Glucose-6-Phosphate Dehydrogenase (G6PD) Measurement Using Biosensors by Community-Based Village Malaria Workers and Hospital Laboratory Staff in Cambodia: A Quantitative Study

Field evaluation of a novel semi-quantitative point-of-care diagnostic for G6PD deficiency in Indonesia

BACKGROUND

The WHO recommends routine testing of G6PD activity to guide radical cure in patients with Plasmodium vivax malaria. Females may have intermediate G6PD enzyme activity and to date, only complex diagnostics are able to reliably identify them. The semi-quantitative G6PD diagnostic "One Step G6PD Test" (Humasis, RoK; "RDT") is a lateral flow assay that can distinguish deficient, intermediate, and normal G6PD status and offers a simpler diagnostic alternative.

METHODS

G6PD status of participants enrolled in Malinau and Nunukan Regencies and the capital Jakarta was assessed with the RDT, and G6PD activity was measured in duplicate by reference spectrophotometry. The adjusted male median (AMM) of the spectrophotometry measurements was defined as 100% activity; 70% and 30% of the AMM were defined as thresholds for intermediate and deficient G6PD status, respectively. Results were compared to those derived from spectrophotometry at the clinically relevant G6PD activity thresholds of 30% and 70%.

RESULTS

Of the 161 participants enrolled, 10 (6.2%) were G6PD deficient and 12 (7.5%) had intermediate G6PD activity by spectrophotometry. At the 30% threshold, the sensitivity of the RDT was 10.0% (95%CI: 0.3-44.5%) with a specificity of 99.3% (95%CI: 96.4-100.0%); the positive predictive value was 50.0% (95%CI: 1.3-98.7%) and the negative predictive value 94.3% (95%CI: 89.5-97.4%). The corresponding figures at the 70% threshold were 22.7% (95%CI: 7.8-45.4%), 100.0% (95%CI: 97.4-100.0%), 100.0% (95%CI: 47.8-100.0%) and 89.1% (95%CI: 83.1-93.5%), respectively.

CONCLUSION

While there is a dire need for an easy-to-use, economical, semi-quantitative diagnostic for the point of care, the observed performance of the "One Step G6PD Test" in its current form was insufficient to guide antimalarial treatment.

Progress towards malaria elimination in the Greater Mekong Subregion: perspectives from the World Health Organization

Malaria remains a global health challenge, disproportionately affecting vulnerable communities. Despite substantial progress, the emergence of anti-malarial drug resistance poses a constant threat. The Greater Mekong Subregion (GMS), which includes Cambodia, China's Yunnan province, Lao People's Democratic Republic, Myanmar, Thailand, and Viet Nam has been the epicentre for the emergence of resistance to successive generations of anti-malarial therapies. From the perspective of the World Health Organization (WHO), this article considers the collaborative efforts in the GMS, to contain Plasmodium falciparum artemisinin partial resistance and multi-drug resistance and to advance malaria elimination. The emergence of artemisinin partial resistance in the GMS necessitated urgent action and regional collaboration resulting in the Strategy for Malaria Elimination in the Greater Mekong Subregion (2015-2030), advocating for accelerated malaria elimination interventions tailored to country needs, co-ordinated and supported by the WHO Mekong malaria elimination programme. The strategy has delivered substantial reductions in malaria across all GMS countries, with a 77% reduction in malaria cases and a 97% reduction in malaria deaths across the GMS between 2012 and 2022. Notably, China was certified malaria-free by WHO in 2021. Countries' ownership and accountability have been pivotal, with each GMS country outlining its priorities in strategic and annual work plans. The development of strong networks for anti-malarial drug resistance surveillance and epidemiological surveillance was essential. Harmonization of policies and guidelines enhanced collaboration, ensuring that activities were driven by evidence. Challenges persist, particularly in Myanmar, where security concerns have limited recent progress, though an intensification and acceleration plan aims to regain momentum. Barriers to implementation can slow progress and continuing innovation is needed. Accessing mobile and migrant populations is key to addressing remaining transmission foci, requiring effective cross-border collaboration. In conclusion, the GMS has made significant progress towards malaria elimination, particularly in the east where several countries are close to P. falciparum elimination. New and persisting challenges require sustained efforts and continued close collaboration. The GMS countries have repeatedly risen to every obstacle presented, and now is the time to re-double efforts and achieve the 2030 goal of malaria elimination for the region.

