Field evaluation of the ICT malaria P.f/P.v immunochromatographic test fordetection of Plasmodium falciparum and Plasmodium vivax in patients with apresumptive clinical diagnosis of malaria in eastern Indonesia

In areas such as eastern Indonesia where both Plasmodium falciparum and Pla smodium vivax occur, rapid antigen detection tests for malaria need to be a ble to detect both species. We evaluated the new combined P. falciparum-P. vivax immunochromatographic test (ICT Malaria P,f/P.v.) in Radamata Primary Health Centre, Sumba, Indonesia, from February to May 1998 with 560 sympto matic adults and children with a presumptive clinical diagnosis of malaria, Blinded microscopy was used as the "gold standard," with all discordant an d 20% of concordant results cross-checked blindly. Only 50% of those with a presumptive clinical diagnosis of malaria were parasitemic. The ICT Malari a P,f/P,v immunochromatographic test was sensitive (95.5%) and specific (89 .8%) for the diagnosis of falciparum malaria, with a positive predictive va lue (PPV) and a negative predictive value (NPV) of 88.1 and 96.2%, respecti vely. HRP2. and panmalarial antigen line intensities were associated with p arasitemia density for both species, Although the specificity and NPV for t he diagnosis of vivax malaria were 94.8 and 98.2%, respectively, the overal l sensitivity (75%) and PPV (50%) for the diagnosis of vivax malaria were l ess than the desirable levels. The sensitivity for the diagnosis of P. viva x malaria,vas 96% with parasitemias of > 500/mu l but only 29% with parasit emias of < 500/mu l. Nevertheless, compared with the test with HRP2 alone, use of the combined antigen detection test would reduce the rate of undertr eatment from 14.7 to 3.6% for microscopy-positive patients, and this would be at the expense of only a modest increase in the rate of overtreatment of microscopy-negative patients from 7.1 to 15.4%. Cost remains a major obsta cle to widespread use in areas of endemicity.