Rapid Diagnosis of Falciparum Malaria

In recent years, several rapid diagnostic tests for falciparum malaria have been developed. KATTM test results were compared with microscopy on 90 consecutive patients hospitalized at the Hospital for Tropical Diseases, Bangkok, Thailand. Fifty-one patients had P. falciparum infections while 49 had malaria due to other plasmodium species. For a geometric mean ±SD (Min;Max;range) parasitemia of 11,481 ± 5.0 (88;713,838;713,750), the sensitivity of the KAT test was 96% (95% CI=86-99.5), the specificity was 92% (95% CI=80-99), the accuracy was 94% and the reliability was 85%. These findings suggest that the KATTM test is of potential interest in the diagnosis of falciparum malaria in Thailand. SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 36 Vol 35 No. 1 March 2004 December 2000 at the Hospital for Tropical Diseases in Bangkok, Thailand. The study was approved by the Ethics Committee of the Faculty of Tropical Medicine, Mahidol University. Ninety consecutive patients with microscopically diagnosed malaria (P. falciparum, P. vivax, P. malariae or P. ovale) were recruited after informed consent. The fingerprick blood samples were used to prepare thick and thin blood films, which were stained with 10% Giemsa solution and examined microscopically at 1,000 x magnification. The microscopists at the Hospital for Tropical Diseases are highly experienced in the diagnosis of malaria and quality control is regular. The number of malaria parasites per microliter of blood was determined by counting the number of parasites per 1,000 red blood cells in thin films and per 200 white blood cells on thick films. In cases where thick blood films were missing or uncountable (too many parasites), the number of malaria parasites was calculated using a thin blood film and red blood cells. Blood films were considered negative if no parasites were seen in 200 oil-immersion fields on a thick blood film. Another 10 μl of blood was collected into a microcapillary tube and immediately tested using the KATTM-Quick Malaria Rapid Test following the manufacturer’s instructions. The test consists of a strip encased in a plastic housing in which blood and buffer are added. The principle of this test is to immobilize a capture monoclonal antibody on the nitrocellulose strip. The red blood cells are lysed releasing PfHRP-II which binds selectivity to this antibody as the blood is wicked up the strip. The signal reagent is coated with specific antibodies which bind with the antibody-antigen complex, producing a red line (the procedural control line) demonstrates the test has been performed correctly.