Social connectedness and disease transmission: social organization, cohesion, village context, and infection risk in rural Ecuador

Pandemic-associated food insecurity in northern, coastal Ecuador

The COVID-19 pandemic worsened food insecurity worldwide. The aim of this study was to examine the impact of the pandemic on perceived food insecurity among households in rural Esmeraldas, Ecuador. We conducted a cross-sectional survey to characterize pandemic impacts on household livelihoods and food insecurity in five communities. Fifteen months after the pandemic began, food insecurity was reported in almost half of all households. Residents of the least-accessible community reported the greatest disruptions in food availability, while residents of more accessible communities reported greater disruption to livelihoods. These data suggests that transportation restrictions differentially impacted the least accessible rural communities.

Increasing transmission of dengue virus across ecologically diverse regions of Ecuador and associated risk factors

The distribution and intensity of viral diseases transmitted by Aedes aegypti mosquitoes, including dengue, have rapidly increased over the last century. Here, we study dengue virus (DENV) transmission across the ecologically and demographically distinct regions or Ecuador. We analyzed province-level age-stratified dengue incidence data from 2000-2019 using catalytic models to estimate the force of infection of DENV over eight decades. We found that provinces established endemic DENV transmission at different time periods. Coastal provinces with the largest and most connected cities had the earliest and highest increase in DENV transmission, starting around 1980 and continuing to the present. In contrast, remote and rural areas with reduced access, like the northern coast and the Amazon regions, experienced a rise in DENV transmission and endemicity only in the last 10 to 20 years. The newly introduced chikungunya and Zika viruses have age-specific distributions of hospital-seeking cases consistent with recent emergence across all provinces. To evaluate factors associated with geographic differences in DENV transmission potential, we modeled DENV vector risk using 11,693 Aedes aegypti presence points to the resolution of 1 hectare. In total, 56% of the population of Ecuador, including in provinces identified as having increasing DENV transmission in our models, live in areas with high risk of Aedes aegypti, with population size, trash collection, elevation, and access to water as important determinants. Our investigation serves as a case study of the changes driving the expansion of DENV and other arboviruses globally and suggest that control efforts should be expanded to semi-urban and rural areas and to historically isolated regions to counteract increasing dengue outbreaks.

Correlates of maternal depression, anxiety and functioning across an urban-rural gradient in northern Ecuador

Maternal depression remains under characterised in many low- and middle-income countries, especially in rural settings. We aimed to describe maternal depression and anxiety symptoms in rural and urban communities in northern Ecuador and to identify socioeconomic and demographic factors associated with these symptoms. Data from 508 mothers participating in a longitudinal cohort study were included. Depression and anxiety symptoms were assessed using the Hopkins Symptom Checklist (HSCL-25), and maternal psychological functioning was assessed using a checklist of daily activities. Tobit regression models were used to examine associations with sociodemographic variables and urbanicity. The median HSCL-25 score was 1.2 (IQR: 0.4) and 14% of women scored above the threshold for clinically relevant symptoms. Rural women reported similar food insecurity, less education, younger age of first pregnancy, and lower socio-economic status compared to their urban counterparts. After adjusting for these factors, rural women reported lower HSCL-25 scores compared to women lin urban areas (β = -0.48, 95%CI:0.65, -0.31). Rural residence was also associated with lower depression and anxiety HSCL-25 sub-scale scores, and similar levels of maternal functioning, compared to urban residence. Our results suggest that both household and community-level factors are risk factors for maternal depression and anxiety in this context.

Association of Social Capital With Tuberculosis: A Community-Based Cross-Sectional Analytical Study in South India

BACKGROUND

Social capital denotes the relationships, networks, norms and values in the community. A high level of social capital positively improves health through a supportive social system. Illnesses affect health and social relationships. One such disease is tuberculosis (TB), known for its social stigma. India has the highest burden of morbidity and mortality due to TB. The assessment of social capital would highlight the importance of a supportive environment in reducing the disease burden and bringing better treatment outcomes.

METHODS

A cross-sectional exploratory analytical study was conducted in two primary health centers in Puducherry between February 2020 and March 2021. Considering the feasibility and resource constraints, we assessed the social capital between 50 newly diagnosed pulmonary tuberculosis (PTB) patients, their age- and gender-matched 50 household contacts (HHCs) and 50 PTB patients who completed treatment a year before. The HHC was either the marital partner or sibling of the newly diagnosed PTB patients selected for comparison as their exposure to infection would be similar to those diseased but did not develop the illness. Social capital and its domains were assessed using the World Bank's social capital questionnaire. Sociodemographic characteristics and social capital domains were compared using a chi-squared test. Mean standardized Z-scores of the domains were compared using one-way analysis of variance (ANOVA). A p-value of <0.05 is taken as significant.

RESULTS

Most participants from each group belonged to lower socioeconomic strata and were males (80%). The overall level of social capital was low among the newly diagnosed PTB patients, especially the group and network and trust and solidarity domains. The mean standardized Z-scores of social capital were the highest among the HHCs, followed by the treatment-completed PTB patients. There was no consistent pattern, but the trust and solidarity domain showed a statistically significant difference.

CONCLUSION

A low level of social capital and its domains were seen among the newly diagnosed PTB patients. However, better scores among the HHCs and the treatment-completed patients infer a negative association between social capital and TB. Thus, higher social capital preserves and improves health. Therefore, caregivers and disease-cured patients can be utilized as a social support system for current diseased patients and improve their health status.

