Quality Assurance (QA) Assessment for Malaria Rapid Diagnostic Test in Ngoma District, Eastern Province of Rwanda: A cross-sectional prospective study.

Background Currently, malaria rapid diagnostic tests (mRDTs) are increasingly used for the diagnosis of malaria, particularly in communities where microscopy-based diagnosis is not practical. However, the diagnostic accuracy of mRDTs performed by community health workers (CHWs) remains unknown. This study was conducted to determine the accuracy of mRDT results performed by CHWs in Ngoma district, eastern province of Rwanda. Method This was a cross sectional prospective study. A total of 420 blood samples of patients self-reported to CHWs for malaria diagnosis were collected and analyzed by CHWs using mRDT, and quality control tests were performed by using microscopy as a reference test. The study was conducted from 22 April to 08 July 2021. Results Among the 420 patients, 234 (55.71%) were females, and 186 (44.29%) were males. Malaria test positivity was 2.62% by using mRDT and 1.67% by using microscopic tests. The sensitivity and specificity of mRDT were 85.71% and 98.78%, respectively. The negative predictive value, positive predictive value and accuracy of mRDTs were 99.75%, 54.54% and 98.57%, respectively. The sensitivity of mRDT was below the WHO recommended sensitivity (>95%), although the specificity (98.78%) was within the WHO recommended specificity (>=90). There was substantial agreement between the mRDT and malaria microscopic test results, k=0.642. Conclusion mRDTs continue to be an appropriate choice for malaria diagnosis in the absence of microscopy.

Modelling the epidemiology of malaria and spread of HRP2-negative Plasmodium falciparum following the replacement of HRP2-detecting rapid diagnostic tests

Malaria rapid diagnostic tests (RDTs) are dominated by products which use histidine-rich protein 2 (HRP2) to detect Plasmodium falciparum. The emergence of parasites lacking the pfhrp2 gene can lead to high rates of false-negative results amongst these RDTs. One solution to restore the ability to correctly diagnose falciparum malaria is to switch to an RDT which is not solely reliant on HRP2. This study used an agent-based stochastic simulation model to investigate the impact on prevalence and transmission caused by switching the type of RDT used once false-negative rates reached pre-defined thresholds within the treatment-seeking symptomatic population. The results show that low transmission settings were the first to reach the false-negative switch threshold, and that lower thresholds were typically associated with better long-term outcomes. Changing the diagnostic RDT away from a HRP2-only RDT is predicted to restore the ability to correctly diagnose symptomatic malaria infections, but often did not lead to the extinction of HRP2-negative parasites from the population which continued to circulate in low density infections, or return to the parasite prevalence and transmission levels seen prior to the introduction of the HRP2-negative parasite. In contrast, failure to move away from HRP2-only RDTs leads to near fixation of these parasites in the population, and the inability to correctly diagnose symptomatic cases. Overall, these results suggest pfhrp2-deleted parasites are likely to become a significant component of P. falciparum parasite populations, and that long-term strategies are needed for diagnosis and surveillance which do not rely solely on HRP2.

Quality Assurance (QA) Assessment for Malaria Rapid Diagnostic Test in Ngoma District, Eastern Province of Rwanda: A cross-sectional prospective study

Background Currently, malaria rapid diagnostic tests (mRDTs) are increasingly used for diagnosis of malaria, particularly in community where microscopy-based diagnosis is not practical. However, the diagnostic accuracy of mRDTs performed by the community health workers (CHWs) remains unknown. This study was conducted to determine the accuracy of mRDT results performed by CHWs in Ngoma district, eastern province of Rwanda. Method This was a cross sectional prospective study. 420 blood samples of patients self-reported to CHWs for malaria diagnosis were collected and analyzed by CHWs using mRDT and quality control tests were performed by using microscopy as a reference test. The study was conducted from 22nd April to 08th July, 2021. Results Among the 420 patients, 234 (55.71%) were females and 186 (44.29%) were males. Malaria test positivity was 2.62% by using mRDT and 1.67% by using microscopic test. The sensitivity and specificity of mRDT were 85.71% and 98.78% respectively. Negative predictive value, positive predictive value and accuracy of mRDTs were 99.75%, 54.54% and 98.57% respectively. Sensitivity of mRDT was below the WHO recommended sensitivity (>95%) although the specificity (98.78%) was within the WHO recommended specificity (>=90). There was a substantial agreement between mRDT and malaria microscopic test results, k=0.642. Conclusion mRDTs continue to be an appropriate choice for malaria diagnosis in the absence of microscopy.

