Under-5 mortality surveillance in low-income and middle-income countries: insights from two Health and Demographic Surveillance Systems in rural Gambia

Without complete data on under-5 mortality, tracking progress towards achieving Sustainable Development Goal 3.2 will be challenging. Such data are also needed to ensure proper planning and prioritisation of scarce resources in low-income and middle-income countries. However, most low-income and middle-income countries have weak Civil Registration and Vital Statistics (CRVS) systems, leaving a critical gap in understanding under-5 mortality dynamics. This paper outlines a community-based approach to enhance under-5 mortality surveillance in low-income countries, using The Gambia as a case study. The methodology involves Health and Demographic Surveillance Systems (HDSSs) in Basse and Fuladu West, employing unique identification numbers, periodical household visits and collaboration with communities, village reporters and project field workers to ensure comprehensive data collection. Verbal autopsies (VAs) are conducted by trained field workers, and causes of death are determined using the physician-certified VA method. Between 1 September 2019 and 1 September 2023, 1333 deaths were detected, for which causes of death were determined for 97.1% (1294 of 1333). The most common causes of death detected were acute respiratory infections including pneumonia, sepsis, diarrhoeal diseases and birth asphyxia. Challenges include the cost of maintaining the HDSSs, poor road infrastructure, Electronic Data Capture transition challenges, and the need for national integration of HDSS data into the CRVS system. The success of this model highlights its potential for scalable and adaptable under-5 mortality surveillance in resource-limited settings.

Impact of particulate nitrate photolysis on air quality over the Northern Hemisphere

We use the Community Multiscale Air Quality (CMAQv5.4) model to examine the potential impact of particulate nitrate (pNO3-) photolysis on air quality over the Northern Hemisphere. We estimate the photolysis frequency of pNO3- by scaling the photolysis frequency of nitric acid (HNO3) with an enhancement factor that varies between 10 and 100 depending on pNO3- and sea-salt aerosol concentrations and then perform CMAQ simulations without and with pNO3- photolysis to quantify the range of impacts on tropospheric composition. The photolysis of pNO3- produces gaseous nitrous acid (HONO) and nitrogen dioxide (NO2) over seawater thereby increasing atmospheric HONO and NO2 mixing ratios. HONO subsequently undergoes photolysis, producing hydroxyl radicals (OH). The increase in NO2 and OH alters atmospheric chemistry and enhances the atmospheric ozone (O3) mixing ratio over seawater, which is subsequently transported to downwind continental regions. Seasonal mean model O3 vertical column densities without pNO3- photolysis are lower than the Ozone Monitoring Instrument (OMI) retrievals, while the column densities with the pNO3- photolysis agree better with the OMI retrievals of tropospheric O3 burden. We compare model O3 mixing ratios with available surface observed data from the U.S., Japan, the Tropospheric Ozone Assessment Report - Phase II, and OpenAQ; and find that the model without pNO3- photolysis underestimates the observed data in winter and spring seasons and the model with pNO3- photolysis improves the comparison in both seasons, largely rectifying the pronounced underestimation in spring. Compared to measurements from the western U.S., model O3 mixing ratios with pNO3- photolysis agree better with observed data in all months due to the persistent underestimation of O3 without pNO3- photolysis. Compared to the ozonesonde measurements, model O3 mixing ratios with pNO3- photolysis also agree better with observed data than the model O3 without pNO3- photolysis.

Population Enumeration and Household Utilization Survey Methods in the Enterics for Global Health (EFGH): Shigella Surveillance Study

Background

Accurate estimation of diarrhea incidence from facility-based surveillance requires estimating the population at risk and accounting for case patients who do not seek care. The Enterics for Global Health (EFGH) Shigella surveillance study will characterize population denominators and healthcare-seeking behavior proportions to calculate incidence rates of Shigella diarrhea in children aged 6-35 months across 7 sites in Africa, Asia, and Latin America.

Methods

The Enterics for Global Health (EFGH) Shigella surveillance study will use a hybrid surveillance design, supplementing facility-based surveillance with population-based surveys to estimate population size and the proportion of children with diarrhea brought for care at EFGH health facilities. Continuous data collection over a 24 month period captures seasonality and ensures representative sampling of the population at risk during the period of facility-based enrollments. Study catchment areas are broken into randomized clusters, each sized to be feasibly enumerated by individual field teams.

Conclusions

The methods presented herein aim to minimize the challenges associated with hybrid surveillance, such as poor parity between survey area coverage and facility coverage, population fluctuations, seasonal variability, and adjustments to care-seeking behavior.

Data Management in Multicountry Consortium Studies: The Enterics For Global Health (EFGH) Shigella Surveillance Study Example

Background

Rigorous data management systems and planning are essential to successful research projects, especially for large, multicountry consortium studies involving partnerships across multiple institutions. Here we describe the development and implementation of data management systems and procedures for the Enterics For Global Health (EFGH) Shigella surveillance study-a 7-country diarrhea surveillance study that will conduct facility-based surveillance concurrent with population-based enumeration and a health care utilization survey to estimate the incidence of Shigella--associated diarrhea in children 6 to 35 months old.

Methods

The goals of EFGH data management are to utilize the knowledge and experience of consortium members to collect high-quality data and ensure equity in access and decision-making. During the planning phase before study initiation, a working group of representatives from each EFGH country site, the coordination team, and other partners met regularly to develop the data management systems for the study.

Results

This resulted in the Data Management Plan, which included selecting REDCap and SurveyCTO as the primary database systems. Consequently, we laid out procedures for data processing and storage, study monitoring and reporting, data quality control and assurance activities, and data access. The data management system and associated real-time visualizations allow for rapid data cleaning activities and progress monitoring and will enable quicker time to analysis.

Conclusions

Experiences from this study will contribute toward enriching the sparse landscape of data management methods publications and serve as a case study for future studies seeking to collect and manage data consistently and rigorously while maintaining equitable access to and control of data.

The Enterics for Global Health (EFGH) Shigella Surveillance Study in The Gambia

Background

The Gambia, located in West Africa, is one of 7 country sites conducting the Enterics for Global Health (EFGH) Shigella Surveillance Study to establish incidence and consequence of Shigella-associated medically attended diarrhea among children 6-35 months old.

Methods

Here we describe the study site and research experience, sociodemographic characteristics of the study catchment area, facilities of recruitment for diarrhea case surveillance, and known care-seeking behavior for diarrheal illness. We also describe The Gambia's healthcare system and financing, current vaccine schedule and Shigella vaccine adaptation, local diarrhea management guidelines and challenges, and antibiotic resistance patterns in the region.

Conclusions

The EFGH study in The Gambia will contribute to the multisite network of Shigella surveillance study and prepare the site for future vaccine trials. In addition, the data produced will inform policy makers about prevention strategies and upcoming Shigella vaccine studies among children in this setting.

Personal exposure to household air pollution and lung function in rural Bangladesh: A population-based cross-sectional study

We assessed whether personal exposure to household air pollution [PM2.5 and black carbon (BC)] is associated with lung functions (FEV1, FVC, and their ratio) in non-smoking adults in rural Bangladesh. We measured personal exposure to PM2.5 using gravimetric analysis of PM2.5 mass and BC by reflectance measurement between April 2016 and June 2019. The average 24-hour PM2.5 and BC concentration was 141.0μgm-3 and 13.8μgm-3 for females, and 91.7 μgm-3 and 10.1 μgm-3 for males, respectively. A 1 μgm-3 increase in PM2.5 resulted in a 0.02 ml reduction in FEV1, 0.43 ml reduction in FVC, and 0.004% reduction in FEV1/FVC. We also found a similar inverse relationship between BC and lung functions (9.6 ml decrease in FEV1 and 18.5 ml decrease in FVC per 1μgm-3 increase in BC). A higher proportion of non-smoking biomass fuel users (50.1% of the females and 46.7% of the males) had restrictive patterns of lung function abnormalities, which need further exploration.

Impact of the COVID-19 pandemic on the coverage and timeliness of routine childhood vaccinations in the Gambia, 2015-2021

INTRODUCTION

The COVID-19 pandemic caused widespread morbidity and mortality and resulted in the biggest setback in routine vaccinations in three decades. Data on the impact of the pandemic on immunisation in Africa are limited, in part, due to low-quality routine or administrative data. This study examined coverage and timeliness of routine childhood immunisation during the pandemic in The Gambia, a country with an immunisation system considered robust.

METHODS

We obtained prospective birth cohort data of 57 286 children in over 300 communities in two health and demographic surveillance system sites, including data from the pre-pandemic period (January 2015-February 2020) and the three waves of the pandemic period (March 2020-December 2021). We determined monthly coverage and timeliness (early and delayed) of the birth dose of hepatitis B vaccine (HepB0) and the first dose of pentavalent vaccine (Penta1) during the different waves of the pandemic relative to the pre-pandemic period. We implemented a binomial interrupted time-series regression model.

RESULT

We observed no significant change in the coverage of HepB0 and Penta1 vaccinations from the pre-pandemic period up until the periods before the peaks of the first and second waves of the pandemic in 2020. However, there was an increase in HepB0 coverage before as well as after the peak of the third wave in 2021 compared with the pre-pandemic period (pre-third wave peak OR = 1.83, 95% CI 1.06 to 3.14; post-third wave period OR=2.20, 95% CI 1.23 to 3.92). There was some evidence that vaccination timeliness changed during specific periods of the pandemic. Early Penta1 vaccination decreased by 70% (OR=0.30, 95% CI 0.12 to 0.78) in the period before the second wave, and delayed HepB0 vaccination decreased by 47% (OR=0.53, 95% CI 0.29 to 0.97) after the peak of the third wave in 2021.

CONCLUSION

Despite the challenges of the COVID-19 pandemic, The Gambia's routine vaccination programme has defied the setbacks witnessed in other settings and remained resilient, with coverage increasing and timeliness improving during the second and third waves. These findings highlight the importance of having adequate surveillance systems to monitor the impact of large shocks to vaccination coverage and timeliness.

