Dynamics of PfHRP2 antigen-based diagnostic tool efficiencies during high seasonal malaria transmission

Accurate malaria diagnosis remains critical for effective case management and surveillance, particularly in endemic regions where diagnostic reliability directly influences disease burden estimates. This study assessed the performance of a commonly used antigen-based rapid diagnostic test (RDT), comparing its accuracy with light microscopy and polymerase chain reaction (PCR). Five hundred and eleven (511) participants were enrolled for the study in a cross-sectional evaluation conducted within six districts in Ibadan, Southwest, Nigeria. Whole blood samples obtained from participants were subjected to diagnostic evaluation using a Pf HRP2 antigen-based rapid diagnostic test kit and microscopy. A subset of one hundred and fifty-three (153) samples was randomly selected for corrective and comparative diagnostic evaluation using conventional PCR. Cohen’s kappa coefficient was used to assess agreement between RDT, microscopy, and PCR beyond chance. On-field malaria prevalence using Pf HRP2 antigen-based diagnostics at presentation was 84.3%. Of the 153 RDT/PCR paired samples, three RDTs were invalid and excluded (all three were PCR positive), leaving 150 paired RDT/PCR results. Compared to PCR, RDT demonstrated a sensitivity of 92.7% (114/123; 95% CI 88.6–96.1) and specificity of 3.7% (1/27; 95% CI 0.7–18.3). The positive predictive value was 81.4% (95% CI 74.2–86.9) and the negative predictive value was 10.0% (95% CI 1.8–40.4), with an overall accuracy of 76.7%. Cohen’s kappa coefficient indicated slight agreement (κ = 0.02). Comparison of RDT with microscopy revealed high sensitivity of 93.3% but low specificity of 6.3%, with slight agreement (κ = 0.05) and exact McNemar significant discordance ( p < 0.052) between the pair. The Pf HRP2-based kit demonstrated measureable strength in field applicability and high sensitivity for malaria detection in high transmission settings. However, specificity estimates were limited by the small number of PCR-negative samples and should be attended with prudence. These findings support the continued use of Pf HRP2-based RDTs in routine clinical practice, while highlighting the importance of confirmatory testing where diagnostic uncertainty exists.