Abstract:
Background: Rapid diagnostic test (RDT) plays an essential role for prompt diagnosis of malaria
in settings where using microscopy is not feasible. However, there is an increasing concern that
Plasmodium falciparum histidine rich protein (PfHRP) gene deletions could impede the
performance of the commonly used RDTs, resulting in a false negative diagnosis. This suggests
the need to develop and evaluate new RDT kits to overcome such challenges.
Objective: To evaluate the diagnostic performance of Biocredit RDTs Pf(pLDH/HRP2) and
Pf/Pv(pLDH/pLDH) for detection of Plasmodium species and determine the prevalence of PfHRP
2/3 gene deletions among febrile patients at Maksegnit Health Center (MHC), northwest Ethiopia.
Methods: A health facility-based cross-sectional study was conducted from September to
December 2021 in 384 malaria suspected febrile study subjects at MHC. Finger-prick blood
samples were collected for malaria diagnosis using microscopy, RDTs and Quantitative
Polymerase Chain Reaction (qPCR). Sensitivity, specificity, positive and negative predictive
values of the RDTs were determined by comparing with the gold standard microscopy and qPCR
Digital Polymerase Chain Reaction (dPCR) was used to detect PfHRP 2/3 gene deletion.
Results: The prevalence of malaria among febrile patients was 69.3%, 67.2%, 42.2% and 71.4%
by microscopy, Biocredit RDT Pf/Pv (pLDH/pLDH), SD Bioline RDT and qPCR, respectively.
By taking microscopy as a reference, the Biocredit Pf/Pv (pLDH/pLDH) RDT had sensitivity and
specificity of 97.9% and 97.4% for P. falciparum and 94.5% and 97.5% for P. vivax, respectively.
The Biocredit Pf (pLDH/HRP2) RDT had sensitivity and specificity of 97.4% and 97.5%. In
contrast, SD Bioline RDT had sensitivity and specificity of 51.3% and 93.2% for P. falciparum,
and 86.3% and 96.5% for P. vivax, respectively. By taking qPCR as a reference, the sensitivity
and specificity of Biocredit Pf/Pv (pLDH/pLDH) were 95.5% and 96.4% for P. falciparum, and
90.8% and 99.1% for P. vivax, respectively. The Biocredit Pf (pLDH/pHRP2) RDT had sensitivity
and specificity of 94.9% and 97.4%, respectively, whereas the SD Bioline RDT had sensitivity
and specificity of 50.0% and 96.5% for P. falciparum, and 83.0% and 96.5% for P. vivax,
respectively. Out of 99 SD Bioline RDT negative samples, Pfhrp2 and Pfhrp3 exon 2 gene
deletions were observed in 23.2% (46/198) and 27.7% (55/198) of the PCR-positive samples,
II
respectively. Double deletions in pfhrp2 and pfhrp3 were detected in 13.1% (26/198) of the PCR
positive samples.
Conclusion: The sensitivity and specificity of Biochredit RDTs kits documented in this study
comply with the WHO limit of detection for routine diagnosis of clinical malaria, with more
reliable diagnostic performance compared to the conventional (SD Bioline) RDT. This study
confirms the presence of 13.1% of pfhrp2/3 gene deletions So, we should consider alternative
diagnostic tool like Pf-pLDH in the study area. Further nationwide survey on the prevalence of hrp
2/3 gene deletion is crucial.
