Comparative Study of Two Different Rapid Diagnostic Tests with Microscopy Method for Malaria Parasite Detection
Stella U. Ken-Ezihuo *
Department of Medical Laboratory Science, Rivers State University, Nkpolu-Oroworukwo, Port Harcourt, Nigeria.
Sigmund S. Itatat
Department of Medical Laboratory Science, Rivers State University, Nkpolu-Oroworukwo, Port Harcourt, Nigeria.
Ebirien-Agana S. Bartimaeus
Department of Medical Laboratory Science, Rivers State University, Nkpolu-Oroworukwo, Port Harcourt, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Introduction: Accurate rapid diagnosis is one of the most important steps in the effort to reduce morbidity and mortality of malaria. Blood-specific malaria rapid diagnostic tests (RDTs) are currently in use but reports on their sensitivity and specificity and comparison with the established blood film microscopy methods are dearth. The aim of the present study was to evaluate the performance characteristics of Nova and SD bioline RTDs and compare with microscopic method as a reference standard to detect the presence of malaria parasites in the blood.
Methods: A total of 100 subjects were conveniently selected from consented subjects attending out-patient Department of Rivers State University Teaching Hospital, Port Harcourt, and the samples were analyzed using blood film examined with Giemsa staining technique and Nova and SD bioline kits.
Results: Of the 100 samples examined, 57(57%) were positive for malaria parasite by light microscopy, 37(37%) were positive by Nova and 22 (22%) were positive by SD bioline. The sensitivity of the two RDTs used were found to be 54% for Nova and 30% for SD bioline, the specificity were 86% for Nova and 88% for SD bioline, the PPV for Nova was 83% and 77% for SD bioline while the NPV for Nova was 59% and 49% for SD bioline. Percentage positivity of 50.9% and 49.1% for males and females respectively means that both sexes are equally susceptible to malaria parasites. There was a slight increase in parasitaemia in females (1931±2801) than males (1139±2415) but these results were not statistically significant (P >.27).
Conclusion: The SD bioline showed a very poor sensitivity in contrast to Nova and light microscopy. Inspite of the relative advantages of RDTs, microscopy remains the best method of detecting malaria parasite and Nova should be preferred to other RDTs.
Keywords: Malaria, parasites, sensitivity, specificity, microscopy, blood film.