Increasing transmission of dengue virus across ecologically diverse regions of Ecuador and associated risk factors

The distribution and intensity of viral diseases transmitted by Aedes aegypti mosquitoes, including dengue, have rapidly increased over the last century. Ecuador is an interesting country to study drivers of dengue virus (DENV) transmission given it has multiple ecologically and demographically distinct regions. Here, we analyze province-level age-stratified dengue prevalence data from 2000-2019 using catalytic models to estimate the force of infection of DENV over eight decades and across provinces in Ecuador. We found that provinces established endemic DENV transmission at different time periods. Coastal provinces with the largest and most connected cities had the earliest and highest increase in DENV transmission, starting around 1980 and continuing to the present. In contrast, remote and rural areas with reduced access, like the northern coast and the Amazon regions, experienced a rise in DENV transmission and endemicity only in the last 10 to 20 years. The newly introduced chikungunya and Zika viruses have distinct age-specific prevalence distributions consistent with recent emergence across all provinces. We evaluated factors to the resolution of 1 hectare associated with geographic differences in vector suitability and arbovirus disease in the last 10 years by modeling 11,693 A aegypti presence points and 73,550 arbovirus cases. In total, 56% of the population of Ecuador lives in areas with high risk of Aedes aegypti. Most suitable provinces had hotspots for arbovirus disease risk, with population size, elevation, sewage connection, trash collection, and access to water as important determinants. Our investigation serves as a case study of the changes driving the expansion of DENV and other arboviruses globally and suggest that control efforts should be expanded to semi-urban and rural areas and to historically isolated regions to counteract increasing dengue outbreaks.

A Chikungunya Outbreak in a Dengue-endemic Region in Rural Northern Coastal Ecuador

Dengue virus (DENV) reemerged in the Americas in the 1980s and 1990s, whereas chikungunya virus (CHIKV) emerged in 2014. Although CHIKV produced large epidemics from 2014 to 2017, dengue fever has been the prominent arboviral disease identified through passive surveillance, bringing to question the degree to which cases are misdiagnosed. To address this concern, we conducted an active household-based surveillance of arboviral-like illnesses in six rural and remote communities in northern coastal Ecuador from May 2019 to February 2020. Although passive surveillance conducted by the Ecuadorian Ministry of Health reported only DENV cases in the region, more than 70% of the arbovirus-like illnesses detected by active surveillance in our study were positive for CHIKV. These findings underline the need for active surveillance of arboviral infections with laboratory confirmation, especially in rural communities where arboviral illnesses are more likely to be underreported.

The importance of community during rapid development: The influence of social networks on acute gastrointestinal illness in rural Ecuador

Social networks are often measured as conduits of infection. Our prior cross-sectional analyses found that denser social ties among individuals reduces transmission of acute gastrointestinal illness (AGI) in coastal Ecuador; social networks can describe both risk and protection. We extend findings to examine how social connectedness influences AGI longitudinally in Ecuador from 2007 to 2013, a time of rapid development, using a two-stage Bayesian hierarchical model to estimate multiple network effects. A larger community network of people to discuss important matters with was consistently protective against AGI over time, and a network defined by people passing time together became a stronger measure of risk, due to increasing population density and travel. These networks were interdependent: the joint effect of having a small passing time network and large important matters network reduced the odds of AGI over time (2007: OR 1.16 (95% CI: 0.94, 1.44), 2013: OR 0.56 (95% CI: 0.45, 0.71)); and synergistic: the people an individual passed time with became the people they discussed important matters with. Focus groups emphasized that with greater remoteness came greater community cohesion resulting in safer WASH practices. Social networks can enhance and reduce health differently as social infrastructure evolves, highlighting the importance of community-level factors in a period of rapid development.

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Social connectedness, a construct often represented as social networks, plays an important role in public health.

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This construct can lead to both protection from and risk of infectious diseases, particularly during rapid development.

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Two types of longitudinal social network data from Ecuador were assessed: core discussion network and passing time network.

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The two types of social connections interact and contribute differentially to the reduction of acute gastrointestinal illness.

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In more remote areas, the strength of the community structure and organization was critical for disease reduction despite minimal road access.

Assessing comparative asset-based measures of material wealth as predictors of physical growth and mortality

Social scientists and policymakers have increasingly relied on asset-based indices of household wealth to assess social disparities and to identify economically vulnerable populations in low- and middle-income countries. In the last decade, researchers have proposed a number of asset-based measures that permit global comparisons of household wealth across populations in different countries and over time. Each of these measures relies on different assumptions and indicators, and little is known about the relative performance of these measures in assessing disparities. In this study, we assess four comparative, asset-based measures of wealth-the Absolute Wealth Estimate (AWE), the International Wealth Index (IWI), the Comparative Wealth Index (CWI), and the "Standard of Living" portion of the Multi-Dimensional Poverty Index (MPI), along with a variable measuring television ownership-and compare how well each predicts health related variables such as women's BMI, children's height-for-age Z scores, and infant mortality at the household and survey level. Analyzing data from over 300 Demographic and Health surveys in 84 countries (n = 2,304,928 households), we found that AWE, IWI, CWI, MPI are all highly correlated (r = 0.7 to 0.9). However, IWI which is based on a common set of universally weighted indicators, typically best accounts for variation in all three health measures. We discuss the implications of these findings for choosing and interpreting these measures of wealth for different purposes.

Egocentric social network characteristics and cardiovascular risk among patients with hypertension or diabetes in western Kenya: a cross-sectional analysis from the BIGPIC trial

OBJECTIVES

Management of cardiovascular disease (CVD) is an urgent challenge in low-income and middle-income countries, and interventions may require appraisal of patients' social networks to guide implementation. The purpose of this study is to determine whether egocentric social network characteristics (SNCs) of patients with chronic disease in western Kenya are associated with overall CVD risk and individual CVD risk factors.

DESIGN

Cross-sectional analysis of enrollment data (2017-2018) from the Bridging Income Generation with GrouP Integrated Care trial. Non-overlapping trust-only, health advice-only and multiplex (trust and health advice) egocentric social networks were elicited for each participant, and SNCs representing social cohesion were calculated.

SETTING

24 communities across four counties in western Kenya.

PARTICIPANTS

Participants (n=2890) were ≥35 years old with diabetes (fasting glucose ≥7 mmol/L) or hypertension.