Quality Assurance (QA) Assessment for Malaria Rapid Diagnostic Test in Ngoma District, Eastern Province of Rwanda: A cross-sectional prospective study.

Background Currently, malaria rapid diagnostic tests (mRDTs) are increasingly used for diagnosis of malaria, particularly in community where microscopy-based diagnosis is not practical. However, the diagnostic accuracy of mRDTs performed by the community health workers (CHWs) remains unknown. This study was conducted to determine the accuracy of mRDT results performed by CHWs in Ngoma district, eastern province of Rwanda. Method This was a cross sectional prospective study. 420 blood samples of patients self-reported to CHWs for malaria diagnosis were collected and analyzed by CHWs using mRDT and quality control tests were performed by using microscopy as a reference test. The study was conducted from 22nd April to 08th July, 2021. Results Among the 420 patients, 234 (55.71%) were females and 186 (44.29%) were males. Malaria test positivity was 2.62% by using mRDT and 1.67% by using microscopic test. The sensitivity and specificity of mRDT were 85.71% and 98.78% respectively. Negative predictive value, positive predictive value and accuracy of mRDTs were 99.75%, 54.54% and 98.57% respectively. Sensitivity of mRDT was below the WHO recommended sensitivity (>95%) although the specificity (98.78%) was within the WHO recommended specificity (>=90). There was a substantial agreement between mRDT and malaria microscopic test results, k=0.642. Conclusion mRDTs continue to be an appropriate choice for malaria diagnosis in the absence of microscopy.

Impact of the Liberian National Community Health Assistant Program on Childhood Illness Treatment in Grand Bassa County, Liberia: A Difference-in-Differences Analysis of Population-Based Data

Liberia launched its National Community Health Assistant Program in 2016, which seeks to ensure that all people living 5 kilometers or farther from a health facility have access to trained, supplied, supervised, and paid community health workers (CHWs). This study aims to evaluate the impact of the national program following implementation in Grand Bassa County in 2018 using data from population-based surveys. We measured before-to-after changes in childhood treatment from qualified providers in a portion of the county that implemented in a first phase compared to those which had not yet implemented. We also assessed changes in whether children received oral rehydration therapy for diarrhea and malaria rapid diagnostic tests if they had a fever by a qualified provider (facility based or CHW). For these analyses, we used a difference-in-differences approach and adjusted for potential confounding using inverse probability of treatment weighting. We also assessed changes in the source from which care was received and examined changes by key dimensions of equity (distance from health facilities, maternal education, and household wealth). We found that treatment of childhood illness by a qualified provider increased by 60.3 percentage points (95%CI 44.7-76.0) more in intervention than comparison areas. Difference-in-differences for oral rehydration therapy and malaria rapid diagnostic tests were 37.6 (95%CI 19.5-55.8) and 38.5 (95%CI 19.9-57.0) percentage points, respectively. In intervention areas, treatment by a CHW increased from 0 to 81.6% and care from unqualified providers dropped. Increases in treatment by a qualified provider did not vary significantly by household wealth, remoteness, or maternal education. This evaluation found evidence that the Liberian National Community Health Assistant Program has increased access to effective treatment in rural Grand Bassa County. Improvements were approximately equal across three measured dimensions of marginalization.

