Impact of Enzymatically Extracted High Molecular Weight Fucoidan on Lipopolysaccharide-Induced Endothelial Activation and Leukocyte Adhesion.

The endothelial cell lining creates an interface between circulating blood and adjoining tissue and forms one of the most critical barriers and targets for therapeutical intervention. Recent studies suggest that fucoidans, sulfated and fucose-rich polysaccharides from brown seaweed, show multiple promising biological effects, including anti-inflammatory properties. However, their biological activity is determined by chemical characteristics such as molecular weight, sulfation degree, and molecular structure, which vary depending on the source, species, and harvesting and isolation method. In this study, we investigated the impact of high molecular weight (HMW) fucoidan extract on endothelial cell activation and interaction with primary monocytes (MNCs) in lipopolysaccharide (LPS)-induced inflammation. Gentle enzyme-assisted extraction combined with fractionation by ion exchange chromatography resulted in well-defined and pure fucoidan fractions. FE_F3, with a molecular weight ranging from 110 to 800 kDa and a sulfate content of 39%, was chosen for further investigation of its anti-inflammatory potential. We observed that along with higher purity of fucoidan fractions, the inflammatory response in endothelial mono- and co-cultures with MNCs was reduced in a dose-dependent manner when testing two different concentrations. This was demonstrated by a decrease in IL-6 and ICAM-1 on gene and protein levels and a reduced gene expression of TLR-4, GSK3ß and NF-kB. Expression of selectins and, consequently, the adhesion of monocytes to the endothelial monolayer was reduced after fucoidan treatment. These data indicate that the anti-inflammatory effect of fucoidans increases with their purity and suggest that fucoidans might be useful in limiting the inflammatory response of endothelial cells in cases of LPS-induced bacterial infection.

Structural Characterization and Cytotoxic Activity Evaluation of Ulvan Polysaccharides Extracted from the Green Algae Ulva papenfussii.

Ulvan, a sulfated heteropolysaccharide with structural and functional properties of interest for various uses, was extracted from the green seaweed Ulva papenfussii. U. papenfussii is an unexplored Ulva species found in the South China Sea along the central coast of Vietnam. Based on dry weight, the ulvan yield was ~15% (w/w) and the ulvan had a sulfate content of 13.4 wt%. The compositional constitution encompassed L-Rhamnose (Rhap), D-Xylose (Xylp), D-Glucuronic acid (GlcAp), L-Iduronic acid (IdoAp), D-Galactose (Galp), and D-Glucose (Glcp) with a molar ratio of 1:0.19:0.35:0.52:0.05:0.11, respectively. The structure of ulvan was determined using High-Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FT-IR), and Nuclear Magnetic Resonance spectroscopy (NMR) methods. The results showed that the extracted ulvan comprised a mixture of two different structural forms, namely ("A3s") with the repeating disaccharide [→4)-ß-D-GlcAp-(1→4)-α-L-Rhap 3S-(1→]n, and ("B3s") with the repeating disaccharide [→4)-α-L-IdoAp-(1→4)-α-L-Rhap 3S(1→]n. The relative abundance of A3s, and B3s was 1:1.5, respectively. The potential anticarcinogenic attributes of ulvan were evaluated against a trilogy of human cancer cell lineages. Concomitantly, Quantitative Structure-Activity Relationship (QSAR) modeling was also conducted to predict potential adverse reactions stemming from pharmacological interactions. The ulvan showed significant antitumor growth activity against hepatocellular carcinoma (IC50 ≈ 90 µg/mL), human breast cancer cells (IC50 ≈ 85 µg/mL), and cervical cancer cells (IC50 ≈ 67 µg/mL). The QSAR models demonstrated acceptable predictive power, and seven toxicity indications confirmed the safety of ulvan, warranting its candidacy for further in vivo testing and applications as a biologically active pharmaceutical source for human disease treatment.

Why using bed nets is a challenge among minority populations in Central Vietnam.

