Performance of PfHRP2 and PfPLDH Rapid Diagnostics Test for Diagnosis of Plasmodium falciparum in Assosa Zone, Northwest Ethiopia

Abstract

Background Malaria is a life-threatening infectious disease particularly due to Plasmodium falciparum (P.falciparum ). Plasmodium falciparum Histidine-Rich Protein 2 (PfHRP-2) and Plasmodium falciparum specific Lactate Dehydrogenase (PfPLDH) based rapid diagnostic test are commonly used for malaria diagnosis in malaria endemic countries where microscopic examination is scarce. However, there is limited information on the performance of malaria RDT in rural and semi urban area of Assosa zone, Northwest Ethiopia. Thus, the aim of this study is to determine the performance of PfHRP2 and PfPLDH RDT for diagnosis of falciparum malaria against microscopy as reference method. Methods Health-facility based cross-sectional study design was conducted in Assosa zone, Northwest Ethiopia from November to December 2018. A total of four hundred and six malaria-suspected participants attending Bambasi, Sherkole, Kurmuk and Assosa health-centers were tested. Finger-prick blood samples were collected for microscopy blood film preparation, RDTs and molecular diagnosis. Statistical analyses were performed using SPSS version 20. Results Of the total study participants, 26.4% (107/406) were microscope confirmed P. falciparum positive. Using PfHRP2 and PfPLDH RDT, 30.3% (123/406) and 24.1% (98/406) were positive for P. falciparum, respectively. The sensitivity of PfHRP2 and PfPLDH was 96% and 89%, respectively, against microscope. The corresponding specificity rates of PfHRP2 and PfPLDH were 93% and 99%, respectively. Similarly, positive predictive value (PPV) and negative predictive value of PfHRP2 and PfPLDH RDT were 84%, 97%, 99% and 96%, respectively. There was an agreement between RDTs (PfPLDH and PfHRP2) and reference microscopy method with a kappa value of 0.86 and 0.90, respectively. Compared to qPCR, the specificity of PfHRP2 (93%) and PfPLDH RDT (98%) were high, though the respective sensitivity of PfHRP2(77%) and PfPLDH RDT(70%) were low. Conclusion PfHRP2 and PfPLDH showed reasonable agreement in detecting P. falciparum infections. Hence, currently used national malaria RDT kit can be continue to be used in certain malaria endemic areas in Ethiopia. However, Continuous monitoring the performance of PfHRP-2 RDT associated with false negative results is important to consider an alternative malaria RDT like PfPLDH RDT to support control and elimination of malaria in Ethiopia