Association of green tea consumption with prediabetes, diabetes and markers of glucose metabolism in rural Vietnam: a cross-sectional study.

The literature on green tea consumption and glucose metabolism has reported conflicting findings. This cross-sectional study examined the association of green tea consumption with abnormal glucose metabolism among 3000 rural residents aged 40-60 years in Khánh Hòa province in Vietnam. Multinomial logistic regression analysis was conducted to examine the association of green tea consumption (0, < 200, 200-< 400, 400-< 600 or ≥ 600 ml/d) with prediabetes and diabetes (based on the American Diabetes Association criteria). Linear regression analysis was performed to examine the association between green tea consumption and the log-transformed homeostatic model assessment of insulin resistance (HOMA-IR) (a marker of insulin resistance) and the log-transformed homeostatic model assessment of ß-cell function (HOMA-ß) (a marker of insulin secretion). The OR for prediabetes and diabetes among participants who consumed ≥ 600 ml/d v. those who did not consume green tea were 1·61 (95 % CI = 1·07, 2·42) and 2·04 (95 % CI = 1·07, 3·89), respectively. Higher green tea consumption was associated with a higher level of log-transformed HOMA-IR (Pfor trend = 0·04) but not with a lower level of log-transformed HOMA-ß (Pfor trend = 0·75). Higher green tea consumption was positively associated with the prevalence of prediabetes, diabetes and insulin resistance in rural Vietnam. The findings of this study indicated prompting the need for further research considering context in understanding the link between green tea consumption and glucose metabolism, especially in rural settings in low- and middle-income countries.

Sex differences in the association between socioeconomic status and untreated hypertension among residents with hypertension in rural Khánh Hòa, Vietnam: a post-hoc analysis.

BACKGROUND: Several studies have examined the association between socioeconomic status (SES) and the proportion of untreated hypertension, but have produced conflicting findings. In addition, no study has been conducted to determine sex differences in the association between SES and untreated hypertension. Thus, the aim of this study was to examine whether the associations between SES and the proportion of untreated hypertension differed by sex in Vietnam. METHODS: This study was conducted using the data of 1189 individuals (558 males and 631 females) who were judged to have hypertension during the baseline survey of a prospective cohort study of 3000 residents aged 40-60 years in the Khánh Hòa Province. A multilevel Poisson regression model with a robust variance estimator was used to examine whether sex and SES indicators (household income and educational attainment) interacted in relation to untreated hypertension. RESULTS: The proportion of untreated hypertension among individuals identified as hypertensive was 69.1%. We found significant interaction between sex and SES indicators in relation to untreated hypertension (education: p < 0.001; household income: p < 0.001). Specifically, the association between SES and untreated hypertension was inverse among males while it was rather positive among females. CONCLUSIONS: Our finding suggests that the role of SES in the proportion of untreated hypertension might differ by sex.

Parental absence during childhood and weight status in adulthood among middle-aged community dwellers in rural Vietnam.

OBJECTIVES: While adverse childhood experiences (ACEs) have been shown to be associated with adulthood obesity, less is known about their association with underweight. We examined the associations between parental absence (i.e., a major component of ACEs) and both underweight and excess weight among middle-aged rural community dwellers in Vietnam, where experiences of parental absence was not uncommon during and after the Vietnam War (1955-1975). METHODS: Data came from 3000 middle-aged adults who participated in the baseline survey of Khánh Hòa Cardiovascular Study. Parental absence was defined as parental absence due to death, divorce, or out-migration. Using information on the timing of such events, we categorized participants into those who experienced parental absence before the age of 3, between the ages of 3 and 15, and those without such experiences. BMI was calculated based on measured height and weight (kg/m2 ) and categorized into three groups: underweight <18.5; normal 18.5-24.9; excess weight ≥ 25. Multinomial logistic regression was then used to investigate the association between parental absence and adult weight status. RESULTS: Parental absence that occurred before the age of 3 was marginally significantly associated with underweight (relative risk ratio [RRR] = 1.44, 95% confidence interval [CI] 0.95, 2.20) but not with overweight/obesity. Parental divorce was associated with overweight/obesity (RRR = 2.48, 95% CI 1.28, 4.81), but not parental absence due to migratory work. CONCLUSIONS: While previous studies in Western settings focused almost exclusively on the risk of obesity in relation to exposure to ACEs, our findings point to the potential importance of considering the risk of underweight in low- and middle-income countries.

