COMPARISON OF A PARASITE LACTATE DEHYDROGENASE–BASED IMMUNOCHROMATOGRAPHIC ANTIGEN DETECTION ASSAY (OPTIMALt) WITH MICROSCOPY FOR THE DETECTION OF MALARIA PARASITES IN

Abstract. Microscopic examination of blood smears remains the gold standard for malaria diagnosis, but is labor-intensive and requires skilled operators. Rapid dipstick technology provides a potential alternative. A study was conducted in The Gambia to compare the performance of OptiMALt, an immunochromatographic antigen detection assay for the diagnosis of malaria using parasite lactate dehydrogenase, against standard microscopy in patients with suspected malaria. For initial diagnosis of Plasmodium falciparum, irrespective of stage, this assay had a sensitivity of 91.3%, a specificity of 92%, a positive predictive value of 87.2%, and a negative predictive value of 94.7%. The sensitivity of the test decreased markedly at parasitemias, 0.01%. This assay can be used for the diagnosis of malaria in areas where microscopy is not available and for urgent malaria diagnosis at night and at weekends, when routine laboratories are closed and when relatively inexperienced microscopists may be on duty. Microscopic examination of thick blood smears is the most widely used routine method for determining malaria infection in humans and remains the gold standard for ma-laria diagnosis. However, microscopic examination is labor-intensive and individuals that examine slides need to be skilled and experienced to differentiate parasites from arti