BACKGROUND: Despite freely distributed insecticide-treated nets (ITNs) and health information campaigns to increase their use among populations at risk, malaria transmission persists in forested areas in Vietnam, especially among ethnic minority communities. A mixed-methods study was conducted in four villages of Ca Dong and M'nong ethnicity in Central Vietnam between 2009 and 2011 to assess factors limiting the uptake of ITNs. METHODS: The mixed-methods research design consisted of a qualitative study to explore the context and barriers to ITN use, and a cross-sectional household survey (n = 141) to quantify factors for limited and appropriate net use. RESULTS: The Ca Dong and M'nong's livelihood was dependent on swidden farming in the forest. Poverty-related factors, including the lack of beds, blankets, the practice of sleeping around the kitchen fire and deteriorated ITNs due to open housing structures, were reasons for alternative and non-use of ITNs. When household members stayed overnight in plot huts at fields, ITNs were even more unavailable and easily deteriorated. 72.5% of households reported having received one net for every two persons, and 82.2% of participants reported to have used ITNs the night before the survey. However, only 18.4% of participants were estimated to be effectively protected by ITNs after accounting for the availability of torn ITNs and the way ITNs were used, for example as blankets, at both village and fields. Multi-variable logistic regression showed the effect of four significant factors for appropriate ITN use: i) being female (AOR = 8.08; p = 0.009); ii) aware of mosquito bites as the sole cause of malaria (AOR = 7.43; p = 0.008); iii) not sleeping around the kitchen fire (AOR = 24.57; p = 0.001); and iv) having sufficient number of ITNs in the household (AOR = 21.69; p = 0.001). CONCLUSION: This study showed how social factors rooted in poverty and swidden agriculture limited the effective use of ITNs, despite high coverage, among ethnic minority populations in Central Vietnam. An in-depth understanding of the local context is essential to develop specific indicators for measuring ITN use.

The Endo-α(1,3)-Fucoidanase Mef2 Releases Uniquely Branched Oligosaccharides from Saccharina latissima Fucoidans.

Fucoidans are complex bioactive sulfated fucosyl-polysaccharides primarily found in brown macroalgae. Endo-fucoidanases catalyze the specific hydrolysis of α-L-fucosyl linkages in fucoidans and can be utilized to tailor-make fucoidan oligosaccharides and elucidate new structural details of fucoidans. In this study, an endo-α(1,3)-fucoidanase encoding gene, Mef2, from the marine bacterium Muricauda eckloniae, was cloned, and the Mef2 protein was functionally characterized. Based on the primary sequence, Mef2 was suggested to belong to the glycosyl hydrolase family 107 (GH107) in the Carbohydrate Active enZyme database (CAZy). The Mef2 fucoidanase showed maximal activity at pH 8 and 35 °C, although it could tolerate temperatures up to 50 °C. Ca2+ was shown to increase the melting temperature from 38 to 44 °C and was furthermore required for optimal activity of Mef2. The substrate specificity of Mef2 was investigated, and Fourier transform infrared spectroscopy (FTIR) was used to determine the enzymatic activity (Units per µM enzyme: Uf/µM) of Mef2 on two structurally different fucoidans, showing an activity of 1.2 × 10-3 Uf/µM and 3.6 × 10-3 Uf/µM on fucoidans from Fucus evanescens and Saccharina latissima, respectively. Interestingly, Mef2 was identified as the first described fucoidanase active on fucoidans from S. latissima. The fucoidan oligosaccharides released by Mef2 consisted of a backbone of α(1,3)-linked fucosyl residues with unique and novel α(1,4)-linked fucosyl branches, not previously identified in fucoidans from S. latissima.

In search of the last malaria cases: ethnographic methods for community and private-sector engagement in malaria elimination in Vietnam, Laos, and Cambodia.