PRIMARY AND SECONDARY OUTCOMES

We hypothesised that SNCs would be associated with CVD risk status (QRISK3 score). Secondary outcomes were individual CVD risk factors.

RESULTS

Among the 2890 participants, 2020 (70%) were women, and mean (SD) age was 60.7 (12.1) years. Forty-four per cent of participants had elevated QRISK3 score (≥10%). No relationship was observed between QRISK3 level and SNCs. In unadjusted comparisons, participants with any individuals in their trust network were more likely to report a good than a poor diet (41% vs 21%). SNCs for the trust and multiplex networks accounted for a substantial fraction of variation in measures of dietary quality and physical activity (statistically significant via likelihood ratio test, adjusted for false discovery rate).

CONCLUSION

SNCs indicative of social cohesion appear to be associated with individual behavioural CVD risk factors, although not with overall CVD risk score. Understanding how SNCs of patients with chronic diseases relate to modifiable CVD risk factors could help inform network-based interventions.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT02501746; https://clinicaltrials.gov/ct2/show/NCT02501746.

The pandemic predominantly hits poor neighbourhoods? SARS-CoV-2 infections and COVID-19 fatalities in German districts

Background

Reports from the UK and the USA suggest that COVID-19 predominantly affects poorer neighbourhoods. This article paints a more complex picture by distinguishing between a first and second phase of the pandemic. The initial spread of infections and its correlation with socio-economic factors depends on how the virus first entered a country. The second phase of the pandemic begins when individuals start taking precautionary measures and governments implement lockdowns. In this phase the spread of the virus depends on the ability of individuals to socially distance themselves, which is to some extent socially stratified.

Methods

We analyse the geographical distribution of known cumulative cases and fatalities per capita in an ecological analysis across local districts in Germany distinguishing between the first and the second phase of the pandemic.

Results

In Germany, the virus first entered via individuals returning from skiing in the Alps and other international travel. In this first phase we find a positive association between the wealth of a district and infection rates and a negative association with indicators of social deprivation. During the second phase and controlling for path dependency, districts with a higher share of university-educated employees record fewer new infections and deaths and richer districts record fewer deaths, districts with a higher unemployment rate record more deaths.

Conclusion

The social stratification of Covid-19 changes substantively across the two phases of the pandemic in Germany. Only in the second phase and controlling for temporal dependence does Covid-19 predominantly hit poorer districts.

Multi-dimensional effects of the COVID-19 pandemic considering the WHO's ecological approach

At the end of 2019, a new virus named SARS-CoV-2 emerged in China, provoking coronavirus disease 2019 or COVID-19. Self-isolation and quarantine as key strategies to overcoming the spread of the disease have had major, micro, and macroscopic consequences. This commentary, therefore, seeks to review critical factors impacting the COVID-19 pandemic through the spectrum of levels, categorising effects in the WHO's ecological framework (individual, relational, community, and societal aspects). We further describe the management of the crisis at each level to help guide health personnel, communities, governments, and international policymakers in understanding how their actions fit into a larger picture as they seek to manage the crisis.

Systems Science Approaches for Global Environmental Health Research: Enhancing Intervention Design and Implementation for Household Air Pollution (HAP) and Water, Sanitation, and Hygiene (WASH) Programs

BACKGROUND

Two of the most important causes of global disease fall in the realm of environmental health: household air pollution (HAP) and poor water, sanitation, and hygiene (WASH) conditions. Interventions, such as clean cookstoves, household water treatment, and improved sanitation facilities, have great potential to yield reductions in disease burden. However, in recent trials and implementation efforts, interventions to improve HAP and WASH conditions have shown few of the desired health gains, raising fundamental questions about current approaches.

OBJECTIVES

We describe how the failure to consider the complex systems that characterize diverse real-world conditions may doom promising new approaches prematurely. We provide examples of the application of systems approaches, including system dynamics, network analysis, and agent-based modeling, to the global environmental health priorities of HAP and WASH research and programs. Finally, we offer suggestions on how to approach systems science.

METHODS

Systems science applied to environmental health can address major challenges by a) enhancing understanding of existing system structures and behaviors that accelerate or impede aims; b) developing understanding and agreement on a problem among stakeholders; and c) guiding intervention and policy formulation. When employed in participatory processes that engage study populations, policy makers, and implementers, systems science helps ensure that research is responsive to local priorities and reflect real-world conditions. Systems approaches also help interpret unexpected outcomes by revealing emergent properties of the system due to interactions among variables, yielding complex behaviors and sometimes counterintuitive results.

DISCUSSION

Systems science offers powerful and underused tools to accelerate our ability to identify barriers and facilitators to success in environmental health interventions. This approach is especially useful in the context of implementation research because it explicitly accounts for the interaction of processes occurring at multiple scales, across social and environmental dimensions, with a particular emphasis on linkages and feedback among these processes. https://doi.org/10.1289/EHP7010.

Rainfall and child weight in Uganda

We combine data from the 2006 and 2011 Uganda Demographic and Health Surveys (UDHS) with rainfall data and two waves of the Ugandan National Household Survey (UNHS) to study patterns in child weight, as measured by weight-for-height z scores (WHZ), among 3492 rural children below age 5 in Uganda. We focus on rainfall as a nutrition driver along agriculture and disease pathways. We find a positive and significant association between crop yield and WHZ, but the magnitude of this association diminishes as we control for covariates, especially the use of productivity-enhancing agricultural inputs. We find diarrheal disease to have a negative and significant association with WHZ, and modifying effects of social and environmental factors along the disease pathway. Contemporaneous rainfall is associated with a lower likelihood of diarrheal disease in areas with excess rainfall and a higher likelihood of diarrheal disease in rainfall deficit areas. Our findings reinforce calls for targeted and situation-sensitive policies to promote child nutrition.