Efficacy of urban road salt reduction strategies on public supply well quality

Long-term road salt application has increased chloride (Cl-) concentrations in public drinking water wells in many cold climate communities. A range of Best Management Practices (BMPs) have been adopted to mitigate the impact of road deicing compounds on groundwater quality. Chronic increases in chloride levels have been observed in several municipal well fields within the southern Ontario Regional Municipality of Waterloo (RMOW). In response, the RMOW and City of Kitchener implemented a plan to reduce salt application on roads by 25% within the local capture zones of one of the impacted well fields, the Greenbrook Well Field. Here the influence of salt reduction BMPs on subsurface water quality are examined by documenting changes in pore water Cl- concentrations and stored salt mass in vadose zone core samples collected at sites near the well field both before and after the implementation of the BMPs. The data indicate that ~6 years after salt reduction measures were initiated, average pore water Cl- concentration and average cumulative stored chloride mass in the vadose zone had decreased by approximately 60% and 40%, respectively. Groundwater samples collected from shallow monitoring wells installed at each field site showed similar post-BMP reductions in shallow groundwater Cl- concentration (~35%). Long-term (1973-2022) trends in raw water Cl- concentration data from the deeper public drinking water supply wells clearly demonstrate a slow, time-lagged response of the municipal supply wells to the salt reduction BMPs. The combined results suggest that controlled reductions in road salt applications within vulnerable, capture zone regions of public supply wells can reduce the impact of road salt deicing practices on municipal groundwater supplies over time.

Understanding the dynamics of chemsex among men who have sex with men, male sex workers and transgender women in Dhaka, Bangladesh: a multiphase sequential mixed-method research protocol

INTRODUCTION

Chemsex is defined as drug use to enhance sexual pleasure. Global literature illustrated the pervasiveness of chemsex among men who have sex with men (MSM) and transgender women (hijra) for prolonging anal intercourse, reducing pain and intensifying pleasure, oftentimes without condoms. Global literature highlighted the association between chemsex and unsafe sexual behaviours. These circumstances warrant targeted chemsex research to explore the chemsex situation. The study aims to explore the overall dynamics of chemsex among MSM, male sex workers (MSW) and hijra in Dhaka, Bangladesh and formulate culturally relevant, context-specific, gender-sensitive and evidence-based recommendations for chemsex interventions.

METHODS AND ANALYSIS

This will be a sequential, exploratory, mixed-methods study. Data will be collected at four drop-in centres in Dhaka in three phases. To explore issues related to chemsex, the formative phase (phase 1) will generate evidence on the overall dynamics of chemsex through a literature review and qualitative interviews. Qualitative data will be manually analysed using thematic analysis. In phase 2, a cross-sectional survey will be conducted among 458 MSM, male sex workers and hijra to measure the prevalence, reasons and sexual risk behaviour associated with chemsex. In phase 3, qualitative interviews will be conducted with the participants involved in chemsex, service providers and relevant stakeholders to add qualitative depth to survey responses. In this phase, service provision will also be investigated for people engaging in chemsex. Moreover, based on the findings of phases 1 and 2, and qualitative interviews of phase 3, a preliminary chemsex intervention model will be developed through a series of intervention design workshops.

ETHICS AND DISSEMINATION

Ethical approval has been attained from the Ethical Review Committee of icddr,b. Informed consent will be obtained from the participants, and confidentiality will be maintained during data collection and storage. Findings will be disseminated via several platforms including dissemination seminars, scientific articles and study report.

Are we ready for a sustainable approach? A qualitative study of the readiness of the public health system to provide STI services to the key populations at risk of HIV in Bangladesh

INTRODUCTION

In Bangladesh, sexually transmitted infection (STI) services are available for all populations in public health facilities. However, STI services for key populations (KPs) at risk of HIV need specifically designed approaches that are predominantly administered to KPs through donor-supported service centers operated by non-government organizations (NGOs) and community-based organisations (CBOs). However, the steady decline in donor funding warrants a sustainable transition of STI services for the KPs into public health facilities. This article aimed to explore the service availability and readiness of public health facilities to provide STI services for the KPs.

METHODS

This qualitative study explored the service availability and readiness of public health facilities in three districts of Bangladesh by adapting the Service Availability and Readiness Assessment tool. We conducted 34 in-depth interviews,11 focus group discussions with KPs, and 29 key-informant interviews with healthcare providers, researchers, programme implementers and policy planners, in addition to series of direct observations at the public healthcare facilities. Data were analysed through thematic analysis, and categorised in relation to the WHO building blocks.

RESULTS

This study revealed that the public health system was generally not ready to serve the KPs' needs in terms of providing them with quality STI services. The 'service delivery' component, which is the most crucial facet of the public health system, was not ready to provide STI services to KPs. Findings also indicated that health workforce availability was limited in the primary and secondary healthcare layers but adequate in the tertiary layer, but needed to be oriented on providing culturally sensitised treatment. Counseling, an essential component of STI services, was neither ready nor available. However, health information systems and a few other components were partially ready, although this warrants systematic approaches to address these challenges.

CONCLUSION

The findings show that public health facilities are yet to be fully ready to render STI services to KPs, especially in terms of service delivery and human and health resources. Therefore, it is not only integral to mobilize communities towards the uptake of public health services, but health systems need to be prepared to cater to their needs.

Reduction of household air pollution through clean fuel intervention and recovery of cellular immune balance

BACKGROUND

We conducted a clean fuel intervention trial (Bangladesh Global Environmental and Occupational Health (GEOHealth) (NCT02824237) with liquefied petroleum gas (LPG) for 26 months among rural Bangladeshi women chronically exposed to household air pollution (HAP) from biomass fuel (BMF) use. We aimed to evaluate the effect of HAP reduction following LPG intervention on immune response outcome.

METHODS

We supplied LPG cook stove and refills in cylinder in 200 households for 26 months. We measured personal exposure to HAP [particulate matter 2.5 (PM2·5), black carbon (BC) and carbon monoxide (CO)] in 200 women (main cook) by personal monitors at pre- and post-intervention. Immune function was assessed before and after intervention, in blood collected within 2 weeks of HAP measurements. Primary endpoints included reduction in HAP, lymphocyte proliferation and oxidative stress response, and alterations in T and B cell proportions.

FINDINGS

Exclusive LPG use for 26 months resulted in significant reduction in PM2·5 (43.5%), BC (13%) and CO (48%) exposure in the women. For one unit decrease in BC, Treg cells and memory B cells increased by 7% and 34% respectively, in the peripheral circulation. One unit decrease in CO was significantly associated with increase in early B cells and plasmablasts by 66% and 5% respectively. For one unit decrease in BC, percent-dividing cells, proliferation and expansion indices increased by 2%, 0.4%, and 1%, respectively.

INTERPRETATION

Reduced personal exposure to HAP through clean fuel intervention was related to a return towards cellular immune balance.

Community based peer-led TB screening intervention: an innovative approach to increase TB knowledge, presumptive case identification, and referral among sexual minority people in urban Bangladesh

INTRODUCTION

One of the contributors to tuberculosis (TB) burden among vulnerable populations, such as sexual minority people, is the delay in case finding and notification. Given their socially excluded, hard-to-reach nature, community-led approaches need to be introduced to facilitate their screening of TB symptoms and their subsequent referral to TB healthcare providers. This article aimed to explore the existing challenges surrounding TB screening and referral, and the implementation facilitators and barriers of the proposed community-based TB screening model for sexual minority people in Dhaka, Bangladesh.

METHODS

This study followed the quasi-experimental design using mixed methods (i.e., qualitative and quantitative) approach. The study participants who were also a part of the community-led TB screening model included sexual minority people enrolled in HIV prevention interventions. In addition to quantitative inquiry, in-depth interviews were conducted on sexual minority people, focus group discussions were also conducted on them and HIV prevention service providers, and key-informant interviews were conducted on service providers, programmatic experts and TB researchers. Data were analyzed using content, contextual and thematic approaches.

RESULTS

The 'Six Steps in Quality Intervention Development' framework was used to guide the development of the community-based TB screening model. In Step 1 (identifying the problem), findings revealed low rates of TB screening among sexual minority people enrolled in the HIV prevention intervention. In Step 2 (identifying contextual factors for change), various individual, and programmatic factors were identified, which included low knowledge, low-risk perception, prioritization of HIV services over TB, and stigma and discrimination towards these populations. In Step 3 (deciding change mechanism), community-based screening approaches were applied, thus leading to Step 4 (delivery of change mechanism) which designed a community-based approach leveraging the peer educators of the HIV intervention. Step 5 (testing intervention) identified some barriers and ways forward for refining the intervention, such as home-based screening and use of social media. Step 6 (collecting evidence of effectiveness) revealed that the main strength was its ability to engage peer educators.

CONCLUSION

This study indicates that a community-based peer-led TB screening approach could enhance TB screening, presumptive TB case finding and referral among these populations. Therefore, this study recommends that this approach should be incorporated to complement the existing TB program.

Establishing a surveillance system on sexual and reproductive health and rights (SRHR) of key populations (KPs) at risk of compromised outcome of SRHR- A protocol for a mixed-method study

Background

Key populations (KPs) who are at risk of compromised situation of sexual and reproductive health and rights in Bangladesh constitute including males having sex with males, male sex workers, transgender women (locally known as hijra) and female sex workers. Globally, these key populations experience various sexual and reproductive health and rights burdens and unmet needs for ailments such as sexually transmitted infections including Neisseria Gonorrhoea, Chlamydia Trachomatis and human papillomavirus. Most key population focused interventions around the world, including Bangladesh, primarily address human immune deficiency virus and sexually transmitted infections-related concerns and provide syndromic management of sexually transmitted infections, other sexual and reproductive health and rights issues are remained overlooked that creates a lack of information in the related areas. There is currently no systematic research in Bangladesh that can produce representative data on sexual and reproductive health and rights among key populations, investigates their sexual and reproductive health and rights needs, how their needs evolve, and investigate underlying factors of sexual and reproductive health and rights issues that is crucial for informing more sexual and reproductive health and rights-friendly interventions for key populations. Keeping all these issues in mind, we are proposing to establish a sexual and reproductive health and rights surveillance system for key populations in Bangladesh.