BACKGROUND: Despite significant strides made in reducing malaria morbidity and mortality in the Greater Mekong Subregion, malaria transmission continues amongst the most 'hard-to-reach', such as forest-goers and mobile and migrant populations, who face access obstacles to malaria diagnosis and treatment. As such, regional malaria elimination strategies endeavour to incorporate the private sector and local communities in improving surveillance and detection of the last malaria cases in remote forested areas. The question remains, however, whether such strategies can reach these hard-to-reach populations and effectively reduce their disproportionate burden of malaria. This paper evaluates the strategy of community and private sector engagement in a malaria elimination project in Vietnam, Laos, and Cambodia. METHODS: Ethnographic research, incorporating in-depth interviews, participant observations with informal discussions, and group discussions were conducted in Bu Gia Map commune, Binh Phuc province of Vietnam; in Phouvong district, Attapeu province of Laos; and, in nine newly established and informal communities in the provinces of Mondul Kiri, Steung Treng, Kratie, Kampong Thom, and Prah Vihear of Cambodia. RESULTS: Different types of factors limited or enhanced the effectiveness of the participatory approaches in the different settings. In Vietnam, inter-ethnic tensions and sensitivity around forest-work negatively affected local population's health-seeking behaviour and consequent uptake of malaria testing and treatment. In Laos, the location of the project collaborative pharmacies in the district-centre were a mismatch for reaching hard-to-reach populations in remote villages. In Cambodia, the strategy of recruiting community malaria-workers, elected by the community members, did manage to reach the remote forested areas where people visited or stayed. CONCLUSIONS: 'Hard-to-reach' populations remain hard to reach without proper research identifying the socio-economic-political environment and the key dynamics determining uptake in involved communities and populations. Solid implementation research with a strong ethnographic component is required to tailor malaria elimination strategies to local contexts.

Effect of Enzymatically Extracted Fucoidans on Angiogenesis and Osteogenesis in Primary Cell Culture Systems Mimicking Bone Tissue Environment.

Angiogenesis, the formation of new blood vessels from existing ones, is an essential process for successful bone regeneration. Further, angiogenesis is a key factor for the development of bone-related disorders like osteosarcoma or arthritis. Fucoidans, sulfated polysaccharides from brown algae, have been shown to affect angiogenesis as well as a series of other physiological processes including inflammation or infection. However, the chemical properties of fucoidan which define the biological activity vary tremendously, making a prediction of the bioactivity or the corresponding therapeutic effect difficult. In this study, we compare the effect of four chemically characterized high molecular weight fucoidan extracts from Fucus distichus subsp. evanescens (FE_crude and fractions F1, F2, F3) on angiogenic and osteogenic processes in bone-related primary mono- and co-culture cell systems. By determining the gene expression and protein levels of the regulatory molecules vascular endothelial growth factor (VEGF), angiopoietin-1 (ANG-1), ANG-2 and stromal-derived factor 1 (SDF-1), we show that the extracted fucoidans negatively influence angiogenic and osteogenic processes in both the mono- and co-culture systems. We demonstrate that purer fucoidan extracts with a high fucose and sulfate content show stronger effects on these processes. Immunocytochemistry of the co-culture system revealed that treatment with FE_F3, containing the highest fucose and sulfate content, impaired the formation of angiogenic tube-like structures, indicating the anti-angiogenic properties of the tested fucoidans. This study highlights how chemical properties of fucoidan influence its bioactivity in a bone-related context and discusses how the observed phenotypes can be explained on a molecular level-knowledge that is indispensable for future therapies based on fucoidans.

Enzyme-Assisted Fucoidan Extraction from Brown Macroalgae Fucus distichus subsp. evanescens and Saccharina latissima.

Fucoidans from brown macroalgae (brown seaweeds) have different structures and many interesting bioactivities. Fucoidans are classically extracted from brown seaweeds by hot acidic extraction. Here, we report a new targeted enzyme-assisted methodology for fucoidan extraction from brown seaweeds. This enzyme-assisted extraction protocol involves a one-step combined use of a commercial cellulase preparation (Cellic®CTec2) and an alginate lyase from Sphingomonas sp. (SALy), reaction at pH 6.0, 40 °C, removal of non-fucoidan polysaccharides by Ca2+ precipitation, and ethanol-precipitation of crude fucoidan. The workability of this method is demonstrated for fucoidan extraction from Fucus distichus subsp. evanescens (basionym Fucus evanescens) and Saccharina latissima as compared with mild acidic extraction. The crude fucoidans resulting directly from the enzyme-assisted method contained considerable amounts of low molecular weight alginate, but this residual alginate was effectively removed by an additional ion-exchange chromatographic step to yield pure fucoidans (as confirmed by 1H NMR). The fucoidan yields that were obtained by the enzymatic method were comparable to the chemically extracted yields for both F. evanescens and S. latissima, but the molecular sizes of the fucoidans were significantly larger with enzyme-assisted extraction. The molecular weight distribution of the fucoidan fractions was 400 to 800 kDa for F. evanescens and 300 to 800 kDa for S. latissima, whereas the molecular weights of the corresponding chemically extracted fucoidans from these seaweeds were 10-100 kDa and 50-100 kDa, respectively. Enzyme-assisted extraction represents a new gentle strategy for fucoidan extraction and it provides new opportunities for obtaining high yields of native fucoidan structures from brown macroalgae.

