Can open-defecation free (ODF) communities be sustained? A cross-sectional study in rural Ghana.

Community-led total sanitation (CLTS) is a widely used approach to reduce open defecation in rural areas of low-income countries. Following CLTS programs, communities are designated as open defecation free (ODF) when household-level toilet coverage reaches the threshold specified by national guidelines (e.g., 80% in Ghana). However, because sanitation conditions are rarely monitored after communities are declared ODF, the ability of CLTS to generate lasting reductions in open defecation is poorly understood. In this study, we examined the extent to which levels of toilet ownership and use were sustained in 109 communities in rural Northern Ghana up to two and a half years after they had obtained ODF status. We found that the majority of communities (75%) did not meet Ghana's ODF requirements. Over a third of households had either never owned (16%) or no longer owned (24%) a functional toilet, and 25% reported practicing open defecation regularly. Toilet pit and superstructure collapse were the primary causes of reversion to open defecation. Multivariate regression analysis indicated that communities had higher toilet coverage when they were located further from major roads, were not located on rocky soil, reported having a system of fines to punish open defecation, and when less time had elapsed since ODF status achievement. Households were more likely to own a functional toilet if they were larger, wealthier, had a male household head who had not completed primary education, had no children under the age of five, and benefitted from the national Livelihood Empowerment Against Poverty (LEAP) program. Wealthier households were also more likely to use a toilet for defecation and to rebuild their toilet when it collapsed. Our findings suggest that interventions that address toilet collapse and the difficulty of rebuilding, particularly among the poorest and most vulnerable households, will improve the longevity of CLTS-driven sanitation improvements in rural Ghana.

[Epidemic trend and control progress of soil-transmitted nematodiasis in Jiangsu Province].

Soil-transmitted nematodiasis was once widely prevalent in Jiangsu Province, which seriously threatened human health and hindered socioeconomic development. The control efforts over decades resulted in a remarkable decline in the prevalence of soil-transmitted nematode human infections in Jiangsu Province, with a reduction from 59.32% in 1989 to 0.12% in 2019, and the human prevalence remains at < 0.5% since 2013. Since 1987, an integrated strategy has been adopted for the control of soil-transmitted nematodiasis in Jiangsu Province; however, the core interventions varies at different stages, which mainly include deworming, water and sanitation service improvement, health education, and monitoring and assessment. The criteria of effective soil-transmitted nematodiasis control had been achieved in all epidemic counties (districts) of Jiangsu Province by 2019. Further actions to strengthen health education and monitoring and implement precision control measures are required to consolidate the achievements of soil-transmitted nematodiasis control and eliminate the harm of soil-transmitted nematodiasis to humans. This review summarizes the epidemiology, control progress and evolution of control strategy of soil-transmitted nematodiasis in Jiangsu Province.

Changes in historical typhoid transmission across 16 U.S. cities, 1889-1931: Quantifying the impact of investments in water and sewer infrastructures.

Investments in water and sanitation systems are believed to have led to the decline in typhoid fever in developed countries, such that most cases now occur in regions lacking adequate clean water and sanitation. Exploring seasonal and long-term patterns in historical typhoid mortality in the United States can offer deeper understanding of disease drivers. We fit modified Time-series Susceptible-Infectious-Recovered models to city-level weekly mortality counts to estimate seasonal and long-term typhoid transmission. We examined seasonal transmission separately by city and aggregated by water source. Typhoid transmission peaked in late summer/early fall. Seasonality varied by water source, with the greatest variation occurring in cities with reservoirs. We then fit hierarchical regression models to measure associations between long-term transmission and annual financial investments in water and sewer systems. Overall historical $1 per capita ($16.13 in 2017) investments in the water supply were associated with approximately 5% (95% confidence interval: 3-6%) decreases in typhoid transmission, while $1 increases in the overall sewer system investments were associated with estimated 6% (95% confidence interval: 4-9%) decreases. Our findings aid in the understanding of typhoid transmission dynamics and potential impacts of water and sanitation improvements, and can inform cost-effectiveness analyses of interventions to reduce the typhoid burden.