Red meat consumption is associated with prediabetes and diabetes in rural Vietnam: a cross-sectional study.

OBJECTIVE: To examine the association between red/processed meat consumption and glycaemic conditions (i.e. prediabetes (preDM) and diabetes mellitus (DM)) among middle-aged residents in rural Khánh Hòa, Vietnam. DESIGN: In this cross-sectional study, a multinomial logistic regression model was used to examine the association between daily consumption of red/processed meat (0-99 g, 100-199 g or ≥ 200 g) and preDM/DM with adjustments for socio-demographic, lifestyle-related and health-related variables. SETTING: Khánh Hòa Province, Vietnam. PARTICIPANTS: The study used data collected through a baseline survey conducted during a prospective cohort study on CVD among 3000 residents, aged 40-60 years, living in rural communes in Khánh Hòa Province. RESULTS: The multinomial regression model revealed that the relative-risk ratios for DM were 1·00 (reference), 1·11 (95 % CI = 0·75, 1·62) and 1·80 (95 % CI = 1·40, 2·32) from the lowest to the highest red/processed meat consumption categories (Ptrend = 0·006). The corresponding values for preDM were 1·00 (reference), 1·25 (95 % CI = 1·01, 1·54) and 1·67 (95 % CI = 1·20, 2·33) (Ptrend = 0·004). We did not find any evidence of statistical significance in relation to poultry consumption. CONCLUSION: Increased red/processed meat consumption, but not poultry consumption, was positively associated with the prevalence of preDM/DM in rural communes in Khánh Hòa Province, Vietnam. Dietary recommendations involving a reduction in red/processed meat consumption should be considered in low- and middle-income countries.

Association between parental absence during childhood and metabolic syndrome during adulthood: A cross-sectional study in rural Khanh Hoa, Vietnam.

BACKGROUND: This study aimed to determine the association between parental absence during childhood and metabolic syndrome (MetS) in adulthood among middle-aged adults in rural Khanh Hoa province, Vietnam. Given that broader literature on adverse childhood experiences (ACEs) suggests a strong positive association between ACEs and cardiometabolic risk or diseases, we hypothesized that parental absence during childhood, which is a major component of ACEs, is more likely to cause MetS in adulthood. METHODS: Data were obtained from the baseline survey of the Khanh Hoa Cardiovascular Study, in which 3000 residents aged between 40 to 60 years participated. MetS was assessed using the modified Adult Treatment Panel III (ATP III) criteria. It was considered parental absence if the participants had experienced parental absence due to death, divorce, or out-migration before three or between three to 15 years. We used multiple logistic regression analyses to examine the association between parental absence during childhood and metabolic syndrome during adulthood. RESULTS: There was no significant association between parental absence and MetS; adjusted odds ratio [AOR] was 0.97 (95% confidence interval [CI] = 0.76-1.22) for those who experienced parental absence between three to 15 years and the corresponding figure for those who experienced it before three years was 0.93 (95% CI = 0.72-1.20). No significant associations were observed when these were examined for the causes of parental absence. CONCLUSION: This study did not support our hypothesis of an association between parental absence during childhood and metabolic syndrome during adulthood. Parental absence may not be a predictor of MetS among Vietnamese people in rural communities.

Endocytosis of red blood cell extracellular vesicles by macrophages leads to cytoplasmic heme release and prevents foam cell formation in atherosclerosis.

Extracellular vesicles (EVs) can be produced from red blood cells (RBCs) on a large scale and used to deliver therapeutic payloads efficiently. However, not much is known about the native biological properties of RBCEVs. Here, we demonstrate that RBCEVs are primarily taken up by macrophages and monocytes. This uptake is an active process, mediated mainly by endocytosis. Incubation of CD14+ monocytes with RBCEVs induces their differentiation into macrophages with an Mheme-like phenotype, characterized by upregulation of heme oxygenase-1 (HO-1) and the ATP-binding cassette transporter ABCG1. Moreover, macrophages that take up RBCEVs exhibit a reduction in surface CD86 and decreased secretion of TNF-α under inflammatory stimulation. The upregulation of HO-1 is attributed to heme derived from haemoglobin in RBCEVs. Heme is released from internalized RBCEVs in late endosomes and lysosomes via the heme transporter, HRG1. Consequently, RBCEVs exhibit the ability to attenuate foam cell formation from oxidized low-density lipoproteins (oxLDL)-treated macrophages in vitro and reduce atherosclerotic lesions in ApoE knockout mice on a high-fat diet. In summary, our study reveals the uptake mechanism of RBCEVs and their delivery of heme to macrophages, suggesting the potential application of RBCEVs in the treatment of atherosclerosis.