Use of antimicrobials and other medical products in an ethnic minority context of South-Central Vietnam: A qualitative study of vulnerability.

Despite the global threat of antimicrobial resistance (AMR), evidence on the use and quality of medicines at community level is limited, particularly in impoverished, rural areas where prevalence of (bacterial) infections is high. To better understand the processes that drive vulnerability to AMR' effects, this study aimed to assess social factors underpinning access to-and use of-medical products and healthcare, among people from the Raglai ethnic minority in Ninh Thuan Province, Vietnam. We conducted ethnographic research in eight villages in 2018-2019, using interviewing and participant observation methods for data collection. Different types of informants (including community members and healthcare providers) were selected using purposive sampling strategies and analysis was retroductive. Our findings show that, despite the existence of a government-funded health insurance scheme, Raglai people's flexible therapeutic itineraries did not systematically start with formal healthcare. Different types of care (private/informal, public, shamanic) were combined in parallel or in alternation, determined by distance to the provider, cost, workload, perceived diagnostic capacity, perceived severity and aetiology of the illness, and trust in the provider. Available medicines were often tablets dispensed in plastic bags containing labelled tablets, unlabelled tablets (in bulk) or tablets ground to powder. Treatment was often considered effective when it relieved symptoms, which led to abandonment of the treatment course. When symptoms did not speedily abate, the illness aetiology would be reinterpreted, and "stronger" medicines would be sought. The precarious socio-economic status of some Raglai drove them in cycles of severe poverty when additional unforeseen factors such as illness, animal disease or loss of crops arose, hampering access to (in)formal healthcare providers and/or appropriate diagnosis and treatment. We conclude that Raglai communities are structurally unable to buffer themselves against the threat and consequences of AMR. Despite this vulnerability, they are among the least targeted by efforts to optimize antibiotic use, which are concentrated in secondary and tertiary healthcare facilities targeted at urban populations.

Structural and functional characterization of the novel endo-α(1,4)-fucoidanase Mef1 from the marine bacterium Muricauda eckloniae.

Fucoidanases (EC 3.2.1.-) catalyze the hydrolysis of glycosidic bonds between fucose residues in fucoidans. Fucoidans are a compositionally and structurally diverse class of fucose-containing sulfated polysaccharides that are primarily found in brown seaweeds. Here, the structural characterization of a novel endo-α(1,4)-fucoidanase, Mef1, from the marine bacterium Muricauda eckloniae is presented, showing sequence similarity to members of glycoside hydrolase family 107. Using carbohydrate polyacrylamide gel electrophoresis and nuclear magnetic resonance analyses, it is shown that the fucoidanase Mef1 catalyzes the cleavage of α(1,4)-linkages between fucose residues sulfated on C2 in the structure [-3)-α-L-Fucp2S-(1,4)-α-L-Fucp2S-(1-]n in fucoidan from Fucus evanescens. Kinetic analysis of Mef1 activity by Fourier transform infrared spectroscopy revealed that the specific Mef1 fucoidanase activity (Uf) on F. evanescens fucoidan was 0.1 × 10-3 Uf µM-1. By crystal structure determination of Mef1 at 1.8 Šresolution, a single-domain organization comprising a (ß/α)8-barrel domain was determined. The active site was in an extended, positively charged groove that is likely to be designed to accommodate the binding of the negatively charged, sulfated fucoidan substrate. The active site of Mef1 comprises the amino acids His270 and Asp187, providing acid/base and nucleophile groups, respectively, for the hydrolysis of glycosidic bonds in the fucoidan backbone. Electron densities were identified for two possible Ca2+ ions in the enzyme, one of which is partially exposed to the active-site groove, while the other is very tightly coordinated. A water wire was discovered leading from the exterior of the Mef1 enzyme into the active site, passing the tightly coordinated Ca2+ site.

Depolymerization of fucoidan with endo-fucoidanase changes bioactivity in processes relevant for bone regeneration.