Field assessment of the operating procedures of a semi-quantitative G6PD Biosensor to improve repeatability of routine testing

In remote communities, diagnosis of G6PD deficiency is challenging. We assessed the impact of modified test procedures and delayed testing for the point-of-care diagnostic STANDARD G6PD (SDBiosensor, RoK), and evaluated recommended cut-offs. We tested capillary blood from fingerpricks (Standard Method) and a microtainer (BD, USA; Method 1), venous blood from a vacutainer (BD, USA; Method 2), varied sample application methods (Methods 3), and used micropipettes rather than the test's single-use pipette (Method 4). Repeatability was assessed by comparing median differences between paired measurements. All methods were tested 20 times under laboratory conditions on three volunteers. The Standard Method and the method with best repeatability were tested in Indonesia and Nepal. In Indonesia 60 participants were tested in duplicate by both methods, in Nepal 120 participants were tested in duplicate by either method. The adjusted male median (AMM) of the Biosensor Standard Method readings was defined as 100% activity. In Indonesia, the difference between paired readings of the Standard and modified methods was compared to assess the impact of delayed testing. In the pilot study repeatability didn't differ significantly (p = 0.381); Method 3 showed lowest variability. One Nepalese participant had <30% activity, one Indonesian and 10 Nepalese participants had intermediate activity (≥30% to <70% activity). Repeatability didn't differ significantly in Indonesia (Standard: 0.2U/gHb [IQR: 0.1-0.4]; Method 3: 0.3U/gHb [IQR: 0.1-0.5]; p = 0.425) or Nepal (Standard: 0.4U/gHb [IQR: 0.2-0.6]; Method 3: 0.3U/gHb [IQR: 0.1-0.6]; p = 0.330). Median G6PD measurements by Method 3 were 0.4U/gHb (IQR: -0.2 to 0.7, p = 0.005) higher after a 5-hour delay compared to the Standard Method. The definition of 100% activity by the Standard Method matched the manufacturer-recommended cut-off for 70% activity. We couldn't improve repeatability. Delays of up to 5 hours didn't result in a clinically relevant difference in measured G6PD activity. The manufacturer's recommended cut-off for intermediate deficiency is conservative.

Expanding the roles of community health workers to sustain programmes during malaria elimination: a meeting report on operational research in Southeast Asia

In Southeast Asia malaria elimination is targeted by 2030. Cambodia aims to achieve this by 2025, driven in large part by the urgent need to control the spread of artemisinin-resistant falciparum malaria infections. Rapid elimination depends on sustaining early access to diagnosis and effective treatment. In much of Cambodia, rapid elimination will rely on a village malaria worker (VMW) network. Yet as malaria declines and is no longer a common cause of febrile illness, VMWs may become less popular with febrile patients, as VMWs do not diagnose or treat other conditions at present. There is a risk that VMWs become inactive and malaria rebounds before the complete interruption of transmission is achieved.During 2021-23 a large-scale operational research study was conducted in western Cambodia to explore how a VMW network could be sustained by including health activities that cover non-malarial illnesses to encourage febrile patients to continue to attend. 105 VMWs received new rapid diagnostic tests (including dengue antigen-antibody and combined malaria/C-reactive protein tests), were trained in electronic data collection, and attended health education packages on hygiene and sanitation, disease surveillance and first aid, management of mild illness, and vaccination and antenatal care.In August 2023 the National Malaria Control Programme of Cambodia convened a stakeholder meeting in Battambang, Cambodia. Findings from the study were reviewed in the context of current malaria elimination strategies. The discussions informed policy options to sustain the relevance of the VMW network in Cambodia, and the potential for its integration with other health worker networks. This expansion could ensure VMWs remain active and relevant until malaria elimination is accomplished.

Plasmodium vivax Malaria and G6PD Testing

Early malaria investigators were certainly correct in classifying the species falciparum and the species vivax as belonging to the same genus, Plasmodium [...].

A Review of the Current Status of G6PD Deficiency Testing to Guide Radical Cure Treatment for Vivax Malaria

Plasmodium vivax malaria continues to cause a significant burden of disease in the Asia-Pacific, the Horn of Africa, and the Americas. In addition to schizontocidal treatment, the 8-aminoquinoline drugs are crucial for the complete removal of the parasite from the human host (radical cure). While well tolerated in most recipients, 8-aminoquinolines can cause severe haemolysis in glucose-6-phosphate dehydrogenase (G6PD) deficient patients. G6PD deficiency is one of the most common enzymopathies worldwide; therefore, the WHO recommends routine testing to guide 8-aminoquinoline based treatment for vivax malaria whenever possible. In practice, this is not yet implemented in most malaria endemic countries. This review provides an update of the characteristics of the most used G6PD diagnostics. We describe the current state of policy and implementation of routine point-of-care G6PD testing in malaria endemic countries and highlight key knowledge gaps that hinder broader implementation. Identified challenges include optimal training of health facility staff on point-of-care diagnostics, quality control of novel G6PD diagnostics, and culturally appropriate information and communication with affected communities around G6PD deficiency and implications for treatment.