Red Blood Cell-Derived Extracellular Vesicles Display Endogenous Antiviral Effects and Enhance the Efficacy of Antiviral Oligonucleotide Therapy.

The COVID-19 pandemic has resulted in a large number of fatalities and, at present, lacks a readily available curative treatment for patients. Here, we demonstrate that unmodified red blood cell-derived extracellular vesicles (RBCEVs) can inhibit SARS-CoV-2 infection in a phosphatidylserine (PS) dependent manner. Using T cell immunoglobulin mucin domain-1 (TIM-1) as an example, we demonstrate that PS receptors on cells can significantly increase the adsorption and infection of authentic and pseudotyped SARS-CoV-2 viruses. RBCEVs competitively inhibit this interaction and block TIM-1-mediated viral entry into cells. We further extend the therapeutic efficacy of this antiviral treatment by loading antisense oligonucleotides (ASOs) designed to target conserved regions of key SARS-CoV-2 genes into RBCEVs. We establish that ASO-loaded RBCEVs are efficiently taken up by cells in vitro and in vivo to suppress SARS-CoV-2 replication. Our findings indicate that this RBCEV-based SARS-CoV-2 therapeutic displays promise as a potential treatment capable of inhibiting SARS-CoV-2 entry and replication.

Case Report: Exposure to Respirable Crystalline Silica and Respiratory Health Among Australian Mine Workers.

Occupational exposure to respirable crystalline silica (RCS) is common in a range of industries, including mining, and has been associated with adverse health effects such as silicosis, lung cancer, and non-malignant respiratory diseases. This study used a large population database of 6,563 mine workers from Western Australia who were examined for personal exposure to RCS between 2001 and 2012. A standardized respiratory questionnaire was also administered to collect information related to their respiratory health. Logistic regression analyses were performed to ascertain the association between RCS concentrations and the prevalence of respiratory symptoms among mine workers. The estimated exposure levels of RCS (geometric mean 0.008mg/m3, GSD 4.151) declined over the study period (p < 0.001) and were below the exposure standard of 0.05 mg/m3. Miners exposed to RCS had a significantly higher prevalence of phlegm (p = 0.017) and any respiratory symptom (p = 0.013), even at concentrations within the exposure limit. Miners are susceptible to adverse respiratory health effects at low levels of RCS exposure. More stringent prevention strategies are therefore recommended to protect mine workers from RCS exposures.

Infection prevention practices and its associated factors among hospital workers in a national medical center designated for COVID-19 in Tokyo, Japan.

BACKGROUND: While healthcare workers (HCWs) are at risk of occupational exposure to SARS-CoV-2 infection, the virus transmission involving them might be exceeding in the non-occupational settings. This study examined the extent of adherence to infection prevention practices (IPPs) against COVID-19 in their daily life and its associated factors among staff members in a national medical center designated for COVID-19 treatment in Tokyo, Japan. METHODS: This cross-sectional study was conducted in July 2020 among 1,228 staff of National Center for Global Health and Medicine (NCGM). We asked participants about their adherence on six IPPs recommended by the WHO in their daily lives, which included wearing masks, maintaining hand and respiratory hygiene, avoiding 3Cs and social distancing. We defined 100% adherence (6 points) to IPPs as good adherence and run logistic regression model to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of IPPs. RESULTS: Nearly 100% of NCGM staff members adhered to four out of six IPPs assessed in this study: washing or sanitizing hands (99.6%), good cough etiquette (99.6%), wearing mask (98.9%), and avoiding 3Cs (98.3%). Doctors (AOR = 2.18, CI: 1.36-3.49) and female staff members (AOR = 1.95, CI: 1.36-3.49) were more likely to adhere to IPPs compared with non-clinical staffs and male counterparts. Good adherence to IPPs tended to increase with older age, with highest adherence among those who were 50 years or above (AOR = 2.53, CI: 1.49-4.29). CONCLUSION: This study revealed that the IPPs among NCGM staff was remarkably good. Older and female staff members, and doctors showed a higher adhere to IPPs compared with their counterparts. Additional effort to improve adherence to IPPs among the younger and male staff members could contribute to reduce infection risk in their daily life, which can eventually prevent nosocomial infection.

