Evaluation of Diagnostic Accuracy of Rapid Malaria Tests Versus Microscopy in Secondary Healthcare Facilities in Nasarawa State

Accurate malaria diagnosis is a prerequisite for appropriate case management and prevention of over-treatment, which contributes to artemisinin resistance. This prospective diagnostic evaluation study compared the accuracy of WHO-prequalified rapid diagnostic tests (RDTs) with expert Giemsa-stained thick blood film microscopy for malaria diagnosis in patients presenting with fever at secondary healthcare facilities in Lafia, Nasarawa State, in the North Central geopolitical zone of Nigeria. A total of 320 febrile patients were enrolled, and all underwent both RDT and microscopy performed by trained laboratory scientists. Sensitivity, specificity, positive predictive value, and negative predictive value of RDTs were calculated using microscopy as the reference standard. RDT sensitivity was 94.8 percent and specificity was 87.3 percent. False-positive RDT results accounted for 12.7 percent of RDT-positive cases, predominantly in patients with recent malaria treatment due to antigen persistence. Parasite density below 200 parasites per microliter was associated with false-negative RDT results. Inter-laboratory concordance for microscopy between facility and reference laboratory readings was 89.4 percent. The study concludes that RDTs perform satisfactorily in high-transmission settings but recommends confirmatory microscopy for low-density positives, RDT reader training, and strengthened quality assurance for malaria diagnostics in Nasarawa State secondary facilities. Keywords: malaria RDT, microscopy, diagnostic accuracy, Nasarawa, fever management.