Method

The sexual and reproductive health and rights surveillance system will be established in Dhaka for males having sex with males, male sex workers and transgender women, and the other in Jashore for female sex workers. The duration will be for 3 years and data will be collected twice, in year one and year two adopting a mixed method repeated cross-sectional design. All key populations 15 years and above will be sampled. Behavioural data will be collected adopting a face-to-face technique and then biological samples will be collected. Those who will be found positive for human papillomavirus, will be referred to a government hospital for treatment. Free treatment will be provided to those who will be found positive for other sexually transmitted infections. In total, 2,240 key populations will be sampled. Written assent/consent will be taken from everyone. Data will be entered by Epi-Info and analysed by Stata. Report will be produced in every year.

Discussion

This surveillance system will be the first of its kind to systematically assess the situation of sexual and reproductive health and rights among selected key populations in Bangladesh. It is expected that this study will provide insights needed for improving the existing sexual and reproductive health and rights intervention modalities for these vulnerable and marginalized key populations.

Establishing a surveillance system on sexual and reproductive health and rights (SRHR) of key populations (KPs) at risk of compromised outcome of SRHR- A protocol for a mixed-method study

BACKGROUND

Key populations (KPs) who are at risk of compromised situation of sexual and reproductive health and rights in Bangladesh constitute including males having sex with males, male sex workers, transgender women (locally known as hijra) and female sex workers. Globally, these key populations experience various sexual and reproductive health and rights burdens and unmet needs for ailments such as sexually transmitted infections including Neisseria Gonorrhoea, Chlamydia Trachomatis and human papillomavirus. Most key population focused interventions around the world, including Bangladesh, primarily address human immune deficiency virus and sexually transmitted infections-related concerns and provide syndromic management of sexually transmitted infections, other sexual and reproductive health and rights issues are remained overlooked that creates a lack of information in the related areas. There is currently no systematic research in Bangladesh that can produce representative data on sexual and reproductive health and rights among key populations, investigates their sexual and reproductive health and rights needs, how their needs evolve, and investigate underlying factors of sexual and reproductive health and rights issues that is crucial for informing more sexual and reproductive health and rights-friendly interventions for key populations. Keeping all these issues in mind, we are proposing to establish a sexual and reproductive health and rights surveillance system for key populations in Bangladesh.

METHOD

The sexual and reproductive health and rights surveillance system will be established in Dhaka for males having sex with males, male sex workers and transgender women, and the other in Jashore for female sex workers. The duration will be for 3 years and data will be collected twice, in year one and year two adopting a mixed method repeated cross-sectional design. All key populations 15 years and above will be sampled. Behavioural data will be collected adopting a face-to-face technique and then biological samples will be collected. Those who will be found positive for human papillomavirus, will be referred to a government hospital for treatment. Free treatment will be provided to those who will be found positive for other sexually transmitted infections. In total, 2,240 key populations will be sampled. Written assent/consent will be taken from everyone. Data will be entered by Epi-Info and analysed by Stata. Report will be produced in every year.

DISCUSSION

This surveillance system will be the first of its kind to systematically assess the situation of sexual and reproductive health and rights among selected key populations in Bangladesh. It is expected that this study will provide insights needed for improving the existing sexual and reproductive health and rights intervention modalities for these vulnerable and marginalized key populations.

Verbal autopsy analysis of childhood deaths in rural Gambia

BACKGROUND

In low-resource settings, it is challenging to ascertain the burden and causes of under-5 mortality as many deaths occur outside health facilities. We aimed to determine the causes of childhood deaths in rural Gambia using verbal autopsies (VA).

METHODOLOGY

We used WHO VA questionnaires to conduct VAs for deaths under-5 years of age in the Basse and Fuladu West Health and Demographic Surveillance Systems (HDSS) in rural Gambia between September 01, 2019, and December 31, 2021. Using a standardized cause of death list, two physicians assigned causes of death and discordant diagnoses were resolved by consensus.

RESULTS

VAs were conducted for 89% (647/727) of deaths. Of these deaths, 49.5% (n = 319) occurred at home, 50.1% (n = 324) in females, and 32.3% (n = 209) in neonates. Acute respiratory infection including pneumonia (ARIP) (33.7%, n = 137) and diarrhoeal diseases (23.3%, n = 95) were the commonest primary causes of death in the post-neonatal period. In the neonatal period, unspecified perinatal causes of death (34.0%, n = 71) and deaths due to birth asphyxia (27.3%, n = 57) were the commonest causes of death. Severe malnutrition (28.6%, n = 185) was the commonest underlying cause of death. In the neonatal period, deaths due to birth asphyxia (p-value<0.001) and severe anaemia (p-value = 0.03) were more likely to occur at hospitals while unspecified perinatal deaths (p-value = 0.01) were more likely to occur at home. In the post-neonatal period, deaths due to ARIP (p-value = 0.04) and diarrhoeal disease (p-value = 0.001) were more likely to occur among children aged 1-11 months and 12-23 months respectively.

CONCLUSION

According to VA analysis of deaths identified within two HDSS in rural Gambia, half of deaths amongst children under-5 in rural Gambia occur at home. ARIP and diarrhoea, and the underlying cause of severe malnutrition remain the predominant causes of child mortality. Improved health care and health-seeking behaviour may reduce childhood deaths in rural Gambia.

An uncharted territory of sexualized drug use: exploring the dynamics of chemsex among young and adolescent MSM including self-identified gay men in urban Dhaka, Bangladesh

Global and local literature depicted the pervasiveness of chemsex among men who have sex with men (MSM), yet there is limited evidence on adolescents and youth. Though literature showed their engagement in chemsex, further exploration is warranted about their socio-sexual contexts and implications. Therefore, this article explored the contexts and implications of chemsex on young and adolescent MSM. This article is extracted from qualitative research evidence, and research data are triangulated by programmatic evidence on adolescent and young MSM from two ongoing pilot interventions. The key motivational factors for engaging in chemsex were primarily rooted in the dynamics of their peer networks. Specifically, the onset of drug use is predominantly attributed to curiosity toward experimentation with methamphetamine, peer influence, propensity to lose weight, and increasing courage to approach potential sexual partners. Moreover, they continued taking drugs as it enhanced their sexual performance, thus perpetuating chemsex. Additionally, the findings revealed several sexual implications of methamphetamine, e.g., bolstering their sexual "stamina," increasing their propensity toward sexual violence, and reducing their decision-making abilities and judgment, thus collectively decreasing condom use. In essence, chemsex is considerably driven by their socio-sexual contexts, thus perpetuating sexual risk behaviors and compromising sexual health outcomes. Therefore, harm reduction interventions targeted need to be designed keeping in mind their socio-sexual dynamics and age.

Norovirus Disease Among Children <5 Years in 3 Sub-Saharan African Countries: Findings From the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015-2018

BACKGROUND

To address a paucity of data from sub-Saharan Africa, we examined the prevalence, severity, and seasonality of norovirus genogroup II (NVII) among children <5 years old in The Gambia, Kenya, and Mali following rotavirus vaccine introduction.

METHODS

Population-based surveillance was conducted to capture medically-attended moderate-to-severe diarrhea (MSD) cases, defined as a child 0-59 months old passing ≥3 loose stools in a 24-hour period with ≥1 of the following: sunken eyes, poor skin turgor, dysentery, intravenous rehydration, or hospitalization within 7 days of diarrhea onset. Diarrhea-free matched controls randomly selected from a censused population were enrolled at home. Stools from cases and controls were tested for enteropathogens, including norovirus and rotavirus, by TaqMan quantitative polymerase chain reaction (PCR) and conventional reverse transcription PCR. We used multiple logistic regression to derive adjusted attributable fractions (AFe) for each pathogen causing MSD, which takes into consideration the prevalence in both cases and controls, for each site and age. A pathogen was considered etiologic if AFe was ≥0.5. In further analyses focusing on the predominant NVII strains, we compared rotavirus and NVII severity using a 20-point modified Vesikari score and examined seasonal fluctuations.

RESULTS

From May 2015 to July 2018, we enrolled 4840 MSD cases and 6213 controls. NVI was attributed to only 1 MSD episode. NVII was attributed to 185 (3.8%) of all MSD episodes and was the sole attributable pathogen in 139 (2.9%); peaking (36.0%) at age 6-8 months with majority (61.2%) aged 6-11 months. MSD cases whose episodes were attributed to NVII alone compared with rotavirus alone were younger (median age, 8 vs 12 months, P < .0001) and had less severe illness (median Vesikari severity score, 9 vs 11, P = .0003) but equally likely to be dehydrated. NVII occurred year-round at all study sites.

CONCLUSIONS

Infants aged 6-11 months bear the greatest burden of norovirus disease, with NVII predominating. An early infant vaccine schedule and rigorous adherence to guidelines recommended for management of dehydrating diarrhea may offer substantial benefit in these African settings.

Clinical and Epidemiologic Features of Cryptosporidium-Associated Diarrheal Disease Among Young Children Living in Sub-Saharan Africa: The Vaccine Impact on Diarrhea in Africa (VIDA) Study

BACKGROUND

As part of the Vaccine Impact on Diarrhea in Africa (VIDA) Study, we examined the prevalence, clinical presentation, and seasonality of Cryptosporidium in children to understand its relative burden after the introduction of rotavirus vaccine.

METHODS

VIDA was a 3-year, age-stratified, matched case-control study of medically attended acute moderate-to-severe diarrhea (MSD) in children aged 0-59 months residing in censused populations at sites in Kenya, Mali, and The Gambia. Clinical and epidemiologic data were collected at enrollment, and a stool sample was tested for enteropathogens by quantitative PCR. An algorithm was created based on the organism's cycle threshold (Ct) and association with MSD to identify the subset of Cryptosporidium PCR-positive (Ct <35) cases most likely to be attributed to MSD. Clinical outcomes were assessed at 2-3 months after enrollment.

