Diagnostic Performance of Hrp2 Based Diagnostic Test Kits and Frequency of Pfhrp2 Gene Deletion in Plasmodium falciparum Isolates of Osogbo, Southwestern Nigeria

Introduction: The introduction of P. falciparum encoded HRP-2 based malaria Rapid Diagnostic Test (RDT) kits is widely accepted in Nigeria and worldwide as a simplified form of diagnosis and a cheaper alternative to the microscopy technique (gold standard). However, deletion of Pfhrp2 gene contributes to false negative results and large number of such deletions has been reported in advanced countries thereby highlighting the importance of surveillance to detect such deletions in our local environment.

Methodology: Microscopy as well as RDT techniques (using Rapid malaria test kit: SD BIOLINE Malaria Ag P.f/Pv, South Korea) were carried out on the blood samples of three hundred and twenty-three (323) febrile subjects attending Ladoke Akintola University Teaching Hospital, Osogbo, Osun State Nigeria. PCR analysis was also conducted on 50 blood samples that were positive for microscopy but negative for RDT.

Results: The results from the study revealed that microscopy had a sensitivity of 99% and specificity of 99.2%. The RDT however had a sensitivity of 100% and a specificity of 60.1%. Fifty (50) samples that were positive for microscopy but negative for RDT were subjected to further PCR examination to detect the possible deletion of the Pfhrp-2 gene and the result revealed that the gene was present in 39 (78%) of the blood samples while remaining 11 (22%) samples lacked the gene which could possibly be the reason for the negative results obtained using the RDT kits.

Conclusion: This study provides evidence of low level of presence of Pfhrp-2 gene deletion of Plasmodium falciparum parasites in our healthcare facility setting in Osogbo, Nigeria.