Associating the Change in New COVID-19 Cases to GDP per Capita in 38 European Countries in the First Wave of the Pandemic.

COVID-19 has affected all countries globally. We explore associations between the change in new COVID-19 registered cases per million population and various macroeconomic and well-being indicators in 38 European countries over a 2-month period (1st April-31st May 2020). A statistically significant (p = 0.002) negative association was estimated between the change in new COVID-19 cases and GDP per capita, after controlling for key health determinants including public expenditure on health, life expectancy, smoking tobacco and sanitation. The country with the highest GDP per capita in Europe (i.e., Luxemburg) was found to experience the lowest change in new COVID-19 cases within the time period whilst the opposite was found for countries with lower GDP per capita (i.e., Ukraine, Bulgaria, and Romania). The outcomes of this study indicate that, in the first wave of the pandemic in Europe, a country's GDP per capita might be associated with a lower rate of new COVID-19 cases. The study concludes by suggesting that in European regions a country's economic performance should be a critical health priority for policy makers.

Urban sanitation in Nigeria: the past, current and future status of access, policies and institutions.

Though rated among the largest economies in sub-Saharan Africa, Nigeria is currently grappling with enormous socio-economic challenges such as high poverty rate, power and water supply shortages, large-scale unemployment ratio, economic recession and underperforming agricultural sector. Judging by the scale of urgent political and economic importance, urban sanitation definitely ranks low among the government's priorities. No wonder political slogans and manifestos of political parties feature provision of water supply while sanitation is conspicuously usually omitted. This is suggestive of the opinion that having not critically understood the status, challenges and opportunities associated with sanitation in the country's urban areas might be partly responsible for this. Thus, the current work presents a detailed review of the past, current and future status of urban sanitation in Nigeria in terms of access coverage, policies, institutions and future challenges and opportunities. The past status was difficult to evaluate because of the absence of data and unclear definitions of the term 'sanitation'. The current status shows among other findings that water supply issues receive domineering attention than sanitation, mainly due to merging together of discussions, policies and implementation of the two issues together. In cases where sanitation crops up in the agenda, rural areas are favored more than the urban areas. This pattern is also common in the literature. But the future of urban sanitation in Nigeria is double-edged depending on actions or inactions of the government and other stakeholders. The study further makes recommendations for - balanced and sustainable urban development planning, restructuring of land and housing policies and creation of enabling market environment that could trigger a viable sanitation industry - as the way forward.

[Achievements and prospects on environmental health and sanitary engineering in China].

According to different epochs and development needs, a series of practices on environmental health and sanitary engineering were carried out, which played significant roles in promoting national economic and social developments and protecting the public health. This paper reviewed the main achievements in the past 70 years infields of patriotic health campaign, water sanitation and toilet improvement in rural areas, surveillance and investigation, health standard system, sanitary engineering equipment, stove improvement etc., and then proposed several prospects in the future.

Effects of single and integrated water, sanitation, handwashing, and nutrition interventions on child soil-transmitted helminth and Giardia infections: A cluster-randomized controlled trial in rural Kenya.