RESULTS

One thousand one hundred six (22.9%) cases of MSD and 873 controls (18.1%) were PCR positive for Cryptosporidium; 465 cases (42.0%) were considered attributable to Cryptosporidium, mostly among children 6-23 months. Cryptosporidium infections peaked in The Gambia and Mali during the rainy season, while in Kenya they did not have clear seasonality. Compared with cases with watery MSD who had a negative PCR for Cryptosporidium, cases with watery MSD attributed to Cryptosporidium were less frequently dehydrated but appeared more severely ill using a modified Vesikari scale (38.1% vs 27.0%; P < 0.001), likely due to higher rates of hospitalization and intravenous fluid administration, higher prevalence of being wasted or very thin very thin (23.4% vs 14.7%; P < 0.001), and having severe acute malnutrition (midupper arm circumference <115 mm, 7.7% vs 2.5%; P < 0.001). On follow-up, Cryptosporidium-attributed cases had more prolonged and persistent episodes (43.2% vs 32.7%; P <0 .001) and linear growth faltering (change in height-for-age z score between enrollment and follow-up: -0.29 vs -0.17; P < 0.001).

CONCLUSIONS

The burden of Cryptosporidium remains high among young children in sub-Saharan Africa. Its propensity to cause illness and further impact children longer term by compromising nutritional status early in life calls for special attention to enable appropriate management of clinical and nutritional consequences.

Prevalence, Clinical Severity, and Seasonality of Adenovirus 40/41, Astrovirus, Sapovirus, and Rotavirus Among Young Children With Moderate-to-Severe Diarrhea: Results From the Vaccine Impact on Diarrhea in Africa (VIDA) Study

BACKGROUND

While rotavirus causes severe diarrheal disease in children aged <5 years, data on other viral causes in sub-Saharan Africa are limited.

METHODS

In the Vaccine Impact on Diarrhea in Africa study (2015-2018), we analyzed stool from children aged 0-59 months with moderate-to-severe diarrhea (MSD) and without diarrhea (controls) in Kenya, Mali, and The Gambia using quantitative polymerase chain reaction. We derived the attributable fraction (AFe) based on the association between MSD and the pathogen, accounting for other pathogens, site, and age. A pathogen was attributable if the AFe was ≥0.5.The severity of attributable MSD was defined by a modified Vesikari score (mVS). Monthly cases were plotted against temperature and rainfall to assess seasonality.

RESULTS

Among 4840 MSD cases, proportions attributed to rotavirus, adenovirus 40/41, astrovirus, and sapovirus were 12.6%, 2.7%, 2.9%, and 1.9%, respectively. Attributable rotavirus, adenovirus 40/41, and astrovirus MSD cases occurred at all sites, with mVS of 11, 10, and 7, respectively. MSD cases attributable to sapovirus occurred in Kenya, with mVS of 9. Astrovirus and adenovirus 40/41 peaked during the rainy season in The Gambia, while rotavirus peaked during the dry season in Mali and The Gambia.

CONCLUSIONS

In sub-Saharan Africa, rotavirus was the most common cause of MSD; adenovirus 40/41, astrovirus, and sapovirus contributed to a lesser extent among children aged <5 years. Rotavirus- and adenovirus 40/41-attributable MSD were most severe. Seasonality varied by pathogen and location. Efforts to increase the coverage of rotavirus vaccines and to improve prevention and treatment for childhood diarrhea should continue.

Histo-Blood Group Antigen Null Phenotypes Associated With a Decreased Risk of Clinical Rotavirus Vaccine Failure Among Children <2 Years of Age Participating in the Vaccine Impact on Diarrhea in Africa (VIDA) Study in Kenya, Mali, and the Gambia

BACKGROUND

Previously studied risk factors for rotavirus vaccine failure have not fully explained reduced rotavirus vaccine effectiveness in low-income settings. We assessed the relationship between histo-blood group antigen (HBGA) phenotypes and clinical rotavirus vaccine failure among children <2 years of age participating in the Vaccine Impact on Diarrhea in Africa Study in 3 sub-Saharan African countries.

METHODS

Saliva was collected and tested for HBGA phenotype in children who received rotavirus vaccine. The association between secretor and Lewis phenotypes and rotavirus vaccine failure was examined overall and by infecting rotavirus genotype using conditional logistic regression in 218 rotavirus-positive cases with moderate-to-severe diarrhea and 297 matched healthy controls.

RESULTS

Both nonsecretor and Lewis-negative phenotypes (null phenotypes) were associated with decreased rotavirus vaccine failure across all sites (matched odds ratio, 0.30 [95% confidence interval: 0.16-0.56] or 0.39 [0.25-0.62], respectively]. A similar decrease in risk against rotavirus vaccine failure among null HBGA phenotypes was observed for cases with P[8] and P[4] infection and their matched controls. While we found no statistically significant association between null HBGA phenotypes and vaccine failure among P[6] infections, the matched odds ratio point estimate for Lewis-negative individuals was >4.

CONCLUSIONS

Our study demonstrated a significant relationship between null HBGA phenotypes and decreased rotavirus vaccine failure in a population with P[8] as the most common infecting genotype. Further studies are needed in populations with a large burden of P[6] rotavirus diarrhea to understand the role of host genetics in reduced rotavirus vaccine effectiveness.

Impact of the COVID-19 pandemic on a clinical trial of pneumococcal vaccine scheduling (PVS) in rural Gambia

The COVID-19 pandemic represents an unprecedented challenge for clinical research. The Pneumococcal Vaccine Schedules (PVS) study is a non-inferiority, interventional trial in which infants resident in 68 geographic clusters are randomised to two different schedules for pneumococcal vaccination. From September 2019 onwards, all infants resident in the study area became eligible for trial enrolment at all Expanded Programme on Immunisation (EPI) clinics in the study area. Surveillance for clinical endpoints is conducted at all 11 health facilities in the study area. PVS is conducted as a collaboration between the Medical Research Council Unit The Gambia (MRCG) at LSHTM and the Gambian Ministry of Health (MoH). The COVID-19 pandemic caused many disruptions to PVS. MRCG instructed interventional studies that participant enrolment be suspended on 26 March 2020, and a public health emergency was declared in The Gambia on 28 March 2020. Enrolment in PVS restarted on 1 July 2020 and was suspended again on 5 August 2020 after The Gambia experienced a sharp increase in COVID-19 cases in late July 2020 and restarted again on 1 September 2020. During periods of suspended enrolment of infants at EPI clinics, PVS continued safety surveillance at health facilities, albeit with disruptions. During the periods of suspended enrolment, infants who had been enrolled before 26 March 2020 continued to receive the PCV schedule to which they had been randomly allocated based on their village of residence, whereas all other infants received the standard PCV schedule. Throughout 2020 and 2021, the trial faced numerous technical and operational challenges: disruption to MoH delivery of EPI services and clinical care at health facilities; episodes of staff illness and isolation; disruption of MRCG transport, procurement, communications and human resource management; and also a range of ethical, regulatory, sponsorship, trial monitoring and financial challenges. In April 2021, a formal review concluded that the pandemic had not compromised the scientific validity of PVS and that the trial should continue as per protocol. The continuing challenges that COVID-19 poses to PVS, and other clinical trials will persist for some time.

Can oral sex be performed safely among men who have sex with men (MSM) and transgender women in Bangladesh? Challenges, complexities and the way forward

Introduction

There is currently ample research and intervention initiatives addressing anal sex and sexually transmitted infections (STIs) among gender and sexually diverse people (i.e., men who have sex with men (MSM) and transgender women). However, oral sex and oral STIs are not prioritized to the same extent, despite their concerning implications. This article aimed to delineate the underlying contexts of unprotected oral sex and the management challenges of oral STIs.

Methodology

This qualitative study constituted 30 in-depth interviews, 14 focus group discussions, and 10 key-informant interviews with gender and sexually diverse people, service providers of HIV interventions and sexuality researchers. Thematic analysis conventions were applied.

Results

Findings revealed various contexts of unprotected oral sex. In particular, we found a discordance between pleasure and protected sex where participants believed the two phenomena were mutually exclusive, therefore they did not want to compromise their pleasure by using condoms. Moreover, their low awareness, risk perception, and unchallenged misconceptions about the harms of unprotected oral sex fueled their hesitancy to use condoms during oral sex. Compared to anal sex and STIs, oral sex and STIs were less prioritized in the current HIV intervention modalities, where healthcare providers lacked adequate knowledge and training about oral sex and oral STIs, as well as their complexities.

Conclusions

In Bangladesh and several other settings, oral sex is considered a taboo, thus imbuing silence about this issue and its complexities. In this context, it is integral to eradicate the taboos and silence surrounding oral sex and oral STIs in order to strengthen the overall STI management strategy. Therefore, HIV/STI prevention programs and mainstream healthcare facilities need to underscore oral STI interventions, otherwise this issue would remain under-prioritized.

Examining the impact of dimethyl sulfide emissions on atmospheric sulfate over the continental U.S

We examine the impact of dimethylsulfide (DMS) emissions on sulfate concentrations over the continental U.S. by using the Community Multiscale Air Quality (CMAQ) model version 5.4 and performing annual simulations without and with DMS emissions for 2018. DMS emissions enhance sulfate not only over seawater but also over land, although to a lesser extent. On an annual basis, the inclusion of DMS emissions increase sulfate concentrations by 36% over seawater and 9% over land. The largest impacts over land occur in California, Oregon, Washington, and Florida, where the annual mean sulfate concentrations increase by ~25%. The increase in sulfate causes a decrease in nitrate concentration due to limited ammonia concentration especially over seawater and an increase in ammonium concentration with a net effect of increased inorganic particles. The largest sulfate enhancement occurs near the surface (over seawater) and the enhancement decreases with altitude, diminishing to 10-20% at an altitude of ~5 km. Seasonally, the largest enhancement of sulfate over seawater occurs in summer, and the lowest in winter. In contrast, the largest enhancements over land occur in spring and fall due to higher wind speeds that can transport more sulfate from seawater into land.

