Comparative Diagnosis of Falciparum Malaria Infections by Microscopy, Two RDTs, and Nested PCR in the Three States of North-Western Nigeria

Abstract

One of the most pronounced problems in controlling the morbidity and mortality caused by malaria is limited access to effective diagnosis. Microscopy remains the gold standard for malaria diagnosis, but it is labor intensive, requires significant skills and time. Thus, this study was conducted in search of any prompt, reliable, and good alternative of microscopy, when it is not available. A total of 540 patients in the three states of north-western Nigeria were prospectively enrolled to compare the performance of the Pf-HRP2 rapid diagnostic tests (RDTs), Pf/PAN-pLDH RDTs, and nested polymerase chain reaction (nPCR) with gold standard expert microscopy by 2x2 contingency tables, using standard formulae. For P. falciparum diagnosis, the sensitivity (Sn) and specificity (Sp) of Pf-HRP2 RDTs was 82% and 95%, while the Sn and Sp of Pf/PAN-pLDH RDTs (line 1) was 75% and 99%. Both Sn and Sp of nPCR were excellent with 98% and 100% respectively. The sensitivities of RDTs in this study were not optimal for P. falciparum diagnosis. Although, nPCR can be a good alternative of microscopy but the cost, qualitative nature and urgency of obtaining results with suspected malaria limits its use in routine clinical practice. Thus, microscopy should remain the diagnostic test of choice for malaria in this region.

Key word: falciparum malaria, microscopy, RDTs, nPCR, Nigeria