Fucoidans are polysaccharides from brown macroalgae, showing multiple bioactivities important for bone regeneration and bone health. However, the use of fucoidans in medical applications remains sparse due to the heterogeneity in their chemical properties and unclear structure-function relationships. Innovations in extraction techniques and post processing steps are needed to produce homogeneous fucoidan molecules with tailorable bioactivities. Here, we applied enzyme-assisted extraction coupled with enzymatic hydrolysis by Fhf1 fucoidanase to generate low (LMW) and medium molecular weight (MMW) fucoidans from Fucus evanescens. In contrast to the anti-angiogenic properties of the high molecular weight fucoidan, LMW and MMW no longer suppressed the production of pro-angiogenic molecules by bone stem cells, nor impaired the formation of prevascular structures in vitro. In contrast to LMW, a pro-inflammatory response of OEC was observed after treatment with high concentrations of MMW. Thus, fucoidanase hydrolysis could be a useful tool to tailor the bioactivity of fucoidans.

The Endo-α(1,4) Specific Fucoidanase Fhf2 From Formosa haliotis Releases Highly Sulfated Fucoidan Oligosaccharides.

Fucoidanases are endo-fucoidanases (also known as endo-fucanases) that catalyze hydrolysis of α-glycosidic linkages in fucoidans, a family of sulfated fucose-rich polysaccharides primarily found in the cell walls of brown seaweeds. Fucoidanases are promising tools for producing bioactive fucoidan oligosaccharides for a range of biomedical applications. High sulfation degree has been linked to high bioactivity of fucoidans. In this study, a novel fucoidanase, Fhf2, was identified in the genome of the aerobic, Gram-negative marine bacterium Formosa haliotis. Fhf2 was found to share sequence similarity to known endo-α(1,4)-fucoidanases (EC 3.2.1.212) from glycoside hydrolase family 107. A C-terminal deletion mutant Fhf2∆484, devoid of 484 amino acids at the C-terminus, with a molecular weight of approximately 46 kDa, was constructed and found to be more stable than the full-length Fhf2 protein. Fhf2∆484 showed endo-fucoidanase activity on fucoidans from different seaweed species including Fucus evanescens, Fucus vesiculosus, Sargassum mcclurei, and Sargassum polycystum. The highest activity was observed on fucoidan from F. evanescens. The Fhf2∆484 enzyme was active at 20-45°C and at pH 6-9 and had optimal activity at 37°C and pH 8. Additionally, Fhf2∆484 was found to be calcium-dependent. NMR analysis showed that Fhf2∆484 catalyzed hydrolysis of α(1,4) linkages between L-fucosyl moieties sulfated on C2 (similar to Fhf1 from Formosa haliotis), but Fhf2∆484 in addition released oligosaccharides containing a substantial amount of 2,4-disulfated fucose residues. The data thus suggest that the Fhf2∆484 enzyme could be a valuable candidate for producing highly sulfated oligosaccharides applicable for fucoidan bioactivity investigations.

Understanding Malaria Persistence: A Mixed-Methods Study on the Effectiveness of Malaria Elimination Strategies in South-Central Vietnam.

Despite the scale-up of vector control, diagnosis and treatment, and health information campaigns, malaria persists in the forested areas of South-Central Vietnam, home to ethnic minority populations. A mixed-methods study using an exploratory sequential design was conducted in 10 Ra-glai villages in Bac Ai district of Ninh Thuan province to examine which social factors limited the effectiveness of the national malaria elimination strategy in the local setting. Territorial arrangements and mobility were found to directly limit the effectiveness of indoor residual spraying and long-lasting insectidical treated nets (LLINs). Households (n=410) were resettled in the "new villages" by the government, where they received brick houses (87.1%) and sufficient LLINs (97.3%). However, 97.6% of households went back to their "old villages" to continue slash-and-burn agriculture. In the old village, 48.5% of households lived in open-structured plot huts and only 5.7% of them had sufficient LLIN coverage. Household representatives believed malaria could be cured with antimalarials (57.8%), but also perceived non-malarial medicines, rituals, and vitamin supplements to be effective against malaria. Household members (n = 1,957) used public health services for their most recent illness (62.9%), but also reported to buy low-cost medicines from the private sector to treat fevers and discomfort as these were perceived to be the most cost-effective treatment option for slash-and-burn farmers. The study shows the relevance of understanding social factors to improve the uptake of public health interventions and calls for contextually adapted strategies for malaria elimination in ethnic minority populations in Vietnam and similar settings.

