Diagnostic Performance of NxTek™ Eliminate Malaria Pf test for the detection of Plasmodium falciparum in school children with asymptomatic malaria

Abdissa Biruksew (PhD Candidate); Ashenafi Demeke (Mr.); Prof. Zewdie Birhanu (PhD); Estifanos Kebede (Mr.); Dr. Lemu Golassa (PhD, Associate professor); Dr. Evans Mantiri Mathebula; Prof. Delenasaw Yewhalaw(PhD)

EPHA Conference Systems, 34th EPHA Annual Conference

Abdissa Biruksew (PhD Candidate), Ashenafi Demeke (Mr.), Prof. Zewdie Birhanu (PhD), Estifanos Kebede (Mr.), Dr. Lemu Golassa (PhD, Associate professor), Dr. Evans Mantiri Mathebula, Prof. Delenasaw Yewhalaw(PhD)

Last modified: 2023-03-09

Abstract

Background: One of the major roadblocks to the falciparum malaria elimination program is the presence of significant number of asymptomatic malaria-infected individuals in endemic areas. Identifying and targeting such reservoirs of infections is critical to interrupting transmission and enhancing elimination efforts. The NxTek^TM Eliminate Malaria Pf test is a highly sensitive rapid diagnostic test (hsRDT) for the detection of HRP-2. However, knowledge gaps exist in Ethiopia on the diagnostic performance of hsRDT in asymptomatic individuals.

Objective: To evaluate the diagnostic performance of NxTek^TM Eliminate Malaria Ag Pf for the detection of P. falciparum in asymptomatic school children in low malaria transmission setting in Ethiopia.

Methods: A school-based cross-sectional study was conducted from September 2021 to January 2022 on 1002 apparently healthy school children (aged 6 to 15 years). Finger-pricked whole blood samples were collected for microscopy, hsRDT, SD Bioline Malaria Ag Pf/P. v (cRDT), and QuantStudio^TM3 Real-Time PCR system (qPCR). The hsRDT was compared with cRDT and microscopy. The qPCR was used as a reference method.

Results: The prevalence of P. falciparum was 1.5%, 2.2%. 2.2% and 4.5%, by microscopy, hsRDT, cRDT and qPCR, respectively. The sensitivity and specificity of hsRDT and cRDT was 100% and 99.28%, respectively, compared to microscopy. Both RDTs and microscopy showed strong agreement with a kappa score of 0.81 and test accuracy of 99.4%. When qPCR was used as a reference, the sensitivity and specificity of hsRDT/cRDT were 48.89% and 100%, respectively, while the PPV and NPV were 100% and 70.5%, respectively with a kappa value of 0.64. There was an agreement between the malaria RDTs and the qPCR with a test accuracy of 74.4%. The sensitivity and specificity of microscopy were 33.7% and 100%, respectively. In this study, there was no difference in the performance metrics of RDTs.

Conclusions: The hsRDT showed superior sensitivity and provided accurate detection of falciparum than microscopy in asymptomatic school children. It can be integrated into the malaria diagnostic algorithm of the Federal Ministry of Health of Ethiopia (FMoH) and used as a point-of-care test for asymptomatic falciparum malaria infected population. Further study on the possible HRP2/3 gene deletions for likely causes of false negative results is required