BACKGROUND: Helminth and protozoan infections affect more than 1 billion children globally. Improving water quality, sanitation, handwashing, and nutrition could be more sustainable control strategies for parasite infections than mass drug administration, while providing other quality of life benefits. METHODS AND FINDINGS: We enrolled geographic clusters of pregnant women in rural western Kenya into a cluster-randomized controlled trial (ClinicalTrials.gov NCT01704105) that tested 6 interventions: water treatment, improved sanitation, handwashing with soap, combined water treatment, sanitation, and handwashing (WSH), improved nutrition, and combined WSH and nutrition (WSHN). We assessed intervention effects on parasite infections by measuring Ascaris lumbricoides, Trichuris trichiura, hookworm, and Giardia duodenalis among children born to the enrolled pregnant women (index children) and their older siblings. After 2 years of intervention exposure, we collected stool specimens from 9,077 total children aged 2 to 15 years in 622 clusters, including 2,346 children in an active control group (received household visits but no interventions), 1,117 in the water treatment arm, 1,160 in the sanitation arm, 1,141 in the handwashing arm, 1,064 in the WSH arm, 1,072 in the nutrition arm, and 1,177 in the WSHN arm. In the control group, 23% of children were infected with A. lumbricoides, 1% with T. trichiura, 2% with hookworm, and 39% with G. duodenalis. The analysis included 4,928 index children (median age in years: 2) and 4,149 older siblings (median age in years: 5); study households had an average of 5 people, <10% had electricity access, and >90% had dirt floors. Compared to the control group, Ascaris infection prevalence was lower in the water treatment arm (prevalence ratio [PR]: 0.82 [95% CI 0.67, 1.00], p = 0.056), the WSH arm (PR: 0.78 [95% CI 0.63, 0.96], p = 0.021), and the WSHN arm (PR: 0.78 [95% CI 0.64, 0.96], p = 0.017). We did not observe differences in Ascaris infection prevalence between the control group and the arms with the individual interventions sanitation (PR: 0.89 [95% CI 0.73, 1.08], p = 0.228), handwashing (PR: 0.89 [95% CI 0.73, 1.09], p = 0.277), or nutrition (PR: 86 [95% CI 0.71, 1.05], p = 0.148). Integrating nutrition with WSH did not provide additional benefit. Trichuris and hookworm were rarely detected, resulting in imprecise effect estimates. No intervention reduced Giardia. Reanalysis of stool samples by quantitative polymerase chain reaction confirmed the reductions in Ascaris infections measured by microscopy in the WSH and WSHN groups. Trial limitations included imperfect uptake of targeted intervention behaviors, limited power to detect effects on rare parasite infections, and that it was not feasible to blind participants and sample collectors to treatment status. However, lab technicians and data analysts were blinded to treatment status. The trial was funded by the Bill & Melinda Gates Foundation and the United States Agency for International Development. CONCLUSIONS: Integration of improved water quality, sanitation, and handwashing could contribute to sustainable control strategies for Ascaris infections, particularly in similar settings with recent or ongoing deworming programs. Combining nutrition with WSH did not provide further benefits, and water treatment alone was similarly effective to integrated WSH. Our findings provide new evidence that drinking water should be given increased attention as a transmission pathway for Ascaris. TRIAL REGISTRATION: ClinicalTrials.gov NCT01704105.

The use of open source GIS algorithms, big geographic data, and cluster computing techniques to compile a geospatial database that can be used to evaluate upstream bathing and sanitation behaviours on downstream health outcomes in Indonesia, 2000-2008.

BACKGROUND: Waterborne diseases are one of the leading causes of mortality in developing countries, and diarrhea alone is responsible for over 1.5 million deaths annually. Such waterborne illnesses most often affect those in impoverished rural communities who rely on rivers for their supply of drinking water. Deaths are most common among infants and the elderly. Without knowledge of which communities are upstream of a community, upstream sanitary and bathing behaviors can never be directly linked to downstream health outcomes including disease outbreaks. Although current GIS technologies can answer the upstream question for a limited number of downstream communities, no systematic way existed of labeling each downstream village with all its upstream contributing villages along river networks or within basins at the large national scale, such as in Indonesia. This limitation prohibits macro analyses of waterborne illness across developing world communities globally. RESULTS: This novel method approach combines parallel computing, big data, community data, and open source GIS to create a database of upstream communities for 50,000-70,0000 villages in Indonesia across four differing periods. The resultant village database provides information that can be tied to the Indonesian PODES health and behavior surveys in each village to connect upstream sanitary behaviors to downstream health outcomes. We find that the approximately 250,000 communities analyzed across the four periods in Indonesia have a combined total of 13.7 million upstream villages. The average number of upstream villages per village was almost 55, the maximum number of upstream villages for any single village was over 5300. CONCLUSIONS: Advances in big-data availability, particularly high-resolution elevation data, the lowering of the cost of parallel computing options, mass survey data, and open source GIS algorithms that can utilize parallel processing and big-data, open new opportunities for the study of human health at micro granularities but across entire nations. The database generated has already been used by health researchers to compute the influence of upstream behaviors on downstream diarrhea outbreaks and to monitor avoidance behaviors to upstream water behaviors across all downstream 250,000 Indonesian villages over 4 years, and further waterborne health analyses are underway.

