Prevalence of Plasmodium Parasitaemia and Diagnostic Accuracy of Malaria Rapid Diagnostic Tests in Sabongidda-Ora, Edo State, Nigeria

Abstract

Accurate, timely diagnosis underpins effective case management wherever malaria is endemic, yet many rural health facilities in sub-Saharan Africa lack the trained personnel and equipment that microscopy requires. Rapid diagnostic tests (RDTs) offer an alternative, but their field performance can vary by brand, storage conditions, and the population tested. We evaluated a Histidine-Rich Protein 2 (HRP2)-based RDT against thick blood-film microscopy in 100 febrile adults attending the Michael Imoudu Comprehensive Health Care Centre in Sabongidda-Ora, Edo State, Nigeria, over May–June 2025, a period of peak transmission — a rural setting for which diagnostic performance data have not previously been reported. Plasmodium parasitaemia was detected in 59 of the 100 participants by RDT and in 56 of the 100 participants by microscopy. Taking microscopy as the reference standard, the RDT missed none of the 56 confirmed cases (sensitivity 100%) and correctly cleared 41 of 44 uninfected participants (specificity 93.2%), yielding a positive predictive value of 94.9%, a negative predictive value of 100%, and an overall agreement of 97% with microscopy. These findings indicate that, in a high-transmission, symptomatic adult population, HRP2-based RDTs can detect malaria as reliably as microscopy at the point of care. Given that specificity fell short of 100%, we recommend that microscopy be retained alongside RDTs for confirmatory testing and surveillance, particularly where treatment decisions carry downstream costs. Because these results come from a single facility during one transmission season, their generalisability to low-transmission or asymptomatic populations should be tested in further studies.