Characterizing variations in ambient PM2.5 concentrations at the U.S. Embassy in Dhaka, Bangladesh using observations and the CMAQ modeling system

We analyze hourly PM2.5 (particles with an aerodynamic diameter of ≤ 2.5 μm) concentrations measured at the U.S. Embassy in Dhaka over the 2016 - 2021 time period and find that concentrations are seasonally dependent with the highest occurring in winter and the lowest in monsoon seasons. Mean winter PM2.5 concentrations reached ~165-175 μg/m3 while monsoon concentrations remained ~30-35 μg/m3. Annual mean PM2.5 concentration reached ~5-6 times greater than the Bangladesh annual PM2.5 standard of 15 μg/m3. The number of days exceeding the daily PM2.5 standard of 65 μg/m3 in a year approached nearly 50%. Daily-mean PM2.5 concentrations remained elevated (>65 μg/m3) for more than 80 consecutive days. Night-time concentrations were greater than daytime concentrations. The comparison of results obtained from the Community Multiscale Air Quality (CMAQ) model simulations over the Northern Hemisphere using 108-km horizontal grids with observed data suggests that the model can reproduce the seasonal variation of observed data but underpredicts observed PM2.5 in winter months with a normalized mean bias of 13-32%. In the model, organic aerosol is the largest component of PM2.5, of which secondary organic aerosol plays a dominant role. Transboundary pollution has a large impact on the PM2.5 concentration in Dhaka, with an annual mean contribution of ~40 μg/m3.

Quantifying excess mortality during the COVID-19 pandemic in 2020 in The Gambia: a time-series analysis of three health and demographic surveillance systems

OBJECTIVES

Estimates for COVID-19-related excess mortality for African populations using local data are needed to design and implement effective control policies.

METHODS

We applied time-series analysis using data from three health and demographic surveillance systems in The Gambia (Basse, Farafenni, and Keneba) to examine pandemic-related excess mortality during 2020, when the first SARS-CoV-2 wave was observed, compared to the pre-pandemic period (2016-2019).

RESULTS

Across the three sites, average mortality during the pre-pandemic period and the total deaths during 2020 were 1512 and 1634, respectively (Basse: 1099 vs 1179, Farafenni: 316 vs 351, Keneba: 98 vs 104). The overall annual crude mortality rates per 100,000 (95% CI) were 589 (559, 619) and 599 (571, 629) for the pre-pandemic and 2020 periods, respectively. The adjusted excess mortality rate was 8.8 (-34.3, 67.6) per 100,000 person-month with the adjusted rate ratio (aRR) = 1.01 (0.94,1.11). The age-stratified analysis showed excess mortality in Basse for infants (aRR = 1.22 [1.04, 1.46]) and in Farafenni for the 65+ years age group (aRR = 1.19 [1, 1.44]).

CONCLUSION

We did not find significant excess overall mortality in 2020 in The Gambia. However, some age groups may have been at risk of excess death. Public health response in countries with weak health systems needs to consider vulnerable age groups and the potential for collateral damage.

Attendance and vaccination at immunization clinics in rural Gambia before and during the COVID-19 pandemic

INTRODUCTION

The COVID-19 pandemic has affected the delivery of essential health services, such as routine immunization. We assessed the impact of the pandemic on the uptake of routine immunization in rural Gambia.

METHODS

We collected real-time vaccine administration data in the Basse and Fuladu West Health & Demographic Surveillance Systems from September 01, 2019, to December 31, 2020. We assessed the monthly number of Expanded Program on Immunization (EPI) clinic attendances and vaccines administered, comparing data during the baseline period (September 01, 2019-March 31, 2020), COVID-19 interruption period (April 01-June 30, 2020), initial recovery period (Jul 01-September 30, 2020) and the late recovery period (October 01-December 31, 2020).

RESULTS

Compared to the baseline period, there was an overall average monthly decline of 13.4% in EPI attendance and 38.3% reduction in average monthly immunizations during the interruption period. This decrease was particularly noticeable for Bacille Calmette-Guérin (BCG) (47.2%), birth dose hepatitis B (Hep B) (46.9%), 1st dose pentavalent (Penta1) (43.1%), 1st dose pneumococcal conjugate vaccine (PCV1) (42.4%), and measles vaccines (15.5%). Comparing the late recovery to baseline period, average monthly EPI attendance was 5.3% higher, with 1.9% increase in average monthly immunizations. Monthly immunizations for BCG were 3.0% greater, 2.5% greater for Hep B, 22.7% greater for oral polio vaccine (OPV1), 2.0% less for Penta1, 19.2% less for Penta2, and 2.6% less for PCV1.

CONCLUSION

The reduced EPI attendance during the pandemic interruption period lasted only 3 months. Significant recovery in EPI attendance occurred during the late recovery period, while rates of monthly immunization returned to pre-pandemic levels for most antigens. EPI programmes should implement strategies to deliver missed antigens when infants do present to EPI clinics, aware that missed doses may be age dependent.

How have Divergent Global Emission Trends Influenced Long-range Transported Ozone to North America?

Several locations across the United States in non-compliance with the national standard for ground-level ozone (O3) are thought to have sizeable influences from distant extra-regional emission sources or natural stratospheric O3, which complicates design of local emission control measures. To quantify the amount of long-range transported O3 (LRT O3), its origin, and change over time, we conduct and analyze detailed sensitivity calculations characterizing the response of O3 to emissions from different source regions across the Northern Hemisphere in conjunction with multi-decadal simulations of tropospheric O3 distributions and changes. Model calculations show that the amount of O3 at any location attributable to sources outside North America varies both spatially and seasonally. On a seasonal-mean basis, during 1990-2010, LRT O3 attributable to international sources steadily increased by 0.06-0.2 ppb yr-1 at locations across the United States and arose from superposition of unequal and contrasting trends in individual source-region contributions, which help inform attribution of the trend evident in O3 measurements. Contributions of emissions from Europe steadily declined through 2010, while those from Asian emissions increased and remained dominant. Steadily rising NOx emissions from international shipping resulted in increasing contributions to LRT O3, comparable to those from Asian emissions in recent years. Central American emissions contribute a significant fraction of LRT O3 in southwestern United States. In addition to the LRT O3 attributable to emissions outside of North America, background O3 across the continental United States is comprised of a sizeable and spatially variable fraction that is of stratospheric origin (29-78%).

Risk factors associated with non-vaccination in Gambian children: a population-based cohort study

BACKGROUND

We determined the risk factors associated with unvaccinated children in rural Gambia.

METHODS

We conducted prospective demographic surveillance and recorded immunisations in real time in the Upper River Region, The Gambia. Analysis included residents born from 1 January 2012 to 31 December 2016. Data included age, sex, household members and relationships, migrations, births, deaths, ethnicity, residential location and birth type. Children were defined as unvaccinated at 10, 15 and 24 mo of age if they missed all primary series doses (pentavalent, oral polio and pneumococcal conjugate vaccines), secondary series (first dose measles and yellow fever vaccines) or both vaccination series, respectively. Logistic regressions measured the association between risk factors and being unvaccinated.

RESULTS

In total, 5% (1567/30 832) of infants born during the study period and who were residents at the age of 10 mo were unvaccinated. Being unvaccinated at 10 mo of age was associated with children; who did not reside with either parent (adjusted OR 2.26, 95% CI 1.60 to 3.19), whose parents were not the head of household (1.29, 1.09 to 1.52), who had experienced immigration (2.78, 1.52 to 5.08) or who were not of Mandinka ethnicity (between 1.57 and 1.85 for other ethnicities).

CONCLUSIONS

Family characteristics are associated with unimmunised children in rural Gambia. Our findings may inform strategies to increase vaccine coverage.

Arsenic exposure from drinking water and endothelial dysfunction in Bangladeshi adolescents

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide, with ∼80% of CVD-related deaths occurring in low- and middle-income countries. Growing evidence suggests that chronic arsenic exposure may contribute to CVD through its effect on endothelial function in adults. However, few studies have examined the influence of arsenic exposure on cardiovascular health in children and adolescents. To examine arsenic's relation to preclinical markers of endothelial dysfunction, we enrolled 200 adolescent children (ages 15-19 years; median 17) of adult participants in the Health Effects of Arsenic Longitudinal Study (HEALS), in Araihazar, Bangladesh. Participants' arsenic exposure was determined by recall of lifetime well usage for drinking water. As part of HEALS, wells were color-coded to indicate arsenic level (<10 μg/L, 10-50 μg/L, >50 μg/L). Endothelial function was measured by recording fingertip arterial pulsatile volume change and reactive hyperemia index (RHI) score, an independent CVD risk factor, was calculated from these measurements. In linear regression models adjusted for participant's sex, age, education, maternal education, land ownership and body weight, individuals who reported always drinking water from wells with >50 μg/L arsenic had a 11.75% lower level of RHI (95% CI: -21.26, -1.09, p = 0.03), as compared to participants who drank exclusively from wells with ≤50 μg/L arsenic. Sex-stratified analyses suggest that these associations were stronger in female participants. As compared to individuals who drank exclusively from wells with ≤50 μg/L arsenic, the use of wells with >50 μg/L arsenic was associated with 14.36% lower RHI (95% CI: -25.69, -1.29, p = 0.03) in females, as compared to 5.35% lower RHI (95% CI: -22.28, 15.37, p = 0.58) in males for the same comparison. Our results suggest that chronic arsenic exposure may be related to endothelial dysfunction in adolescents, especially among females. Further work is needed to confirm these findings and examine whether these changes may increase risk of later adverse cardiovascular health events.