Association between chronic physical conditions and depressive symptoms among hospital workers in a national medical institution designated for COVID-19 in Japan.

OBJECTIVE: This study aimed to investigate the cross-sectional association between the presence of chronic physical conditions and depressive symptoms among hospital workers at a national medical institution designated for COVID-19 treatment in Tokyo, Japan. We also accounted for the combined association of chronic physical conditions and SARS-CoV-2 infection risk at work in relation to depressive symptoms, given that occupational infection risk might put additional psychological burden among those with chronic physical conditions with risk of severe COVID-19 outcome. METHODS: The study sample consisted of 2,440 staff members who participated in a health survey conducted at the national medical institution during period between October 2020 and December 2020. Participants who reported at least one chronic physical condition that were deemed risk factors of severe COVID-19 outcome were regarded as having chronic physical conditions. Depressive symptoms were assessed using the patient health questionnaire-9 (PHQ-9). We performed logistic regression analysis to assess the association between chronic physical conditions and depressive symptoms. RESULTS: Our results showed that the presence of chronic physical conditions was significantly associated with depressive symptoms (odds ratio (OR) = 1.49, 95% confidence interval (CI) = 1.10-2.02). In addition, the prevalence of depressive symptoms was significantly higher among healthcare workers with chronic physical conditions who were at a higher occupational infection risk (OR = 1.81, 95% CI = 1.04-3.16). CONCLUSION: Our findings suggest the importance of providing more assistance to those with chronic physical conditions regarding the prevention and control of mental health issues, particularly among frontline healthcare workers engaging in COVID-19-related work.

Association between parental absence during childhood and depressive symptoms in adulthood in rural Vietnam.

BACKGROUND: While parental absence during childhood has been linked to depression/depressive symptoms in adulthood, no research has been conducted on this association in Vietnam, where many children were separated from their parents during and after the Vietnam War (1955-1975). We examined the association between parental absence in childhood and depressive symptoms among rural community dwellers in Khanh Hoa Province, Vietnam. METHODS: Data came from 3000 individuals aged 40-60 years old who participated in the baseline survey of the Khanh Hoa Cardiovascular Study. Depressive symptoms were assessed with the 11-item Center for Epidemiologic Studies Depression Scale. Self-reported information on parental absence due to death, divorce, or outmigration to other locations before the age of 15 was also obtained. A Poisson regression analysis with a robust variance estimator was used to examine associations. RESULTS: Experiencing parental absence at 3 - < 15 years old and before 3 years old was associated with a 1.21 times (95% confidence interval [CI] = 1.02-1.43) and 1.41 times (95% CI = 1.15-1.73) higher prevalence of depressive symptoms, respectively (p trend <0.001). When examining the associations by the different reasons for the parental absence, the strongest association was found for parental absence due to outmigration to other locations. LIMITATIONS: We had no information on who respondents lived with after they experienced parental absence. In addition, self-reported information on childhood experiences was subject to recall bias. CONCLUSIONS: In rural Vietnam, parental absence during childhood was associated with a significantly increased prevalence of depressive symptoms in middle adulthood.

Individual-level social capital is associated with depressive symptoms among middle-aged community dwellers in rural Vietnam: a cross-sectional study.

OBJECTIVES: There has been comparatively little research on the association between social capital and depressive symptoms in low- and middle-income countries. To address this deficit this study examined the association among middle-aged adults in rural Vietnam. DESIGN: A cross-sectional study. SETTING: Data came from the baseline survey of the Khánh Hòa Cardiovascular Study, which is an ongoing prospective cohort study aiming to elucidate the determinants of cardiovascular diseases. PARTICIPANTS: A total of 3000 people aged 40-60 years old residing in rural communes in Khánh Hòa province, Vietnam. EXPOSURE OF INTEREST: Cognitive social capital (ie, low, middle and high) and structural social capital (in terms of social participation; yes or no) were assessed via a questionnaire. PRIMARY OUTCOME MEASURE: Depressive symptoms were assessed with the 11-item Center for Epidemiologic Studies Depression Scale. RESULTS: A robust Poisson regression model revealed that adults in the highest versus lowest cognitive social capital tertile had a 61% lower prevalence of depressive symptoms (prevalence ratio (PR)=0.39, 95% CI=0.31 to 0.49). Individuals with higher structural social capital were also significantly less likely to experience depressive symptoms (PR=0.74, 95% CI=0.61 to 0.90). CONCLUSION: In a cohort of 3000 middle-aged rural residents in Vietnam, both cognitive and structural social capital assessed at the individual level were inversely associated with the prevalence of depressive symptoms.

