Microscopy and CareStart™ HRP2/pLDH (Pf/PAN) Rapid Diagnostic Testing for Malaria among Symptomatic Patients at Federal Medical Centre Keffi, Nasarawa State, Nigeria
Edward Rosemary *
Department of Medical Laboratory Sciences, College of Health Sciences, Igbinedion University, Okada, Nigeria and Department of Medical Laboratory Services, Federal Medical Centre, Keffi, PMB 1004, Keffi, Nasarawa State, Nigeria.
Ugbomoiko Daniel Ohilebo
Department of Medical Laboratory Sciences, College of Health Sciences, Igbinedion University, Okada, Nigeria.
Nwakaego Mercy Ezeunala
Department of Microbiology and Biotechnology, National Institute for Pharmaceutical Research and Development (NIPRD), Idu, Abuja, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Microscopy and malaria rapid diagnostic tests (mRDTs) are routinely used to identify Plasmodium infection. Locally generated paired-test data can help characterise agreement between diagnostic approaches in symptomatic hospital attendees.
Objective: To estimate malaria test positivity and compare the CareStart™ HRP2/pLDH (Pf/PAN) combination mRDT with light microscopy among symptomatic patients attending Federal Medical Centre Keffi, Nasarawa State, Nigeria.
Methods: In this hospital-based cross-sectional study, venous blood specimens from 500 participants enrolled between August 2024 and September 2025 were examined by Giemsa-stained microscopy and the CareStart™ combination mRDT. Diagnostic accuracy indices were calculated with microscopy as the comparator, and agreement was assessed using Cohen’s kappa. Age- and sex-stratified test positivity and results across microscopy-reported parasite-density categories were summarised.
Results: Microscopy identified Plasmodium infection in 128/500 (25.6%) participants, compared with 121/500 (24.2%) by mRDT. Relative to microscopy, there were 121 true-positive, 372 true-negative, seven false-negative, and no false-positive mRDT results. Sensitivity was 94.5% (95% confidence interval [CI]: 89.1–97.8%), specificity 100.0% (95% CI: 99.0–100.0%), positive predictive value 100.0%, negative predictive value 98.2%, and overall agreement 98.6% (Cohen’s κ = 0.963). Microscopy positivity was highest in the 11–15-year group (27/46; 58.7%). Sensitivity across the four recorded microscopy-density grades was 92.9%, 93.0%, 100.0%, and 94.4%, respectively. All microscopy-identified infections were classified as P. falciparum.
Conclusion: The CareStart™ combination mRDT showed high agreement with microscopy in this selected symptomatic hospital population but missed seven microscopy-positive results. The findings describe performance relative to an imperfect comparator and do not establish community prevalence or the mechanisms of individual discordant results.
Keywords: Malaria, Plasmodium falciparum, microscopy, rapid diagnostic test, HRP2, pLDH, diagnostic agreement, Nigeria