Toilet training: what can the cookstove sector learn from improved sanitation promotion?

Within the domain of public health, commonalities exist between the sanitation and cookstove sectors. Despite these commonalities and the grounds established for cross-learning between both sectors, however, there has not been much evidence of knowledge exchange across them to date. Our paper frames this as a missed opportunity for the cookstove sector, given the capacity for user-centred innovation and multi-scale approaches demonstrated in the sanitation sector. The paper highlights points of convergence and divergence in the approaches used in both sectors, with particular focus on behaviour change approaches that go beyond the level of the individual. The analysis highlights the importance of the enabling environment, community-focused approaches and locally specific contextual factors in promoting behavioural change in the sanitation sector. Our paper makes a case for the application of such approaches to cookstove interventions, especially in light of their ability to drive sustained change by matching demand-side motivations with supply-side opportunities. Abbreviation: DALY: Disability-adjusted life year; CHC: Community Health Club; CLTS: Community-Led Total Sanitation; HAP: Household air pollution; BM-WASH: Integrated Behavioural Model for Water, Sanitation and Hygiene; ICS: Improved cookstove; LPG: Liquefied petroleum gas; NBA: Nirmal Bharat Abhiyan; NGO: Non:governmental organisation; OD: Open defecation; ODF: Open defecation free; HAST: Participatory Hygiene and Sanitation Transformation; RANAS: Risks, Attitudes, Norms, Abilities and Self-regulation RCT: Randomised controlled trial; (Sani) FOAM: Focus, Opportunity, Ability and Motivation; SBM: Swachh Bharat Mission; TSC: Total Sanitation Campaign; WASH: Water, Sanitation and Hygiene.

Tailoring Water, Sanitation, and Hygiene (WASH) Targets for Soil-Transmitted Helminthiasis and Schistosomiasis Control.

The World Health Organization's (WHO) 2015-2020 Global Strategy on water, sanitation, and hygiene (WASH) and neglected tropical diseases (NTDs) encourages integration, whilst maintaining existing structured NTD investments, and acceleration towards Sustainable Development Goal (SDG) targets. Accordingly, SDG-associated and WASH-NTD indicators have been developed, commencing important intersectoral dialogue, alongside opportunities for future disease-specific refinements. The rationale for soil-transmitted helminthiasis (STH)- and schistosomiasis-specific WASH considerations, and a traffic-light figure, are presented here to indicate where current international definitions may, or may not, suffice. Certain unique aspects in control dynamics and parasitic lifecycles, however, necessitate additional implementation research with more appropriate measurement indicators developed to record programmatic interventions and to define strategic priorities more effectively.

Enabling Factors for Sustaining Open Defecation-Free Communities in Rural Indonesia: A Cross-Sectional Study.