Social patterning of acute respiratory illnesses in the Household Influenza Vaccine Evaluation (HIVE) Study 2014-2015

Social patterning of infectious diseases is increasingly recognised. Previous studies of social determinants of acute respiratory illness (ARI) have found that highly educated and lower income families experience more illnesses. Subjective social status (SSS) has also been linked to symptomatic ARI, but the association may be confounded by household composition. We examined SSS and ARI in the Household Influenza Vaccine Evaluation (HIVE) Study in 2014–2015. We used SSS as a marker of social disadvantage and created a workplace disadvantage score for working adults. We examined the association between these measures and ARI incidence using mixed-effects Poisson regression models with random intercepts to account for household clustering. In univariate analyses, mean ARI was higher among children <5 years old (P < 0.001), and females (P = 0.004) at the individual level. At the household level, mean ARI was higher for households with at least one child <5 years than for those without (P = 0.002). In adjusted models, individuals in the lowest tertile of SSS had borderline significantly higher rates of ARI than those in the highest tertile (incidence rate ratio (IRR) 1.34, 95% confidence interval (CI) 0.98–1.92). Households in the lowest tertile of SSS had significantly higher ARI incidence in household-level models (IRR 1.46, 95% CI 1.05–2.03). We observed no association between workplace disadvantage and ARI. We detected an increase in the incidence of ARI for households with low SSS compared with those with high SSS, suggesting that socio-economic position has a meaningful impact on ARI incidence.

Social cohesion and passive adaptation in relation to climate change and disease

Climate change affects biophysical processes related to the transmission of many infectious diseases, with potentially adverse consequences for the health of communities. While our knowledge of biophysical associations between meteorological factors and disease is steadily improving, our understanding of the social processes that shape adaptation to environmental perturbations lags behind. Using computational modeling methods, we explore the ways in which social cohesion can affect adaptation of disease prevention strategies when communities are exposed to different environmental scenarios that influence transmission pathways for diseases such as diarrhea. We developed an agent-based model in which household agents can choose between two behavioral strategies that offer different levels of protection against environmentally mediated disease transmission. One behavioral strategy is initially set as more protective, leading households to adopt it widely, but its efficacy is sensitive to variable weather conditions and stressors such as floods or droughts that modify the disease transmission system. The efficacy of the second strategy is initially moderate relative to the first and is insensitive to environmental changes. We examined how social cohesion (defined as average number of household social network connections) influences health outcomes when households attempt to identify an optimal strategy by copying the behaviors of socially connected neighbors who seem to have adapted successfully in the past. Our simulation experiments suggest that high-cohesion communities are able to rapidly disseminate the initially optimal behavioral strategy compared to low-cohesion communities. This rapid and pervasive change, however, decreases behavioral diversity; i.e., once a high cohesion community settles on a strategy, most or all households adopt that behavior. Following environmental changes that reduce the efficacy of the initially optimal strategy, rendering it suboptimal relative to the alternative strategy, high-cohesion communities can fail to adapt. As a result, despite faring better early in the course of computational experiments, high-cohesion communities may ultimately experience worse outcomes. In the face of uncertainty in predicting future environmental stressors due to climate change, strategies to improve effective adaptation to optimal disease prevention strategies should balance between intervention efforts that promote protective behaviors based on current scientific understanding and the need to guard against the crystallization of inflexible norms. Developing generalizable models allows us to integrate a wide range of theories multiple datasets pertaining to the relationship between social mechanisms and adaptation, which can provide further understanding of future climate change impacts. Models such as the one we present can generate hypotheses about the mechanisms that underlie the dynamics of adaptation events and suggest specific points of measurement to assess the impact of these mechanisms. They can be incorporated as modules within predictive simulations for specific socio-ecological contexts.

Mass Gatherings and Diarrheal Disease Transmission Among Rural Communities in Coastal Ecuador

Mass gatherings exacerbate infectious disease risks by creating crowded, high-contact conditions and straining the capacity of local infrastructure. While mass gatherings have been extensively studied in the context of epidemic disease transmission, the role of gatherings in incidence of high-burden, endemic infections has not been previously studied. Here, we examine diarrheal incidence among 17 communities in Esmeraldas, Ecuador, in relation to recurrent gatherings characterized using ethnographic data collected during and after the epidemiologic surveillance period (2004-2007). Using distributed-lag generalized estimating equations, adjusted for seasonality, trend, and heavy rainfall events, we found significant increases in diarrhea risk in host villages, peaking 2 weeks after an event's conclusion (incidence rate ratio, 1.21; confidence interval, adjusted for false coverage rate of ≤0.05: 1.02, 1.43). Stratified analysis revealed heightened risks associated with events where crowding and travel were most likely (2-week-lag incidence rate ratio, 1.51; confidence interval, adjusted for false coverage rate of ≤0.05: 1.09, 2.10). Our findings suggest that community-scale mass gatherings might play an important role in endemic diarrheal disease transmission and could be an important focus for interventions to improve community health in low-resource settings.

The social network context of HIV stigma: Population-based, sociocentric network study in rural Uganda

RATIONALE

HIV-related stigma profoundly affects the physical and social wellbeing of people living with HIV, as well as the community's engagement with testing, treatment, and prevention. Based on theories of stigma elaborating how it arises from the relationships between the stigmatized and the stigmatizer as well as within the general community, we hypothesized that social networks can shape HIV-related stigma.

OBJECTIVE

To estimate social network correlates of HIV-related stigma.

METHODS

During 2011-2012, we collected complete social network data from a community of 1669 adults ("egos") in Mbarara, Uganda using six culturally-adapted name generators to elicit different types of social ties ("alters"). We measured HIV-related stigma using the 9-item AIDS-Related Stigma Scale. HIV serostatus was based on self-report. We fitted linear regression models that account for network autocorrelation to estimate the association between egos' HIV-related stigma, alters' HIV-related stigma and alters' self-reported HIV serostatus, while adjusting for egos' HIV serostatus, network centrality, village size, perceived HIV prevalence, and sociodemographic characteristics.