A novel thermostable prokaryotic fucoidan active sulfatase PsFucS1 with an unusual quaternary hexameric structure.

Fucoidans are sulfated, fucose-rich marine polysaccharides primarily found in cell walls of brown seaweeds (macroalgae). Fucoidans are known to possess beneficial bioactivities depending on their structure and sulfation degree. Here, we report the first functional characterization and the first crystal structure of a prokaryotic sulfatase, PsFucS1, belonging to sulfatase subfamily S1_13, able to release sulfate from fucoidan oligosaccharides. PsFucS1 was identified in the genome of a Pseudoalteromonas sp. isolated from sea cucumber gut. PsFucS1 (57 kDa) is Ca2+ dependent and has an unusually high optimal temperature (68 °C) and thermostability. Further, the PsFucS1 displays a unique quaternary hexameric structure comprising a tight trimeric dimer complex. The structural data imply that this hexamer formation results from an uncommon interaction of each PsFucS1 monomer that is oriented perpendicular to the common dimer interface (~ 1500 Å2) that can be found in analogous sulfatases. The uncommon interaction involves interfacing (1246 Å2) through a bundle of α-helices in the N-terminal domain to form a trimeric ring structure. The high thermostability may be related to this unusual quaternary hexameric structure formation that is suggested to represent a novel protein thermostabilization mechanism.

Developing and validating five-construct model of customer satisfaction in beauty and cosmetic E-commerce.

Grounded on the American Customer Satisfaction Framework (ACSF) of Bryant (1995), the European Customer Satisfaction Framework Model (ECSF) of Anderson and Fornell (2000), and Eleven-factor Customer Satisfaction Model of Hokanson (1995), this study develops reliable and valid five constructs of customer satisfaction theoretical model and build up a questionnaire in the unique context of Beauty and Cosmetic Online Shopping in the Vietnamese market. More specifically, we identified five main constructs including 5 implementation constructs (i.e., online shopping experience, customer service, external incentives, security/privacy, and personal characteristics), and one outcome construct (i.e., customer satisfaction). A detailed questionnaire was then developed with items for these constructs along with the questions on the personal characteristics of the respondents. The questionnaire was sent to randomly consumers via online channels including Facebook. The target participants are Vietnamese people who have experience in shopping online products like beauty and cosmetics. Based on 334 full responses have been received, we use Exploratory Factor Analysis (EFA) to test for 167 observations to ensure that all items in each scale reflected sufficiently the scope of each construct. This technique helps to identify the underlying dimensions of consumer satisfaction. Furthermore, we also employ Confirmatory Factor Analysis (CFA) to validate the constructs and items in questionnaire. To do this, we have used the sample of 167 responses. Finally, together with results from SEM models, our study contributes to providing a reliable and valid questionnaire which fully reflect for our self-constructed theoretical model of five constructs including Online shopping experience (OSE), External incentives (EI), Seller service (SS), and Security/privacy (SP), as well as personal characteristics (PC).

Diagnostic Practices and Treatment for P. vivax in the InterEthnic Therapeutic Encounter of South-Central Vietnam: A Mixed-Methods Study.

Malaria elimination in the Greater Mekong Sub-Region is challenged by a rising proportion of malaria attributable to P. vivax. Primaquine (PQ) is effective in eliminating the parasite's dormant liver stages and can prevent relapsing infections, but it induces severe haemolysis in patients with Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency, highlighting the importance of testing enzyme activity prior to treatment. A mixed-method study was conducted in south-central Vietnam to explore the factors that affect acceptability of G6PD testing, treatment-seeking behaviors, and adherence to current regimens. The majority of respondents (75.7%) were unaware of the different parasite species and rather differentiated malaria by perceived severity. People sought a diagnosis if suspected of malaria fever but not if they perceived their fevers as mild. Most respondents agreed to take prescribed medication to treat asymptomatic infection (94.1%) and to continue medication even if they felt better (91.5%). Health professionals did not have G6PD diagnostic tools nor the means to prescribe PQ safely. Adherence to treatment was linked to trust in public providers, who were perceived to make therapeutic decisions in the interest of the patient. Greater focus on providing acceptable ways of assessing G6PD deficiency will be needed to ensure the timely elimination of malaria in Vietnam.