Community Approaches to Total Sanitation (CATS) programmes, like the Sanitasi Total Berbasis Masyarakat (STBM) programme of the Government of Indonesia, have played a significant role in reducing open defecation though still little is known about the sustainability of the outcomes. We assessed the sustainability of verified Open Defecation Free (ODF) villages and explored the association between slippage occurrence and the strength of social norms through a government conducted cross-sectional data collection in rural Indonesia. The study surveyed 587 households and held focus group discussions (FGDs) in six ODF villages two years after the government's ODF verification. Overall, the slippage rate (i.e., a combination of sub-optimal use of a latrine and open defecation at respondent level) was estimated to be 14.5% (95% CI 11.6-17.3). Results of multivariate logistic regression analyses indicated that (1) weaker social norms, as measured by respondents' perceptions around latrine ownership coverage in their community, (2) a lack of all-year round water access, and (3) wealth levels (i.e., not being in the richest quintile), were found to be significantly associated with slippage occurrence. These findings, together with qualitative analysis, concluded that CATS programmes, including a combination of demand creation, removal of perceived constraints through community support mechanisms, and continued encouragement to pursue higher levels of services with post-ODF follow-up, could stabilize social norms and help to sustain longer-term latrine usage in study communities. Further investigation and at a larger scale, would be important to strengthen these findings.

Sanitation marketing: A systematic review and theoretical critique using the capability approach.

Sanitation is a human right that benefits health. As such, technical and behavioural interventions are widely implemented to increase the number of people using sanitation facilities. These include sanitation marketing interventions (SMIs), in which external support agencies (ESAs) use a hybrid of commercial and social marketing tools to increase supply of, and demand for, sanitation products and services. However, there is little critical discourse on SMIs, or independent rigorous analysis on whether they increase or reduce well-being. Most available information is from ESAs about their own SMI implementation. We systematically reviewed the grey and peer-reviewed literature on sanitation marketing, including qualitatively analysing and calculating descriptive statistics for the parameters measured, or intended to be measured, in publications reporting on 33 SMIs. Guided by the capability approach to development we identified that publications for most SMIs (n = 31, 94%) reported on commodities, whilst fewer reported on parameters related to impacts on well-being (i.e., functionings, n = 22, 67%, and capabilities, n = 20, 61%). When evaluating future SMIs, it may be useful to develop a list of contextualised well-being indicators for the particular SMI's location, taking into account local cultural norms, with this list ideally co-produced with local stakeholders. We identified two common practices in SMIs that can reduce well-being and widen well-being inequalities; namely, the promotion of conspicuous consumption and assaults on dignity, and we discuss the mechanisms by which such impacts occur. We recommend that ESAs understand sanitation marketing's potential to reduce well-being and design SMIs to minimize such detrimental impacts. Throughout the implementation phase ESAs should continuously monitor for well-being impacts and adapt practices to optimise well-being outcomes for all involved.

Trends of improved water and sanitation coverage around the globe between 1990 and 2010: inequality among countries and performance of official development assistance.

BACKGROUND: As the Millennium Development Goals ended, and were replaced by the Sustainable Development Goals, efforts have been made to evaluate the achievements and performance of official development assistance (ODA) in the health sector. In this study, we explore trends in the expansion of water and sanitation coverage in developing countries and the performance of ODA. DESIGN: We explored inequality across developing countries by income level, and investigated how ODA for water and sanitation was committed by country, region, and income level. Changes in inequality were tested via slope changes by investigating the interaction of year and income level with a likelihood ratio test. A random effects model was applied according to the results of the Hausman test. RESULTS: The slope of the linear trend between economic level and sanitation coverage has declined over time. However, a random effects model suggested that the change in slope across years was not significant (e.g. for the slope change between 2000 and 2010: likelihood ratio χ2 = 2.49, probability > χ2 = 0.1146). A similar pro-rich pattern across developing countries and a non-significant change in the slope associated with different economic levels were demonstrated for water coverage. Our analysis shows that the inequality of water and sanitation coverage among countries across the world has not been addressed effectively during the past decade. Our findings demonstrate that the countries with the least coverage persistently received far less ODA per capita than did countries with much more extensive water and sanitation coverage, suggesting that ODA for water and sanitation is poorly targeted. CONCLUSION: The most deprived countries should receive more attention for water and sanitation improvements from the world health community. A strong political commitment to ODA targeting the countries with the least coverage is needed at the global level.