RESULTS

The average AIDS-Related Stigma Score was 0.79 (Standard Deviation = 0.50). In the population 116 (7%) egos reported being HIV-positive, and 757 (46%) reported an HIV-positive alter. In the multivariable model, we found that egos' own HIV-related stigma was positively correlated with their alters' average stigma score (b=0.53; 95% confidence interval [CI] 0.42-0.63) and negatively correlated with having one or more HIV-positive alters (b=-0.05; 95% CI -0.10 to -0.003).

CONCLUSION

Stigma-reduction interventions should be targeted not only at the level of the individual but also at the level of the network. Directed and meaningful contact with people living with HIV may also reduce HIV-related stigma.

Spatiotemporal Error in Rainfall Data: Consequences for Epidemiologic Analysis of Waterborne Diseases

The relationship between rainfall, especially extreme rainfall, and increases in waterborne infectious diseases is widely reported in the literature. Most of this research, however, has not formally considered the impact of exposure measurement error contributed by the limited spatiotemporal fidelity of precipitation data. Here, we evaluate bias in effect estimates associated with exposure misclassification due to precipitation data fidelity, using extreme rainfall as an example. We accomplished this via a simulation study, followed by analysis of extreme rainfall and incident diarrheal disease in an epidemiologic study in Ecuador. We found that the limited fidelity typical of spatiotemporal rainfall data sets biases effect estimates towards the null. Use of spatial interpolations of rain-gauge data or satellite data biased estimated health effects due to extreme rainfall (occurrence) and wet conditions (accumulated totals) downwards by 35%-45%. Similar biases were evident in the Ecuadorian case study analysis, where spatial incompatibility between exposed populations and rain gauges resulted in the association between extreme rainfall and diarrheal disease incidence being approximately halved. These findings suggest that investigators should pay greater attention to limitations in using spatially heterogeneous environmental data sets to assign exposures in epidemiologic research.

Locals get travellers' diarrhoea too: risk factors for diarrhoeal illness and pathogenic Escherichia coli infection across an urban-rural gradient in Ecuador

OBJECTIVES

Diarrhoea is a common and well-studied cause of illness afflicting international travellers. However, traveller's diarrhoea can also result from travel between high and low disease transmission regions within a country, which is the focus of this study.

METHODS

We recruited participants for a case-control study of diarrhoea at four sites along an urban-rural gradient in Northern Ecuador: Quito, Esmeraldas, Borbón and rural communities outside of Borbón. At each of these sites, approximately 100 subjects with diarrhoea (cases) were recruited from Ministry of Health clinics and were age-matched with subjects visiting the same clinics for other complaints (controls).

RESULTS

Travellers to urban destinations had higher risk of diarrhoea and diarrhoeagenic Escherichia coli (DEC) infections. Travel to Quito was associated with diarrhoea (aOR = 2.01, 95% CI = 1.10-3.68) and travel to Guayaquil (another urban centre in Ecuador) was associated with Diffuse Adherent E. coli infection (OR = 2.09, 95% CI = 1.01-4.33). Compared to those not travelling, urban origins were also associated with greater risk of diarrhoea in Esmeraldas (aOR = 2.28, 95% CI = 1.20-4.41), and with higher risk of diarrhoeagenic E. coli infections in Quito (aOR = 2.61, 95% CI = 1.16-5.86), with >50% of travel from Quito and Esmeraldas specified to another urban destination.

CONCLUSIONS

This study suggests that individuals travelling from lower-transmission regions (rural areas) to higher transmission regions (urban centres) within a single country are at a greater risk of acquiring a diarrhoea-related illness. Investments to improve water, sanitation and hygiene conditions in urban areas could have impacts on outlying rural areas within a given country.

Sachet water quality and product registration: a cross-sectional study in Accra, Ghana

The study's objectives were to assess the extent to which packaged water producers follow product registration procedures and to assess the relationship between product registration and drinking water quality in Accra, Ghana. Following preliminary analysis of a national water quality survey, 118 packaged sachet water samples were collected by sampling all brands sold by 66 vendors. A sample of vendors was selected from two high-income and two low-income areas of Accra, Ghana. Sachet packaging and labelling details were recorded and compared to a regulatory database to assess product registration. All samples were weighed and tested for faecal indicator bacteria and selected physico-chemical parameters. Product registration numbers and brand names could be matched to regulatory records for 77 of 118 sachets (65.2%). All samples tested were compliant with national water quality standards for faecal indicator bacteria and nitrate. Brand registration was not associated with any of the quality indicators considered. The results of this study suggest that while a substantial proportion of sachet water is sold without formal product registration, the microbial quality of the unlicensed water is consistently high in Accra, Ghana. Further examination of regulatory enforcement and monitoring will be needed to ensure sustained high water quality over time.

Community perceptions of the socio-economic structural context influencing HIV and TB risk, prevention and treatment in a high prevalence area in the era of antiretroviral therapy

Following calls for targeted HIV prevention interventions in so-called “hotspots”, we explored subjective perceptions of community members in places considered to be high HIV and tuberculosis (TB) transmission areas and those with low prevalence. Although more people now have access to antiretroviral therapy (ART), some areas are still experiencing high HIV transmission rates, presenting a barrier to the elimination of HIV. A rapid qualitative assessment approach was used to access a sample of 230 people who contributed narratives of their experiences and perceptions of transmission, treatment and prevention of HIV and TB in their communities. Theoretical propositions case study strategy was used to inform and guide the thematic analysis of the data with Research Department of Epidemiology & Public Health, University College London, London, UK. Our results support the concept of linking perceived control to health through the identification of structural factors that increase communities’ sense of agency. People in these communities did not feel they had the efficacy to effect change in their milieu. The few socio-economic opportunities promote social mobility in search of better prospects which may have a negative impact on community cohesion and prevention strategies. Communities were more concerned with improving their immediate social and economic situations and prioritised this above the prevention messages. Therefore approaches that focus on changing the structural and environmental barriers to prevention may increase people’s perceived control. Multifaceted strategies that address the identified constructs of perceived control may influence the social change necessary to make structural interventions successful.