Association of household air pollution with cellular and humoral immune responses among women in rural Bangladesh

Household air pollution (HAP) arising from combustion of biomass fuel (BMF) is a leading cause of morbidity and mortality in low-income countries. Air pollution may stimulate pro-inflammatory responses by activating diverse immune cells and cyto/chemokine expression, thereby contributing to diseases. We aimed to study cellular immune responses among women chronically exposed to HAP through use of BMF for domestic cooking. Among 200 healthy, non-smoking women in rural Bangladesh, we assessed exposure to HAP by measuring particulate matter 2.5 (PM2.5), black carbon (BC) and carbon monoxide (CO), through use of personal monitors RTI MicroPEM™ and Lascar CO logger respectively, for 48 h. Blood samples were collected following HAP exposure assessment and were analyzed for immunoprofiling by flow cytometry, plasma IgE by immunoassay analyzer and cyto/chemokine response from monocyte-derived-macrophages (MDM) and -dendritic cells (MDDC) by multiplex immunoassay. In multivariate linear regression model, a doubling of PM2.5 was associated with small increments in immature/early B cells (CD19+CD38+) and plasmablasts (CD19+CD38+CD27+). In contrast, a doubling of CO was associated with 1.20% reduction in CD19+ B lymphocytes (95% confidence interval (CI) = -2.36, -0.01). A doubling of PM2.5 and BC each was associated with 3.12% (95%CI = -5.85, -0.38) and 4.07% (95%CI = -7.96, -0.17) decrements in memory B cells (CD19+CD27+), respectively. Exposure to CO was associated with increased plasma IgE levels (beta(β) = 240.4, 95%CI = 3.06, 477.8). PM2.5 and CO exposure was associated with increased MDM production of CXCL10 (β = 12287, 95%CI = 1038, 23536) and CCL5 (β = 835.7, 95%CI = 95.5, 1576), respectively. Conversely, BC exposure was associated with reduction in MDDC-produced CCL5 (β = -3583, 95%CI = -6358, -807.8) and TNF-α (β = -15521, 95%CI = -28968, -2074). Our findings suggest that chronic HAP exposure through BMF use adversely affects proportions of B lymphocytes, particularly memory B cells, plasma IgE levels and functions of antigen presenting cells in rural women.

Exposure to arsenic and level of Vitamin D influence the number of Th17 cells and production of IL-17A in human peripheral blood mononuclear cells in adults

There is limited evidence on the effects of environmental exposure to arsenic (As) on the immune system in adults. In a population-based study, we have found that urinary As (UAs), and its metabolites [inorganic As (InAs), monomethylated arsenicals (MMA^+3/+5), and dimethylated arsenicals (DMA^+3/+5)] modulate or influence the number of T-helper 17 (Th17) cells and IL-17A cytokine production. In non-smoking women, we observed that UAs and DMA^+3/+5 were associated with changes in Th17 cell numbers in a nonlinear fashion. In smoking males, we found that UAs was associated with a significant decrease of Th17 cell numbers. Similar association was observed among non-smoking males. Likewise, UAs, DMA^+3/+5 and MMA^+3/+5 were associated with diminished production of IL-17A among non-smoking males. When stratified by Vitamin D levels defined as sufficient (≥20 ng/ml) and insufficient (<20 ng/ml), we found a substancial decrease in Th17 cell numbers among those with insufficient levels. Individuals with sufficient VitD levels demonstrated significant inhibition of IL-17A production in non-smoking males. Collectively, we find that exposure to As via drinking water is associated with alterations in Th17 numbers and IL-17A production, and that these associations may be modified by Vitamin D status. Our findings have significance for health outcomes associated with As exposure.

Healthcare Seeking and Access to Care for Pneumonia, Sepsis, Meningitis, and Malaria in Rural Gambia

Children with acute infectious diseases may not present to health facilities, particularly in low-income countries. We investigated healthcare seeking using a cross-sectional community survey, health facility-based exit interviews, and interviews with customers of private pharmacies in 2014 in Upper River Region (URR) The Gambia, within the Basse Health & Demographic Surveillance System. We estimated access to care using surveillance data from 2008 to 2017 calculating disease incidence versus distance to the nearest health facility. In the facility-based survey, children and adult patients sought care initially at a pharmacy (27.9% and 16.7% respectively), from a relative (23.1% and 28.6%), at a local shop or market (13.5% and 16.7%), and on less than 5% of occasions with a community-based health worker, private clinic, or traditional healer. In the community survey, recent symptoms of pneumonia or sepsis (15% and 1.5%) or malaria (10% and 4.6%) were common in children and adults. Rates of reported healthcare-seeking were high with families of children favoring health facilities and adults favoring pharmacies. In the pharmacy survey, 47.2% of children and 30.4% of adults had sought care from health facilities before visiting the pharmacy. Incidence of childhood disease declined with increasing distance of the household from the nearest health facility with access to care ratios of 0.75 for outpatient pneumonia, 0.82 for hospitalized pneumonia, 0.87 for bacterial sepsis, and 0.92 for bacterial meningitis. In rural Gambia, patients frequently seek initial care at pharmacies and informal drug-sellers rather than community-based health workers. Surveillance underestimates disease incidence by 8-25%.

Urinary arsenic and relative telomere length in 5-7 year old children in Bangladesh

BACKGROUND

Telomere length has been associated with the occurrence and progression of common chronic and age-related diseases, and in younger populations, may represent a biomarker of disease susceptibility. Early childhood is a critical period for telomere biology as this period is characterized by a rapid decline in telomere length due to a large turnover of highly proliferative cells and may represent a period of unique sensitivity to environmental insults. Arsenic (As) exposure has been associated with both telomere lengthening and shortening in adults and children and some evidence suggests the effects may differ by level and timing of exposure.

OBJECTIVES

Given the lack of clarity across studies, we investigated the association between urinary As and leukocyte telomere length among 476 five- to seven-year-old children enrolled in the Bangladesh Environmental Research in Children's Health (BiRCH) cohort.

METHODS

In a series of multivariable models, adjusted for key covariates, we examined associations between urinary As and relative telomere length (RTL) of whole blood DNA.

RESULTS

We observed small but consistent, negative associations between urinary As and RTL, such that a doubling of urinary As was associated with a -0.017 (95% CI: -0.030, -0.005; p = 0.0056) decrease in RTL, in fully adjusted models. We also observed a somewhat stronger inverse relationship between urinary As concentration and RTL among children born to fathers ≥ 30 years of age at the time of birth, than those < 30 years; however, we did not observe a statistically significant interaction.

DISCUSSION

Our study suggests that As influences RTL, with detectable associations in early to mid-childhood. Further studies are needed to confirm our findings and investigate the potential long-term impacts of telomere shortening in childhood on later life health outcomes. Additional studies exploring how dose and timing of exposure may relate to RTL are critical to understanding As's relationship to telomere length.

Improving the representation of HONO chemistry in CMAQ and examining its impact on haze over China

We compare Community Multiscale Air Quality (CMAQ) model predictions with measured nitrous acid (HONO) concentrations in Beijing, China for December 2015. The model with the existing HONO chemistry in CMAQ severely under-estimates the observed HONO concentrations with a normalized mean bias of -97%. We revise the HONO chemistry in the model by implementing six additional heterogeneous reactions in the model: reaction of nitrogen dioxide (NO2) on ground surfaces, reaction of NO2 on aerosol surfaces, reaction of NO2 on soot surfaces, photolysis of aerosol nitrate, nitric acid displacement reaction, and hydrochloric acid displacement reaction. The model with the revised chemistry substantially increases HONO predictions and improves the comparison with observed data with a normalized mean bias of -5%. The photolysis of HONO enhances day-time hydroxyl radical by almost a factor of two. The enhanced hydroxyl radical concentrations compare favourably with observed data and produce additional sulfate via the reaction with sulfur dioxide, aerosol nitrate via the reaction with nitrogen dioxide, and secondary organic aerosols via the reactions with volatile organic compounds. The additional sulfate stemming from revised HONO chemistry improves the comparison with observed concentration; however, it does not close the gap between model prediction and the observation during polluted days.

Drug resistance pattern among ART-naive clients attending an HIV testing and counseling center in Dhaka, Bangladesh

In Bangladesh, antiretroviral therapy (ART) is provided without screening drug resistance-associated mutations (DRM) among people living with HIV, while DRM might emerge and transmit to the newly infected individual. The present study was aimed to identify DRM among ART-naive clients from an HIV testing and counseling (HTC) center in the initial stages of ART programs. Randomly selected (n = 64) archived plasma samples were used for the pol gene amplification and sequencing by sanger technology. Recovered sequences (n = 10) were genotyped using HIV genotyping tools of NCBI and analyzed using the Stanford University HIV drug resistance database (hivdb.stanford.edu). Various genotypes with a number of DRM were identified in HTC clients, who belonged to different risk groups based on behavioral data. The drug resistance algorithm showed that all samples were fully resistant to tipranavir/ritonavir drugs except for one intermediate resistance. Despite the small sample size, our understanding from this study warrants an ART policy with a DRM monitoring system for the country.

Impact of alien fishes on the distribution pattern of indigenous freshwater fishes of Punjab, Pakistan

Pakistan is the country with mega freshwater fish diversity of native and alien species. In the presence of enormous native fishes varies species of exotic fishes have been introduced into the freshwater bodies of Pakistan which are competing with native freshwater fish fauna and making them deprive of food and habitat as well. Intentional or accidental introductions of animals, plants and pathogens away from their native niche is considered as major leading problem for biodiversity of invaded habitat. Three years study (from January 2017 to December 2019) was conducted in freshwater bodies of Province Punjab, Pakistan. Study was designed to know exotic species impacts on the distribution of native species of fishes. During current survey a total of 68 (indigenous and exotic) fish species belonging to 14 families were recorded from head Qadirabad, head Baloki, Islam headworks and Rasul barrage. Statistical analysis showed that Shannon-Wiener diversity index was the highest (1.41) at both Rasul barrage and Islam headworks but, invasive species were present in very less number in these study sites i.e. Oreochromis mozambicus, O. niloticus, Hypophthalmichthys nobilis, Carassius auratus, Ctenophryngdon idella, Cyprinus carpio and H. molitrix. The diversity index showed that comparatively low diversity was present in both area head Qadirabad (1.30) and head Baloki (1.4) due to high pressure of invasive species. Direct observation of species and statistical analysis showed that aliens' species produced negative impact on the local fish fauna diversity, evenness, and numbers. It is concluded that many factors are impacts on the diversity of native fishes, but alien (invasive) species also play a major role to reduction of native species, because aliens' species produce competition for native species. So it is urgent need to analysis the aliens and native food web and roosting sites in Pakistan, in future.

