[Evaluation of two rapid diagnostic tests, NOW ICT Malaria Pf/Pv and OptiMAL, for diagnosis of malaria]

Abstract

Introduction: To increase the accessibility of malaria diagnosis, the Instituto Nacional de Salud de Colombia undertook a field trial to evaluate the sensitivity and specificity of two rapid diagnostic tests.

Objective: The sensitivity, specificity and concordance was compared for two rapid diagnostic tests for malaria, NOW ICT Malaria Pf/Pv and OptiMAL.

Materials and methods: A descriptive and concordance study was performed with 214 patients in the southwestern coastal city of Tumaco, Colombia, each of whom presented at least one of the symptoms of the classical malaria triad. Two strategies were applied for patient recruitment-one by passive search and a second through local health brigades.

Results: NOW ICT showed a general sensitivity of 98.4% (95%CI: 90.3-99.9), and a general specificity of 98.0% (95%CI: 93.9-99.5). For Plasmodium falciparum, the sensitivity was 98.2% (95%CI: 89.4-99.9) and the specificity 98.1% (95%CI: 94.1-99.5). The sensitivity was lower (80.0%) when parasitemia ranged from 200 to 4,000 parasites/microl. The sensitivity and specificity of the NOW ICT for P. vivax malaria were 100%. The sensitivity for this test was not affected for the established ranges of parasitemia for P. vivax. The overall figures for OptiMAL were 95.2% (95%CI: 85.8-98.8) sensitivity and 99.3% (95%CI: 95.8-100.0) specificity. For P. falciparum malaria OptiMAL showed 94.7% (95%CI: 84.5-98.6) sensitivity and 99.4% (95%CI: 96.0-100.0) specificity. The sensitivity was lower (60.0%) when samples with 200-4,000 parasites/microl were tested. For P. vivax, OptiMAL presented a 66.7% (95%CI: 24.1-94.0) sensitivity, which diminished to 50% with a parasitemia between 300-2.500 parasites/microL.

Conclusions: Good results for sensitivity and specificity were obtained for malaria diagnosis using NOW ICT and OptiMAL, with NOW ICT showing higher sensitivity and specificity values than OptiMAL.