Determinants of Short-term Movement in a Developing Region and Implications for Disease Transmission

BACKGROUND

Human mobility is important for infectious disease spread. However, little is known about how travel varies by demographic groups and how this heterogeneity influences infectious disease risk.

METHODS

We analyzed 10 years of survey data from 15 communities in a remote but rapidly changing region in rural Ecuador where road development in the past 15-20 years has dramatically changed travel. We identify determinants of travel and incorporate them into an infection transmission model.

RESULTS

Individuals living in communities more remote at baseline had lower travel rates compared with less remote villages (adjusted odds ratio [OR] = 0.51; 95% confidence interval [CI] = 0.38, 0.67). Our model predicts that less remote villages are, therefore, at increased disease risk. Though road building and travel increased for all communities, this risk differential remained over 10 years of observation. Our transmission model also suggests that travelers and nontravelers have different roles in disease transmission. Adults travel more than children (adjusted OR = 1.73; 95% CI = 1.30, 2.31) and therefore disseminate infection from population centers to rural communities. Children are more likely than adults to be infected locally (attributable fraction = 0.24 and 0.09, respectively) and were indirectly affected by adult travel patterns.

CONCLUSIONS

These results reinforce the importance of large population centers for regional transmission and show that children and adults may play different roles in disease spread. Changing transportation infrastructure and subsequent economic and social transitions are occurring worldwide, potentially causing increased regional risk of disease.

Social Influence in Liver Fluke Transmission: Application of Social Network Analysis of Food Sharing in Thai Isaan Culture

In northeastern Thai (Isaan) culture traditional raw fish dishes and raw fish-eating habits are common. Eating and sharing meals together among the community's members, especially relatives and neighbours, are a common practice in both daily life and social gathering events. Fish are a significant protein source and are associated with variety of traditional recipes. Cyprinid fish are one of the most preferred fish by Isaan villagers for daily consumption because they are accessible and affordable. Consumption of these fish probably causes the persistence of high endemicity of human liver fluke infection, particularly with Opisthorchis viverrini, in northeast Thailand. Because the consumption of raw cyprinid fish is a well-documented risk factor for liver fluke infection, sharing of risky raw fish dishes may influence disease transmission through a community. Social network analysis was used to investigate fish and fish-based meal sharing among household members in Isaan villages in liver fluke endemic areas. The findings from three studies confirmed the persistence of traditional Isaan raw fish consumption and food-sharing practice. Social connections via food sharing among villagers played an important role in liver fluke infection and transmission dynamics as a risk factor. Thus these sociocultural factors should be taken into account in designing strategies for control of opisthorchiasis and other food-borne illnesses at the community level.

Trends of child undernutrition in rural Ecuadorian communities with differential access to roads, 2004-2013

Road access can influence protective and risk factors associated with nutrition by affecting various social and biological processes. In northern coastal Ecuador, the construction of new roads created a remoteness gradient among villages, providing a unique opportunity to examine the impact of roads on child nutritional outcomes 10 years after the road was built. Anthropometric and haemoglobin measurements were collected from 2,350 children <5 years in Esmeraldas, Ecuador, from 2004 to 2013 across 28 villages with differing road access. Logistic generalized estimating equation models assessed the longitudinal association between village remoteness and prevalence of stunting, wasting, underweight, overweight, obesity, and anaemia. We examined the influence of socio-economic characteristics on the pathway between remoteness and nutrition by comparing model results with and without household-level socio-economic covariates. Remoteness was associated with stunting (OR = 0.43, 95% CI [0.30, 0.63]) and anaemia (OR = 0.56, 95% CI [0.44, 0.70]). Over time, the prevalence of stunting was generally decreasing but remained higher in villages closer to the road compared to those farther away. Obesity increased (0.5% to 3%) over time; wasting was high (6%) but stable during the study period. Wealth and education partially explained the better nutritional outcomes in remote vs. road villages more than a decade after some communities gained road access. Establishing the extent to which these patterns persist requires additional years of observation.

Material wealth in 3D: Mapping multiple paths to prosperity in low- and middle- income countries

Material wealth is a key factor shaping human development and well-being. Every year, hundreds of studies in social science and policy fields assess material wealth in low- and middle-income countries assuming that there is a single dimension by which households can move from poverty to prosperity. However, a one-dimensional model may miss important kinds of prosperity, particularly in countries where traditional subsistence-based livelihoods coexist with modern cash economies. Using multiple correspondence analysis to analyze representative household data from six countries-Nepal, Bangladesh, Ethiopia, Kenya, Tanzania and Guatemala-across three world regions, we identify a number of independent dimension of wealth, each with a clear link to locally relevant pathways to success in cash and agricultural economies. In all cases, the first dimension identified by this approach replicates standard one-dimensional estimates and captures success in cash economies. The novel dimensions we identify reflect success in different agricultural sectors and are independently associated with key benchmarks of food security and human growth, such as adult body mass index and child height. The multidimensional models of wealth we describe here provide new opportunities for examining the causes and consequences of wealth inequality that go beyond success in cash economies, for tracing the emergence of hybrid pathways to prosperity, and for assessing how these different pathways to economic success carry different health risks and social opportunities.

Racial inequality in the annual risk of Tuberculosis infection in the United States, 1910-1933

Tuberculosis (TB) mortality rates in the USA fell rapidly from 1910 to 1933. However, during this period, racial disparities in TB mortality in the nation's expanding cities grew. Because of long delays between infection and disease, TB mortality is a poor indicator of short-term changes in transmission. We estimated the annual risk of TB infection (ARTI) in 11 large US cities to understand whether rising inequality in mortality reflected rising inequality in ARTI using city-level TB mortality data compiled by the US Department of Commerce from 1910 to 1933. We estimated ARTI for African-Americans and whites using pediatric extrapulmonary TB mortality data for African-Americans and whites in our panel of cities. We also estimated age-adjusted pulmonary TB mortality rates for these cities. We find that the ratio of ARTI for African-Americans vs. whites increased from 2·1 (95% CI = 1·7, 2·4) in 1910 to 4·2 (95% CI = 3·4, 5·2) in 1933. This change mirrored the increasing inequality in age-adjusted pulmonary TB mortality during this period. These findings may reflect the combined effects of migration, inequality in access to care, increasing population density, and racial residential segregation in northern cities during this period.