Is there an association between ABO blood types and depressive symptoms among Japanese healthcare workers during the COVID-19 pandemic?

ABO blood types could be a biological predisposition for depression. The present cross-sectional analysis was conducted amid the second wave of COVID-19 in Japan during July 2020. We wanted to investigate the association between ABO blood types and depressive symptoms among workers (352 men and 864 women, aged 21-73 years) of a medical institution in Tokyo, Japan, which took a leading role in the response to COVID-19 in the country. A Poisson regression model with a robust variance estimator was used to estimate the prevalence ratio (PR) and 95% confidence interval (CI) for depressive symptoms associated with ABO blood types. Overall, the prevalence of depressive symptoms (using two questions employed from a Two-question case-finding instrument) was 22.0%. The adjusted PRs (95% CI) for depressive symptoms, comparing the carriers of blood type O, A, and AB with those of type B, were 0.88 (0.66, 1.18), 0.81 (0.62, 1.07), and 1.07 (0.74, 1.53), respectively. There was no difference in the prevalence of depressive symptoms between non-B and B carriers. The present study did not support the association of ABO blood types with depressive symptoms.

Association between engagement in COVID-19-related work and depressive symptoms among hospital workers in a designated COVID-19 hospital in Japan: a cross-sectional study.

OBJECTIVES: To examine whether engagement in COVID-19-related work was associated with an increased prevalence of depressive symptoms among the staff members working in a designated medical institution for COVID-19 in Tokyo, Japan. DESIGN: A cross-sectional study. SETTING: Data were obtained from a health survey conducted in July 2020 among the staff members of a designated medical institution for COVID-19 in Tokyo, Japan. PARTICIPANTS: A total of 1228 hospital workers. EXPOSURE OF INTEREST: Engagement in COVID-19-related work (qualitatively (ie, the risk of SARS-CoV-2 infection at work or affiliation to related departments) as well as quantitatively (ie, working hours)) and job categories. OUTCOME MEASURES: Depressive symptoms. RESULTS: There was no significant association between depressive symptoms and engagement in work with potential exposure to SARS-CoV-2 or affiliation to COVID-19-related departments. However, working for longer hours in March/April, when Japan witnessed a large number of infected cases, was significantly associated with depressive symptoms (≥11 hours/day: prevalence ratio (PR)=1.45, 95% CI=1.06 to 1.99, compared with ≤8 hours/day). Nurses were more likely to exhibit depressive symptoms than did doctors (PR=1.70, 95% CI=1.14 to 2.54). CONCLUSIONS: This study suggests that the risk of SARS-CoV-2 infection at work or having an affiliation to related departments might not be linked with a higher prevalence of depressive symptoms among Japanese hospital workers; contrarily, long working hours appeared to increase the prevalence of depressive symptoms.

Trends in Exposure to Diesel Particulate Matter and Prevalence of Respiratory Symptoms in Western Australian Miners.

Diesel-powered equipment is used frequently in the mining industry. They are energetically more efficient and emit lower quantities of carbon monoxide and carbon dioxide than the gasoline equipment. However, diesel engines release more diesel particulate matter (DPM) during the combustion process which has been linked to harmful health effects. This study assessed the trends in DPM exposure and the prevalence of respiratory symptoms among Western Australian miners, using the available secondary data collected from 2006 to 2012. The data consisted of elemental carbon (EC) concentrations and information on miner's respiratory symptoms. The measured EC concentrations from n = 2598 miners ranged between 0.01 mg/m3 and 1.00 mg/m3 and tended to significantly decrease over the study period (p < 0.001). Underground mine workers were exposed to significantly higher (p < 0.01) median EC concentrations of 0.069 mg/m3 (IQR 0.076) when compared to surface workers' 0.038 mg/m3 (IQR 0.04). Overall, 29% of the miners reported at least one respiratory symptom, with the highest frequency recorded for cough (16%). Although the exposure levels of DPM in the mining industry of Western Australia have declined over the study period, they are still high and adhering to stringent occupational standard for DPM is recommended.

Dietary inflammatory index is associated with increased risk for prostate cancer among Vietnamese men.