Diagnostic Characteristics of Lactate Dehydrogenase on a Multiplex Assay for Malaria Detection Including the Zoonotic Parasite Plasmodium knowlesi

Plasmodium lactate dehydrogenase (pLDH) is a common target in malaria rapid diagnostic tests (RDTs). These commercial antibody capture assays target either Plasmodium falciparum–specific pLDH (PfLDH), P. vivax–specific pLDH (PvLDH), or a conserved epitope in all human malaria pLDH (PanLDH). However, there are no assays specifically targeting P. ovale, P. malariae or zoonotic parasites such as P. knowlesi and P. cynomolgi. A malaria multiplex array, carrying the specific antibody spots for PfLDH, PvLDH, and PanLDH has been previously developed. This study aimed to assess potential cross-reactivity between pLDH from various Plasmodium species and this array. We tested recombinant pLDH proteins, clinical samples for P. vivax, P. falciparum, P. ovale curtisi, and P. malariae; and in vitro cultured P. knowlesi and P. cynomolgi. P. ovale-specific pLDH (PoLDH) and P. malariae-specific pLDH (PmLDH) cross-reacted with the PfLDH and PanLDH spots. Plasmodium Knowlesi-specific pLDH (PkLDH) and P. cynomolgi-specific pLDH (PcLDH) cross-reacted with the PvLDH spot, but only PkLDH was recognized by the PanLDH spot. Plasmodium ovale and P. malariae can be differentiated from P. falciparum by the concentration ratios of PanLDH/PfLDH, which had mean (range) values of 4.56 (4.07–5.16) and 4.56 (3.43–6.54), respectively, whereas P. falciparum had a lower ratio of 1.12 (0.56–2.61). Plasmodium knowlesi had a similar PanLDH/PvLDH ratio value, with P. vivax having a mean value of 2.24 (1.37–2.79). The cross-reactivity pattern of pLDH can be a useful predictor to differentiate certain Plasmodium species. Cross-reactivity of the pLDH bands in RDTs requires further investigation.

Deletions of the Plasmodium falciparum histidine-rich protein 2/3 genes are common in field isolates from north-eastern Tanzania

Plasmodium falciparum parasites lacking histidine-rich protein 2 and 3 (pfhrp2/3) genes have been reported in several parts of the world. These deletions are known to compromise the effectiveness of HRP2-based malaria rapid diagnostic tests (HRP2-RDT). The National Malaria Control Programme (NMCP) in Tanzania adopted HRP2-RDTs as a routine tool for malaria diagnosis in 2009 replacing microscopy in many Health facilities. We investigated pfhrp2/3 deletions in 122 samples from two areas with diverse malaria transmission intensities in Northeastern Tanzania. Pfhrp2 deletion was confirmed in 1.6% of samples while pfhrp3 deletion was confirmed in 50% of samples. We did not find parasites with both pfhrp2 and pfhrp3 deletions among our samples. Results from this study highlight the need for systematic surveillance of pfhrp2/3 deletions in Tanzania to understand their prevalence and determine their impact on the performance of mRDT.

Secondary analysis of malaria rapid diagnostic tests from rounds 5–8 of WHO product testing with a focus on false-negative results

Despite the widespread use of malaria rapid diagnostic test (RDT) in clinical practice, there are a lot of challenges. We conducted a secondary analysis of 129 malaria RDT data from rounds 5–8 of the World Health Organization (WHO) product testing summary and discuss the causes of false-negative (FN) results with a focus on low parasite density, improper RDT storage, operation and interpretation, and plasmodium falciparum with a pfhrp2/3 gene deletion. The results demonstrated that the malaria RDTs currently commercially available might cause FN results in practice.