Exposure-response relationship of neighbourhood sanitation and children's diarrhoea

OBJECTIVES

To assess the association of neighbourhood sanitation coverage with under-five children's diarrhoeal morbidity and to evaluate its exposure-response relationship.

METHODS

We used the Demographic and Health Surveys (DHS) of 29 developing countries in sub-Saharan Africa and South Asia, conducted between 2010 and 2014. The primary outcome was two-week incidence of diarrhoea in children under 5 years of age (N = 269014). We conducted three-level logistic regression analyses and applied cubic splines to assess the trend between neighbourhood-level coverage of improved household sanitation and diarrhoeal morbidity.

RESULTS

A significant association between neighbourhood-level coverage of improved household sanitation and diarrhoeal morbidity (OR [95% CI] = 0.68 [0.62-0.76]) was found. Exposure-relationship analyses results showed improved sanitation coverage threshold at 0.6. We found marginal degree of association (OR [95% CI] = 0.82 [0.77-0.87]) below the threshold, which, beyond the threshold, sharply increased to OR of 0.44 (95% CI: 0.29-0.67) at sanitation coverage of 1 (i.e. neighbourhood-wide use of improved household sanitation). Similar exposure-response trends were identified for urban and rural subgroups.

CONCLUSIONS

Our findings suggest that neighbourhood sanitation plays a key role in reducing diarrhoeal diseases and that increase in sanitation coverage may only have minimal impact on diarrhoeal illness, unless sufficiently high coverage is achieved.

Social network analysis of food sharing among households in opisthorchiasis endemic villages of Lawa Lake, Thailand

Consumption of raw fish is a well-documented risk factor for Opisthorchis viverrini infection. Sharing of food, especially raw fish recipes may influence the spread of disease through a community. Using social network analysis of an ego network, we investigated food sharing among households in an Opisthorchis-endemic area. Network centrality properties were used to explain the differences in O. viverrini transmission and control between villages with a low and high prevalence of infection. Information on demography and O. viverrini infection in 2008 from villagers in the Lawa Lake area was extracted from the Tropical Disease Research Center database. The two villages that had the lowest and the highest O. viverrini infection at the household level were recruited. Ten percent of households of each village were randomly sampled. Participatory epidemiology and face-to-face structured interviews guided by a social network questionnaire were used to collect data on livelihood, agricultural patterns, food sources, raw fish eating habits, and other food sharing during daily life and social gatherings. The number of contacts including in-degree and out-degree varied from 0 to 7 in the low-infection village and 0 to 4 in the high-infection village. The mean number of contacts for the food-sharing network among the low- and high-infection villages was 1.64 and 0.73 contacts per household, respectively. Between these villages, the mean number of out-degree (p=0.0125), but not in-degree (p=0.065), was significantly different. Food-sharing differed in numbers of sharing-in and sharing-out between the two villages. Network analysis of food sharing may be of value in designing strategies for opisthorchiasis control at the community level.

Dueling biological and social contagions

Numerous models explore how a wide variety of biological and social phenomena spread in social networks. However, these models implicitly assume that the spread of one phenomenon is not affected by the spread of another. Here, we develop a model of “dueling contagions”, with a particular illustration of a situation where one is biological (influenza) and the other is social (flu vaccination). We apply the model to unique time series data collected during the 2009 H1N1 epidemic that includes information about vaccination, flu, and face-to-face social networks. The results show that well-connected individuals are more likely to get vaccinated, as are people who are exposed to friends who get vaccinated or are exposed to friends who get the flu. Our dueling contagion model suggests that other epidemiological models may be dramatically underestimating the R₀ of contagions. It also suggests that the rate of vaccination contagion may be even more important than the biological contagion in determining the course of the disease. These results suggest that real world and online platforms that make it easier to see when friends have been vaccinated (personalized vaccination campaigns) and when they get the flu (personalized flu warnings) could have a large impact on reducing the severity of epidemics. They also suggest possible benefits from understanding the coevolution of many kinds of dueling contagions.

Differential effects of stress and African ancestry on preterm birth and related traits among US born and immigrant Black mothers

Preterm birth (PTB, <37 weeks of gestation) is influenced by a wide range of environmental, genetic and psychosocial factors, and their interactions. However, the individual and joint effects of genetic factors and psychosocial stress on PTB have remained largely unexplored among U.S. born versus immigrant mothers.We studied 1121 African American women from the Boston Birth Cohort enrolled from 1998 to 2008. Regression-based analyses were performed to examine the individual and joint effects of genetic ancestry and stress (including lifetime stress [LS] and stress during pregnancy [PS]) on PTB and related traits among U.S. born and immigrant mothers.Significant associations between LS and PTB and related traits were found in the total study population and in immigrant mothers, including gestational age, birthweight, PTB, and spontaneous PTB; but no association was found in U.S. born mothers. Furthermore, significant joint associations of LS (or PS) and African ancestral proportion (AAP) on PTB were found in immigrant mothers, but not in U.S. born mothers.Although, overall, immigrant women had lower rates of PTB compared to U.S. born women, our study is one of the first to identify a subset of immigrant women could be at significantly increased risk of PTB and related outcomes if they have high AAP and are under high LS or PS. In light of the growing number of immigrant mothers in the U.S., our findings may have important clinical and public health implications.

