Evaluation of a rapid diagnostic field test for malaria

Abstract

Between November 1999 and April 2000, a malariaoutbreak occurred in the state of La Guajira, Colombia; 5.687 cases were diagnosed -3,401 as P falciparum, 2,256 as P vivax and 30 as mixed infections. The conditions of location and case number were considered favorable for the application and evaluation of a rapid diagnostic field test. Malaria diagnosis obtained by the rapid immunocromatographic test (OptiMAL) and thick blood smear were compared in the municipalities of Dibulla, Manaure and Riohacha. The treatment of each patient was based on the rapid test result, but whenever the two methods disagreed, the thick bood smear results were given priority in decisions to modify the initial treatment. Two hundred thitiy-one finger-prick blood samples were processed. The general sensitivity and specificity of OptiMAL were 98.7% and 99.3%, respectively. The sensitivity and specificity for P falciparum were 98.1% and 76.9%. The sensitivity and specificity for F1 vivax were 90.9% and 100%. The concordance index was 0.98, the positive predictive value, 98.7% and the negative predictive value, 99.3%. These results suggest that the rapid immunocromatographic test (OptiMAL) is a reliable alternative for malaria diagnosis under circumstances where rnicroscopical diagnosis is not possible.