The Community Multiscale Air Quality (CMAQ) model versions 5.3 and 5.3.1: system updates and evaluation

The Community Multiscale Air Quality (CMAQ) model version 5.3 (CMAQ53), released to the public in August 2019 and followed by version 5.3.1 (CMAQ531) in December 2019, contains numerous science updates, enhanced functionality, and improved computation efficiency relative to the previous version of the model, 5.2.1 (CMAQ521). Major science advances in the new model include a new aerosol module (AERO7) with significant updates to secondary organic aerosol (SOA) chemistry, updated chlorine chemistry, updated detailed bromine and iodine chemistry, updated simple halogen chemistry, the addition of dimethyl sulfide (DMS) chemistry in the CB6r3 chemical mechanism, updated M3Dry bidirectional deposition model, and the new Surface Tiled Aerosol and Gaseous Exchange (STAGE) bidirectional deposition model. In addition, support for the Weather Research and Forecasting (WRF) model's hybrid vertical coordinate (HVC) was added to CMAQ53 and the Meteorology-Chemistry Interface Processor (MCIP) version 5.0 (MCIP50). Enhanced functionality in CMAQ53 includes the new Detailed Emissions Scaling, Isolation and Diagnostic (DESID) system for scaling incoming emissions to CMAQ and reading multiple gridded input emission files. Evaluation of CMAQ531 was performed by comparing monthly and seasonal mean daily 8 h average (MDA8) O₃ and daily PM_2.5 values from several CMAQ531 simulations to a similarly configured CMAQ521 simulation encompassing 2016. For MDA8 O₃, CMAQ531 has higher O₃ in the winter versus CMAQ521, due primarily to reduced dry deposition to snow, which strongly reduces wintertime O₃ bias (2-4 ppbv monthly average). MDA8 O₃ is lower with CMAQ531 throughout the rest of the year, particularly in spring, due in part to reduced O₃ from the lateral boundary conditions (BCs), which generally increases MDA8 O₃ bias in spring and fall ( 0.5 μg m^-3). For daily 24 h average PM_2.5, CMAQ531 has lower concentrations on average in spring and fall, higher concentrations in summer, and similar concentrations in winter to CMAQ521, which slightly increases bias in spring and fall and reduces bias in summer. Comparisons were also performed to isolate updates to several specific aspects of the modeling system, namely the lateral BCs, meteorology model version, and the deposition model used. Transitioning from a hemispheric CMAQ (HCMAQ) version 5.2.1 simulation to a HCMAQ version 5.3 simulation to provide lateral BCs contributes to higher O₃ mixing ratios in the regional CMAQ simulation in higher latitudes during winter (due to the decreased O₃ dry deposition to snow in CMAQ53) and lower O₃ mixing ratios in middle and lower latitudes year-round (due to reduced O₃ over the ocean with CMAQ53). Transitioning from WRF version 3.8 to WRF version 4.1.1 with the HVC resulted in consistently higher (1.0-1.5 ppbv) MDA8 O₃ mixing ratios and higher PM_2.5 concentrations (0.1-0.25 μg m^-3) throughout the year. Finally, comparisons of the M3Dry and STAGE deposition models showed that MDA8 O₃ is generally higher with M3Dry outside of summer, while PM_2.5 is consistently higher with STAGE due to differences in the assumptions of particle deposition velocities to non-vegetated surfaces and land use with short vegetation (e.g., grasslands) between the two models. For ambient NH₃, STAGE has slightly higher concentrations and smaller bias in the winter, spring, and fall, while M3Dry has higher concentrations and smaller bias but larger error and lower correlation in the summer.

Exposure to household air pollutants and endothelial dysfunction in rural Bangladesh: A cross-sectional study

More than one third of world's population use biomass fuel for cooking that has been linked to an array of adverse health hazards including cardiovascular mortality and morbidity. As part of Bangladesh Global Environmental and Occupational Health (GEO Health) project, we assessed whether household air pollution (HAP) was associated with dysfunction in microvascular circulation (measured by reactive hyperemia index [RHI]).

METHODS

We measured exposure to HAP (particulate matter [PM2.5], carbon monoxide [CO], and black carbon [BC]) for 48 hours of 200 healthy nonsmoker adult females who used biomass fuel for cooking. Exposure to PM2.5 and BC were measured using personal monitor, RTI MicroPEM (RTI International, NC) with an internal filter that had been both pre- and post-weighed to capture the deposited pollutants concentration. Lascar CO logger was used to measure CO. Endothelial function was measured by forearm blood flow dilatation response to brachial artery occlusion using RHI based on peripheral artery tonometry. A low RHI score (<1.67) indicates impaired endothelial function.

RESULTS

Average 48 hours personal exposure to PM2.5 and BC were 144.15 μg/m3 (SD 61.26) and 6.35 μg/m3 (SD 2.18), respectively. Interquartile range for CO was 0.73 ppm (0.62-1.35 ppm). Mean logarithm of RHI (LnRHI) was 0.57 in current data. No statistically significant association was observed for LnRHI with PM2.5 (odds ratio [OR] = 0.97; 95% confidence interval [CI] = 0.92, 1.01; P = 0.16), BC (OR = 0.85; 95% CI = 0.72, 1.01; P = 0.07), and CO (OR = 0.89; 95% CI = 0.64, 1.25; P = 0.53) after adjusting for potential covariates.

CONCLUSIONS

In conclusion, HAP was not associated with endothelial dysfunction among nonsmoking females in rural Bangladesh who used biomass fuel for cooking for years.

Exposure to metal mixtures in relation to blood pressure among children 5-7 years old: An observational study in Bangladesh

Hypertension in later life, a significant risk factor for cardiovascular disease, has been linked to elevated blood pressure in early life. Exposure to metals may influence childhood blood pressure; however, previous research is limited and has mainly focused on evaluating the toxicity of single metal exposures. This study evaluates the associations between exposure to metal mixtures and blood pressure among Bangladeshi children age 5-7 years.

METHODS

We investigated the associations of 17 toenail metal concentrations with blood pressure using linear regression models. Principal component analysis (PCA), weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) were conducted as secondary analyses.

RESULTS

Associations were observed for selenium with diastolic blood pressure (per doubling of exposure β = 2.91, 95% confidence interval [CI] = 1.08, 4.75), molybdenum with systolic (β = 0.33, 95% CI = 0.05, 0.61) and diastolic blood pressure (β = 0.39, 95% CI = 0.12, 0.66), tin with systolic blood pressure (β = -0.33, 95% CI = -0.60, -0.06), and mercury with systolic (β = -0.83, 95% CI = -1.49, -0.17) and diastolic blood pressure (β = -0.89, 95% CI = -1.53, -0.26). Chromium was associated with diastolic blood pressure among boys only (β = 1.10, 95% CI = 0.28, 1.92, P for interaction = 0.02), and copper was associated with diastolic blood pressure among girls only (β = -1.97, 95% CI = -3.63, -0.32, P for interaction = 0.01). These findings were largely robust to the secondary analyses that utilized mixture modeling approaches (PCA, WQS, and BKMR).

CONCLUSIONS

Future prospective studies are needed to investigate further the impact of early life exposure to metal mixtures on children's blood pressure trajectories and cardiovascular disease risk later in life.

Understanding the Barriers of HIV Testing Services for Men Who Have Sex With Men and Transgender Women in Bangladesh: A Qualitative Study

Coverage of HIV testing services (HTS) is generally low among men who have sex with men (MSM) and transgender women (hijra) in Bangladesh, thus impeding the national goal of attaining the 90-90-90 target. In this context, this article delineates HTS uptake barriers among these populations. This qualitative study entailed 30 in-depth interviews, six focus groups and seven key-informant interviews with purposively selected MSM and hijra, alongside service providers. Participants cited individual and interpersonal barriers such as low risk perception and misconceptions about HIV testing, programmatic barriers such as knowledge gaps among peer service providers, as well as community and structural barriers such as the criminalization and stigmatization of male-to-male sex. Considering these contexts, it is essential for stakeholders to improve the HTS modality using multipronged approaches to address the multifaceted barriers of HTS uptake.

Genomic diversity of Escherichia coli from healthy children in rural Gambia

Little is known about the genomic diversity of Escherichia coli in healthy children from sub-Saharan Africa, even though this is pertinent to understanding bacterial evolution and ecology and their role in infection. We isolated and whole-genome sequenced up to five colonies of faecal E. coli from 66 asymptomatic children aged three-to-five years in rural Gambia (n = 88 isolates from 21 positive stools). We identified 56 genotypes, with an average of 2.7 genotypes per host. These were spread over 37 seven-allele sequence types and the E. coli phylogroups A, B1, B2, C, D, E, F and Escherichia cryptic clade I. Immigration events accounted for three-quarters of the diversity within our study population, while one-quarter of variants appeared to have arisen from within-host evolution. Several isolates encode putative virulence factors commonly found in Enteropathogenic and Enteroaggregative E. coli, and 53% of the isolates encode resistance to three or more classes of antimicrobials. Thus, resident E. coli in these children may constitute reservoirs of virulence- and resistance-associated genes. Moreover, several study strains were closely related to isolates that caused disease in humans or originated from livestock. Our results suggest that within-host evolution plays a minor role in the generation of diversity compared to independent immigration and the establishment of strains among our study population. Also, this study adds significantly to the number of commensal E. coli genomes, a group that has been traditionally underrepresented in the sequencing of this species.