Public health impacts of ecosystem change in the Brazilian Amazon

The claim that nature delivers health benefits rests on a thin empirical evidence base. Even less evidence exists on how specific conservation policies affect multiple health outcomes. We address these gaps in knowledge by combining municipal-level panel data on diseases, public health services, climatic factors, demographics, conservation policies, and other drivers of land-use change in the Brazilian Amazon. To fully exploit this dataset, we estimate random-effects and quantile regression models of disease incidence. We find that malaria, acute respiratory infection (ARI), and diarrhea incidence are significantly and negatively correlated with the area under strict environmental protection. Results vary by disease for other types of protected areas (PAs), roads, and mining. The relationships between diseases and land-use change drivers also vary by quantile of the disease distribution. Conservation scenarios based on estimated regression results suggest that malaria, ARI, and diarrhea incidence would be reduced by expanding strict PAs, and malaria could be further reduced by restricting roads and mining. Although these relationships are complex, we conclude that interventions to preserve natural capital can deliver cobenefits by also increasing human (health) capital.

Inferring a district-based hierarchical structure of social contacts from census data

Researchers have recently paid attention to social contact patterns among individuals due to their useful applications in such areas as epidemic evaluation and control, public health decisions, chronic disease research and social network research. Although some studies have estimated social contact patterns from social networks and surveys, few have considered how to infer the hierarchical structure of social contacts directly from census data. In this paper, we focus on inferring an individual’s social contact patterns from detailed census data, and generate various types of social contact patterns such as hierarchical-district-structure-based, cross-district and age-district-based patterns. We evaluate newly generated contact patterns derived from detailed 2011 Hong Kong census data by incorporating them into a model and simulation of the 2009 Hong Kong H1N1 epidemic. We then compare the newly generated social contact patterns with the mixing patterns that are often used in the literature, and draw the following conclusions. First, the generation of social contact patterns based on a hierarchical district structure allows for simulations at different district levels. Second, the newly generated social contact patterns reflect individuals social contacts. Third, the newly generated social contact patterns improve the accuracy of the SEIR-based epidemic model.

Social networks and health: a systematic review of sociocentric network studies in low- and middle-income countries

In low- and middle-income countries (LMICs), naturally occurring social networks may be particularly vital to health outcomes as extended webs of social ties often are the principal source of various resources. Understanding how social network structure, and influential individuals within the network, may amplify the effects of interventions in LMICs, by creating, for example, cascade effects to non-targeted participants, presents an opportunity to improve the efficiency and effectiveness of public health interventions in such settings. We conducted a systematic review of PubMed, Econlit, Sociological Abstracts, and PsycINFO to identify a sample of 17 sociocentric network papers (arising from 10 studies) that specifically examined health issues in LMICs. We also separately selected to review 19 sociocentric network papers (arising from 10 other studies) on development topics related to wellbeing in LMICs. First, to provide a methodological resource, we discuss the sociocentric network study designs employed in the selected papers, and then provide a catalog of 105 name generator questions used to measure social ties across all the LMIC network papers (including both ego- and sociocentric network papers) cited in this review. Second, we show that network composition, individual network centrality, and network structure are associated with important health behaviors and health and development outcomes in different contexts across multiple levels of analysis and across distinct network types. Lastly, we highlight the opportunities for health researchers and practitioners in LMICs to 1) design effective studies and interventions in LMICs that account for the sociocentric network positions of certain individuals and overall network structure, 2) measure the spread of outcomes or intervention externalities, and 3) enhance the effectiveness and efficiency of aid based on knowledge of social structure. In summary, human health and wellbeing are connected through complex webs of dynamic social relationships. Harnessing such information may be especially important in contexts where resources are limited and people depend on their direct and indirect connections for support.

Ask when--not just whether--it's a risk: How regional context influences local causes of diarrheal disease

Contemporary epidemiology is enriched when it incorporates ecological concepts about systems and dependencies. With regard to diarrheal disease, the causes of which are many and interacting, the dynamics of within- and between-community disease transmission have distinct components but are also linked in important ways. However, few investigators have studied how regional-scale disease dynamics affect local patterns of diarrheal disease transmission. Characterizing this dependence is important for identifying local- and regional-level transmission pathways. We used data from active surveillance of diarrheal disease prevalence gathered from February 2004 through July 2007 in 21 neighboring Ecuadorian villages to estimate how disease prevalence in spatially and temporally proximate villages modulates the influences of village-level risk and protective factors. We found that the impact of local, village-level interventions such as improved latrines and water treatment can be quite different under conditions of high and low regional disease prevalence. In particular, water treatment was effective only when regional disease prevalence was low, suggesting that person-to-person spread, not waterborne spread, is probably responsible for most between-village transmission in this region. Additional regional-scale data could enhance our understanding of how regional-scale transmission affects local-scale dynamics.

Heavy rainfall events and diarrhea incidence: the role of social and environmental factors

The impact of heavy rainfall events on waterborne diarrheal diseases is uncertain. We conducted weekly, active surveillance for diarrhea in 19 villages in Ecuador from February 2004 to April 2007 in order to evaluate whether biophysical and social factors modify vulnerability to heavy rainfall events. A heavy rainfall event was defined as 24-hour rainfall exceeding the 90th percentile value (56 mm) in a given 7-day period within the study period. Mixed-effects Poisson regression was used to test the hypothesis that rainfall in the prior 8 weeks, water and sanitation conditions, and social cohesion modified the relationship between heavy rainfall events and diarrhea incidence. Heavy rainfall events were associated with increased diarrhea incidence following dry periods (incidence rate ratio = 1.39, 95% confidence interval: 1.03, 1.87) and decreased diarrhea incidence following wet periods (incidence rate ratio = 0.74, 95% confidence interval: 0.59, 0.92). Drinking water treatment reduced the deleterious impacts of heavy rainfall events following dry periods. Sanitation, hygiene, and social cohesion did not modify the relationship between heavy rainfall events and diarrhea. Heavy rainfall events appear to affect diarrhea incidence through contamination of drinking water, and they present the greatest health risks following periods of low rainfall. Interventions designed to increase drinking water treatment may reduce climate vulnerability.