A long way to go - Estimates of combined water, sanitation and hygiene coverage for 25 sub-Saharan African countries.

BACKGROUND: Water, sanitation and hygiene (WASH) are essential for a healthy and dignified life. International targets to reduce inadequate WASH coverage were set under the Millennium Development Goals (MDGs, 1990-2015) and now the Sustainable Development Goals (SDGs, 2016-2030). The MDGs called for halving the proportion of the population without access to adequate water and sanitation, whereas the SDGs call for universal access, require the progressive reduction of inequalities, and include hygiene in addition to water and sanitation. Estimating access to complete WASH coverage provides a baseline for monitoring during the SDG period. Sub-Saharan Africa (SSA) has among the lowest rates of WASH coverage globally. METHODS: The most recent available Demographic Household Survey (DHS) or Multiple Indicator Cluster Survey (MICS) data for 25 countries in SSA were analysed to estimate national and regional coverage for combined water and sanitation (a combined MDG indicator for 'improved' access) and combined water with collection time within 30 minutes plus sanitation and hygiene (a combined SDG indicator for 'basic' access). Coverage rates were estimated separately for urban and rural populations and for wealth quintiles. Frequency ratios and percentage point differences for urban and rural coverage were calculated to give both relative and absolute measures of urban-rural inequality. Wealth inequalities were assessed by visual examination of coverage across wealth quintiles in urban and rural populations and by calculating concentration indices as standard measures of relative wealth related inequality that give an indication of how unevenly a health indicator is distributed across the wealth distribution. RESULTS: Combined MDG coverage in SSA was 20%, and combined basic SDG coverage was 4%; an estimated 921 million people lacked basic SDG coverage. Relative measures of inequality were higher for combined basic SDG coverage than combined MDG coverage, but absolute inequality was lower. Rural combined basic SDG coverage was close to zero in many countries. CONCLUSIONS: Our estimates help to quantify the scale of progress required to achieve universal WASH access in low-income countries, as envisaged under the water and sanitation SDG. Monitoring and reporting changes in the proportion of the national population with access to water, sanitation and hygiene may be useful in focusing WASH policy and investments towards the areas of greatest need.

Improving health in the Arctic region through safe and affordable access to household running water and sewer services: an Arctic Council initiative.

Important health disparities have been documented among the peoples of the Arctic and subarctic, including those related to limited access to in-home improved drinking water and sanitation services. Although improving water, sanitation and hygiene (WASH) has been a focus of the United Nations for decades, the Arctic region has received little attention in this regard. A growing body of evidence highlights inequalities across the region for the availability of in-home drinking WASH services and for health indicators associated with these services. In this review, we highlight relevant data and describe an initiative through the Arctic Council's Sustainable Development Working Group to characterize the extent of WASH services in Arctic nations, the related health indicators and climate-related vulnerabilities to WASH services. With this as a baseline, efforts to build collaborations across the Arctic will be undertaken to promote innovations that can extend the benefits of water and sanitation services to all residents.

Household trends in access to improved water sources and sanitation facilities in Vietnam and associated factors: findings from the Multiple Indicator Cluster Surveys, 2000-2011.