Effect of bromine and iodine chemistry on tropospheric ozone over Asia-Pacific using the CMAQ model

Recent studies have focused on the chemistry of tropospheric halogen species which are able to deplete tropospheric ozone (O₃). In this study, the effect of bromine and iodine chemistry on tropospheric O₃ within the annual cycle in Asia-Pacific is investigated using the CMAQ model with the newly embedded bromine and iodine chemistry and a blended and customized emission inventory considering marine halogen emission. Results indicate that the vertical profiles of bromine and iodine species show distinct features over land/ocean and daytime/nighttime, related to natural and anthropogenic emission distributions and photochemical reactions. The halogen-mediated O₃ loss has a strong seasonal cycle, and reaches a maximum of -15.9 ppbv (-44.3%) over the ocean and -13.4 ppbv (-38.9%) over continental Asia among the four seasons. Changes in solar radiation, dominant wind direction, and nearshore chlorophyll-a accumulation all contribute to these seasonal differences. Based on the distances to the nearest coastline, the onshore and offshore features of tropospheric O₃ loss caused by bromine and iodine chemistry are studied. Across a coastline-centric 400-km-wide belt from onshore to offshore, averaged maximum gradient of O₃ loss reaches 1.1 ppbv/100 km at surface level, while planetary boundary layer (PBL) column mean of O₃ loss is more moderate, being approximately 0.7 ppbv/100 km. Relative high halogen can be found over Tibetan Plateau (TP) and the largest O₃ loss (approximately 4-5 ppbv) in the PBL can be found between the western boundary of the domain and the TP. Halogens originating from marine sources can potentially affect O₃ concentration transported from the stratosphere over the TP region. As part of efforts to improve our understanding of the effect of bromine and iodine chemistry on tropospheric O₃, we call for more models and monitoring studies on halogen chemistry and be considered further in air pollution prevention and control policy.

Impact of dimethylsulfide chemistry on air quality over the Northern Hemisphere

We implement oceanic dimethylsulfide (DMS) emissions and its atmospheric chemical reactions into the Community Multiscale Air Quality (CMAQv53) model and perform annual simulations without and with DMS chemistry to quantify its impact on tropospheric composition and air quality over the Northern Hemisphere. DMS chemistry enhances both sulfur dioxide (SO2) and sulfate (S O 4 2 - ) over seawater and coastal areas. It enhances annual mean surface SO2 concentration by +46 pptv andS O 4 2 - by +0.33 μg/m3 and decreases aerosol nitrate concentration by -0.07 μg/m3 over seawater compared to the simulation without DMS chemistry. The changes decrease with altitude and are limited to the lower atmosphere. Impacts of DMS chemistry onS O 4 2 - are largest in the summer and lowest in the fall due to the seasonality of DMS emissions, atmospheric photochemistry and resultant oxidant levels. Hydroxyl and nitrate radical-initiated pathways oxidize 75% of the DMS while halogen-initiated pathways oxidize 25%. DMS chemistry leads to more acidic particles over seawater by decreasing aerosol pH. IncreasedS O 4 2 - from DMS enhances atmospheric extinction while lower aerosol nitrate reduces the extinction so that the net effect of DMS chemistry on visibility tends to remain unchanged over most of the seawater.

Modeling the impact of marine DMS emissions on summertime air quality over the coastal East China Seas

[1] Biogenic emission of dimethyl sulfide (DMS) from seawater is the major natural source of sulfur into the atmosphere. In this study, we use an advanced air quality model (CMAQv5.2) with DMS chemistry to examine the impact of DMS emissions from seawater on summertime air quality over China. A national scale database of DMS concentration in seawater is established based on a five-year observational record in the East China seas including the Bohai Sea, the Yellow Sea and the East China Sea. We employ a commonly used global database and also the newly developed local database of oceanic DMS concentration, calculate DMS emissions using three different parameterization schemes, and perform five different model simulations for July, 2018. Results indicate that in large coastal areas of China, the average DMS emissions flux obtained with the local database is three times higher than that resulting from the global database, with a mean value of 9.1 μmol m^-2 d^-1 in the Bohai Sea, 8.4 μmol m^-2 d^-1 in the Yellow Sea and 13.4 μmol m^-2 d^-1 in the East China Sea. The total DMS emissions flux calculated with the Nightingale scheme is 42% higher than that obtained with the Liss and Merlivat scheme, but is 15% lower than that obtained with the Wanninkhof scheme. Among the three parameterizations, results of the Liss and Merlivat scheme agree better with the ship-based observations over China's coastal waters. DMS emissions with the Liss and Merlivat parametrization increase atmospheric sulfur dioxide (SO₂) and sulfate (SO₄ ^2-) concentration over the East China seas by 6.4% and 3.3%, respectively. Our results indicate that although the anthropogenic source is still the dominant contributor of atmospheric sulfur burden in China, biogenic DMS emissions source is nonnegligible.

Developing and testing community-based tuberculosis (TB) screening intervention to increase TB referral, case detection and knowledge among sexual minority people in urban Bangladesh: a mixed-method study protocol

INTRODUCTION

Although Bangladesh is a country of generalised tuberculosis (TB) epidemic, the HIV prevalence is low among general populations, and 3.9% among key populations. Despite the high possibility of HIV-TB coinfection, scientifically tested approaches for increasing TB case detection among sexual minority people are yet to be developed and implemented in Bangladesh. Such approaches could foster service delivery linkages between communities and the government health system. Findings of this experimental research are likely to provide new insights for programme managers and policy planners for adopting a similar approach in order to enhance TB referral, thus ultimately increasing TB case detections and reducing the likelihood of TB-related mortalities and morbidities, irrespective of HIV status.

METHODS AND ANALYSIS

This operational research will follow a quasi-experimental design, applying both qualitative and quantitative methods, in two drop-in centres in three phases. Phase 1 will encompass baseline data collection and development of a community-based TB screening approach. In phase 2, the newly developed intervention will be implemented, followed by end-line data collection in phase 3. Qualitative data collection will be continued throughout the first and second phases. The baseline and end-line data will be compared both in the intervention and comparison areas to measure the impact of the intervention.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Institutional Review Board of International Centre for Diarrhoeal Disease Research, Bangladesh. The findings will be disseminated through diverse scientific forums including peer-reviewed journals, presentation at conferences and among the policy-makers for policy implication. The study started in January 2019 and will continue until June 2020.

Contribution of Particulate Nitrate Photolysis to Heterogeneous Sulfate Formation for Winter Haze in China

Nitrate and sulfate are two key components of airborne particulate matter (PM). While multiple formation mechanisms have been proposed for sulfate, current air quality models commonly underestimate its concentrations and mass fractions during northern China winter haze events. On the other hand, current models usually overestimate the mass fractions of nitrate. Very recently, laboratory studies have proposed that nitrous acid (N(III)) produced by particulate nitrate photolysis can oxidize sulfur dioxide to produce sulfate. Here, for the first time, we parameterize this heterogeneous mechanism into the state-of-the-art Community Multi-scale Air Quality (CMAQ) model and quantify its contributions to sulfate formation. We find that the significance of this mechanism mainly depends on the enhancement effects (by 1-3 orders of magnitude as suggested by the available experimental studies) of nitrate photolysis rate constant (J NO 3 - ) in aerosol liquid water compared to that in the gas phase. Comparisons between model simulations and in-situ observations in Beijing suggest that this pathway can explain about 15% (assuming an enhancement factor (EF) of 10) to 65% (assuming EF = 100) of the model-observation gaps in sulfate concentrations during winter haze. Our study strongly calls for future research on reducing the uncertainty in EF.

The Association Between Smoking and Gut Microbiome in Bangladesh

INTRODUCTION

Epidemiological studies that investigate alterations in the gut microbial composition associated with smoking are lacking. This study examined the composition of the gut microbiome in smokers compared with nonsmokers.

AIMS AND METHODS

Stool samples were collected in a cross-sectional study of 249 participants selected from the Health Effects of Arsenic Longitudinal Study in Bangladesh. Microbial DNA was extracted from the fecal samples and sequenced by 16S rRNA gene sequencing. The associations of smoking status and intensity of smoking with the relative abundance or the absence and presence of individual bacterial taxon from phylum to genus levels were examined.

RESULTS

The relative abundance of bacterial taxa along the Erysipelotrichi-to-Catenibacterium lineage was significantly higher in current smokers compared to never-smokers. The odds ratio comparing the mean relative abundance in current smokers with that in never-smokers was 1.91 (95% confidence interval = 1.36-2.69) for the genus Catenibacterium and 1.89 (95% confidence interval = 1.39-2.56) for the family Erysipelotrichaceae, the order Erysipelotrichale, and the class Erysipelotrichi (false discovery rate-adjusted p values = .0008-.01). A dose-response association was observed for each of these bacterial taxa. The presence of Alphaproteobacteria was significantly greater comparing current with never-smokers (odds ratio = 4.85, false discovery rate-adjusted p values = .04).

CONCLUSIONS

Our data in a Bangladeshi population are consistent with evidence of an association between smoking status and dosage with change in the gut bacterial composition.

IMPLICATIONS

This study for the first time examined the relationship between smoking and the gut microbiome composition. The data suggest that smoking status may play an important role in the composition of the gut microbiome, especially among individuals with higher levels of tobacco exposure.

Potential Effect of Halogens on Atmospheric Oxidation and Air Quality in China

Air pollution has been a hazard in China over recent decades threatening the health of half a billion people. Much effort has been devoted to mitigating air pollution in China leading to a significant reduction in primary pollutants emissions from 2013 to 2017, while a continuously worsening trend of surface ozone (O₃, a secondary pollutant and greenhouse gas) was observed over the same period. Atmospheric oxidation, dominated by daytime reactions involving hydroxyl radicals (OH), is the critical process to convert freshly-emitted compounds into secondary pollutants, and is underestimated in current models of China's air pollution. Halogens (chlorine, bromine, and iodine) are known to profoundly influence oxidation chemistry in the marine environment; however, their impact on atmospheric oxidation and air pollution in China is unknown. In the present study, we report for the first time that halogens substantially enhance the total atmospheric oxidation capacity in polluted areas of China, typically 10% to 20% (up to 87% in winter) and mainly by significantly increasing OH level. The enhanced oxidation along the coast is driven by oceanic emissions of bromine and iodine, and that over the inland areas by anthropogenic emission of chlorine. The extent and seasonality of halogen impact are largely explained by the dynamics of Asian monsoon, location and intensity of halogen emissions, and O₃ formation regime. The omission of halogen emissions and chemistry may lead to significant errors in historical re-assessments and future projections of the evolution of atmospheric oxidation in polluted regions.