Plasmodium falciparum is evolving to escape malaria rapid diagnostic tests in Ethiopia

In Africa, most rapid diagnostic tests (RDTs) for falciparum malaria recognize histidine-rich protein 2 antigen. Plasmodium falciparum parasites lacking histidine-rich protein 2 (pfhrp2) and 3 (pfhrp3) genes escape detection by these RDTs, but it is not known whether these deletions confer sufficient selective advantage to drive rapid population expansion. By studying blood samples from a cohort of 12,572 participants enroled in a prospective, cross-sectional survey along Ethiopia’s borders with Eritrea, Sudan and South Sudan using RDTs, PCR, an ultrasensitive bead-based immunoassay for antigen detection and next-generation sequencing, we estimate that histidine-rich protein 2-based RDTs would miss 9.7% (95% confidence interval 8.5–11.1) of P. falciparum malaria cases owing to pfhrp2 deletion. We applied a molecular inversion probe-targeted deep sequencing approach to identify distinct subtelomeric deletion patterns and well-established pfhrp3 deletions and to uncover recent expansion of a singular pfhrp2 deletion in all regions sampled. We propose a model in which pfhrp3 deletions have arisen independently multiple times, followed by strong positive selection for pfhrp2 deletion owing to RDT-based test-and-treatment. Existing diagnostic strategies need to be urgently reconsidered in Ethiopia, and improved surveillance for pfhrp2 deletion is needed throughout the Horn of Africa.

Diagnostic Accuracy of CareStart™ Malaria HRP2 and SD Bioline Pf/PAN for Malaria in Febrile Outpatients in Varying Malaria Transmission Settings in Cameroon

Background: There was an increase in the number of malaria cases in Cameroon in 2018 that could reflect changes in provider practice, despite effective interventions. In this study, we assessed the diagnostic performance of two malaria rapid diagnostic tests (mRDTs) for diagnostic confirmation of suspected cases of malaria in public and private health facilities in two malaria transmission settings in Cameroon. Methods: We evaluated the diagnostic performance of CareStart pf and SD Bioline Pf/PAN mRDT and compared these parameters by RDT type and transmission setting. Nested PCR and blood film microscopy were used as references. The chi square test was used for independent sample comparisons, while the McNemar’s test was used to test for the dependence of categorical data in paired sample testing. A p < 0.05 was considered significant in all comparisons. The R (v.4.0.2) software was used for analyses. Results: A total of 1126 participants consented for the study in the four sites. The diagnostic accuracy of the CareStart Pf mRDT was 0.93.6% (0.911–0.961) in Yaoundé, 0.930% (0.90–0.960) in Ngounso, 0.84% (0.794–0.891) in St Vincent Catholic Hospital Dschang and 0.407 (0.345–0.468) in Dschang district hospital. For SD Bioline Pf/PAN the accuracy was 0.759 (0.738–0.846) for St Vincent Catholic Hospital Dschang and 0.426 (0.372–0.496) for the Dschang district hospital. The accuracy was slightly lower in each case but not statistically different when PCR was considered as the reference. The likelihood ratios of the positive and negative tests were high in the high transmission settings of Yaoundé (10.99 (6.24–19.35)) and Ngounso (14.40 (7.89–26.28)) compared to the low transmission settings of Dschang (0.71 (0.37–1.37)) and St Vincent Catholic hospital (7.37 (4.32−12.59)). There was a high degree of agreement between the tests in Yaoundé (Cohen’s Kappa: 0.85 ± 0.05 (0.7–0.95)) and Ngounso (Cohen’s Kappa: 0.86 ± 0.05 (0.74, 0.97)) and moderate agreement in St Vincent hospital Dschang (k: 0.58 ± 0.06 (0.44–0.71)) and poor agreement in the District Hospital Dschang (Cohen’s Kappa: −0.11 ± 0.05 (−0.21–0.01)). The diagnostic indicators of the SD Bioline Pf/PAN were slightly better than for CareStart Pf mRDT in St Vincent Catholic hospital Dschang, irrespective of the reference test. Conclusions: Publicly procured malaria rapid diagnostic tests in Cameroon have maintained high accuracy (91–94%) in the clinical diagnosis of malaria in high malaria transmission regions of Cameroon, although they failed to reach WHO standards. We observed an exception in the low transmission region of Dschang, West region, where the accuracy tended to be lower and variable between facilities located in this town. These results underscore the importance of the routine monitoring of the quality and performance of malaria RDTs in diverse settings in malaria endemic areas.