty-three samples from patients seeking care for suspected malaria infection were analyzed by RDT, microscopy, and species-specific, ligase detection reaction-fluorescent microsphere assay (LDR-FMA). infection positivity by these diagnostics was 47.9%, 46.9%, and 58%, respectively. -only infections were predominant (microscopy, 45.7%; LDR-FMA, 52.3%). In all, 16.3% of , 70% of , and all of , , and mixed-species infections were submicroscopic. In 423 mono-infections, confirmed by microscopy and LDR-FMA, the parasitemia in those who were positive for both the PfHRP2 and pan-pLDH test bands was significantly higher than that in those who were positive only for the PfHRP2 band ( < 0.0001). parasitemia in those that were detected as -only infections by microscopy but mixed infections by LDR-FMA also showed similar outcome by the RDT band positivity. In addition, we used varying parasitemia (3-0.0001%) of the laboratory-maintained 3D7 strain to validate this observation. A positive pLDH band in high -parasitemic individuals may complicate diagnosis and treatment, particularly when the microscopy is inconclusive for , and the two infections require different treatments.