Performance and Comparative Evaluation of a Novel Diagnostic Assay, Novaplex™ Malaria Assay Kit, against Routine Diagnostic Techniques in the detection of different Plasmodium spp. in Kenya
Authors: Karani Lewis , Thiong’o Kelvin , Otinga Maureen. A , Ombati Mary. N , Osano Maureen , Wangechi Lynette , Gesusu Nemrod , Aluvaala Eva , Onchieku Noah M. , Kimani Francis 
Published: November 2023

Background
Accurate and rapid diagnosis of malaria is crucial for effective treatment and control. More so, is the accurate species identification during treatment as it is essential in guiding treatment strategies across infections with different species of Plasmodium. This study aimed to evaluate the performance of a novel malaria diagnostic kit, Novaplex™ Malaria Assay, compared to routine diagnostic techniques currently in use, including microscopy, rapid diagnostic tests (RDTs), and polymerase chain reaction (PCR) in malaria diagnosis.
Methods
A total of 142 suspected malaria cases from Matayos, a malaria endemic zone in Kenya, were sampled. Whole blood samples were collected, Plasmodium parasite positivity and species identification were performed using microscopy, rapid diagnostic kits, the NovaplexTM malaria diagnostic assay, and qPCR. Sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV], accuracy, and agreement [Cohen’s kappa] were calculated to assess the diagnostic performance of the NovaplexTM kit against the rest of the techniques.
Results
Our analyses demonstrated that the NovaplexTM malaria assay yields a superior outcome compared to microscopy and mRDTs in terms of sensitivity, accuracy and NPV. The assay also showed an overall diagnostic agreement with qPCR. The kit showed an almost similar performance to qPCR in species identification. Using qPCR as the comparator “gold standard” test for the analysis, the sensitivity and specificity of the NovaplexTM assay was 95.5% and 87.5% respectively, while the sensitivity of microscopy and RDT was 63.7% and 61.5% respectively. The positive and negative predictive values were 99.2% and 53.9% respectively, for the NovaplexTM assay. This was in contrast to NPV values for microscopy and RDT which were 12.5% and 11.9% respectively. The accuracy of the NovaplexTM assay was recorded at 95.1% having a substantial agreement with qPCR at k = 0.642 [0.398–0.885]. For Microscopy and RDT, the level of accuracy was determined to be 65.5% and 63.4% respectively with a slight agreement to qPCR at k = 0.148 [0.047–0.248] and k = 0.136 [0.042–0.230] respectively.
Conclusion
The findings of this study demonstrate that the Novaplex assay outperformed microscopy and RDTs, showing comparable performance to qPCR in the identification and speciation of Plasmodium species in malaria infections. The high sensitivity, specificity, and overall agreement highlight the potential of the Novaplex assay as a reliable diagnostic tool for malaria. Implementation of this assay in routine clinical practice could improve the accuracy and efficiency of malaria diagnosis, leading to timely and appropriate treatment, enhanced surveillance, and effective control measures. Further validation studies and field evaluations are warranted to confirm the feasibility and cost effectiveness of this diagnostic assay in diverse malaria-endemic low resource settings