OBJECTIVE: Inflammatory potential of diet, as measured by the dietary inflammatory index (DII), has consistently been associated with an increased risk for prostate cancer (PCa). However, data has largely been reported in populations with more proinflammatory dietary patterns, whereas there is high diversity in dietary pattern worldwide. The aim of this study was to assess the association between DII scores and the risk for PCa in Vietnam. METHODS: A case-control study of 652 participants (244 incident PCa patients, 64-75 y of age, and 408 controls, frequency matched for age) was conducted in Ho Chi Minh City, Vietnam, from 2013 to 2015. Habitual diet was ascertained using a validated food frequency questionnaire (FFQ), whereas other factors, including demographic and lifestyle characteristics, were assessed via face-to-face interviews. The daily intake of pro- and anti-inflammatory nutrients for each participant was calculated from the FFQ and used to estimate individuals' energy-adjusted DII (E-DII) scores. Multivariate-adjusted odds ratios (OR) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression models. RESULTS: Comparing the middle and highest versus lowest tertile of DII scores, there was an increased risk for overall PCa. The OR and associated 95% CI was 2.63 (1.61-4.37) and 3.35 (2.06-5.53), respectively (Ptrend < 0.01). Similar results were found for low-moderate and high-grade PCa. The respective ORs (95% CI) were 3.34 (1.66-7.13) and 5.29 (2.69-11.18), Ptrend < 0.001, and 2.51 (1.40-4.63) and 2.57 (1.43-4.73), Ptrend 0.006. CONCLUSION: A proinflammatory diet was associated with increased risk for PCa among Vietnamese men.

Low Dietary Intakes of Essential Nutrients during Pregnancy in Vietnam.

Inadequate intake of nutrients during pregnancy has been associated with poor pregnancy and infant outcomes; however, evidence remains limited in low-resource settings in Asia. This paper assessed food, macronutrient, and micronutrient intakes among 1944 Vietnamese pregnant women. Dietary information was collected via an interviewer-administered food frequency questionnaire, and nutrient intakes were estimated using the Vietnamese food composition tables. The levels of nutrient intakes were evaluated against the Vietnamese recommended nutrient intakes (RNI) for pregnancy. The diet profiles were reported as means and percentages. The average daily food intakes across socio-demographic factors were compared using ANOVA, with adjustment for multiple comparisons by the Tukey⁻Kramer test. Rice, fruits, and vegetables were the main food sources consumed. The mean energy intake was 2004 kcal/day with 15.9%, 31.8%, and 52.2% of energy deriving from proteins, fats, and carbohydrates, respectively. Just over half of the women did not meet the RNI for total energy intake. The intakes of essential micronutrients including folate, calcium, iron, and zinc were below the RNI, and almost all pregnant women failed to meet the recommendations for these micronutrients. The associations of maternal age, education, and pre-pregnancy body mass index with nutrient intakes varied across the nutrient subgroups. Targeted programs are needed to improve nutrient intakes in Vietnamese pregnant women.

Epidemiological, Serological, and Virological Features of Dengue in Nha Trang City, Vietnam.

Vietnam is endemic for dengue. We conducted a series of retrospective and prospective studies to characterize the epidemiology of dengue and population mobility patterns in Nha Trang city, Vietnam, with a view to rational design of trials of community-level interventions. A 10-year time series of dengue case notifications showed pronounced interannual variability, as well as spatial heterogeneity in ward-level dengue incidence (median annual coefficient of variation k = 0.47). Of 451 children aged 1-10 years enrolled in a cross-sectional serosurvey, almost one-third had evidence of a past dengue virus (DENV) infection, with older children more likely to have a multitypic response indicative of past exposure to ≥ 1 serotype. All four DENV serotypes were detected in hospitalized patients during 8 months of sampling in 2015. Mobility data collected from 1,000 children and young adults via prospective travel diaries showed that, although all ages spent approximately half of their daytime hours (5:00 am-9:00 pm) at home, younger age groups (≤ 14 years) spent a significantly greater proportion of their time within 500 m of home than older respondents. Together these findings inform the rational design of future trials of dengue preventive interventions in this setting by identifying 1) children < 7 years as an optimal target group for a flavivirus-naive serological cohort, 2) children and young adults as the predominant patient population for a study with a clinical end point of symptomatic dengue, and 3) substantial spatial and temporal variations in DENV transmission, with a consequent requirement for a trial to be large enough and of long enough duration to overcome this heterogeneity.