BACKGROUND: Despite progress made by the Millennium Development Goal (MDG) number 7.C, Vietnam still faces challenges with regard to the provision of access to safe drinking water and basic sanitation. OBJECTIVE: This paper describes household trends in access to improved water sources and sanitation facilities separately, and analyses factors associated with access to improved water sources and sanitation facilities in combination. DESIGN: Secondary data from the Vietnam Multiple Indicator Cluster Survey in 2000, 2006, and 2011 were analyzed. Descriptive statistics and tests of significance describe trends over time in access to water and sanitation by location, demographic and socio-economic factors. Binary logistic regressions (2000, 2006, and 2011) describe associations between access to water and sanitation, and geographic, demographic, and socio-economic factors. RESULTS: There have been some outstanding developments in access to improved water sources and sanitation facilities from 2000 to 2011. In 2011, the proportion of households with access to improved water sources and sanitation facilities reached 90% and 77%, respectively, meeting the 2015 MDG targets for safe drinking water and basic sanitation set at 88% and 75%, respectively. However, despite these achievements, in 2011, only 74% of households overall had access to combined improved drinking water and sanitation facilities. There were also stark differences between regions. In 2011, only 47% of households had access to both improved water and sanitation facilities in the Mekong River Delta compared with 94% in the Red River Delta. In 2011, households in urban compared to rural areas were more than twice as likely (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.9-2.5) to have access to improved water and sanitation facilities in combination, and households in the highest compared with the lowest wealth quintile were over 40 times more likely (OR: 42.3; 95% CI: 29.8-60.0). CONCLUSIONS: More efforts are required to increase household access to both improved water and sanitation facilities in the Mekong River Delta, South East and Central Highlands regions of Vietnam. There is also a need to address socio-economic factors associated with inadequate access to improved sanitation facilities.

Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013.

BACKGROUND: The Global Burden of Disease, Injuries, and Risk Factor study 2013 (GBD 2013) is the first of a series of annual updates of the GBD. Risk factor quantification, particularly of modifiable risk factors, can help to identify emerging threats to population health and opportunities for prevention. The GBD 2013 provides a timely opportunity to update the comparative risk assessment with new data for exposure, relative risks, and evidence on the appropriate counterfactual risk distribution. METHODS: Attributable deaths, years of life lost, years lived with disability, and disability-adjusted life-years (DALYs) have been estimated for 79 risks or clusters of risks using the GBD 2010 methods. Risk-outcome pairs meeting explicit evidence criteria were assessed for 188 countries for the period 1990-2013 by age and sex using three inputs: risk exposure, relative risks, and the theoretical minimum risk exposure level (TMREL). Risks are organised into a hierarchy with blocks of behavioural, environmental and occupational, and metabolic risks at the first level of the hierarchy. The next level in the hierarchy includes nine clusters of related risks and two individual risks, with more detail provided at levels 3 and 4 of the hierarchy. Compared with GBD 2010, six new risk factors have been added: handwashing practices, occupational exposure to trichloroethylene, childhood wasting, childhood stunting, unsafe sex, and low glomerular filtration rate. For most risks, data for exposure were synthesised with a Bayesian meta-regression method, DisMod-MR 2.0, or spatial-temporal Gaussian process regression. Relative risks were based on meta-regressions of published cohort and intervention studies. Attributable burden for clusters of risks and all risks combined took into account evidence on the mediation of some risks such as high body-mass index (BMI) through other risks such as high systolic blood pressure and high cholesterol. FINDINGS: All risks combined account for 57·2% (95% uncertainty interval [UI] 55·8-58·5) of deaths and 41·6% (40·1-43·0) of DALYs. Risks quantified account for 87·9% (86·5-89·3) of cardiovascular disease DALYs, ranging to a low of 0% for neonatal disorders and neglected tropical diseases and malaria. In terms of global DALYs in 2013, six risks or clusters of risks each caused more than 5% of DALYs: dietary risks accounting for 11·3 million deaths and 241·4 million DALYs, high systolic blood pressure for 10·4 million deaths and 208·1 million DALYs, child and maternal malnutrition for 1·7 million deaths and 176·9 million DALYs, tobacco smoke for 6·1 million deaths and 143·5 million DALYs, air pollution for 5·5 million deaths and 141·5 million DALYs, and high BMI for 4·4 million deaths and 134·0 million DALYs. Risk factor patterns vary across regions and countries and with time. In sub-Saharan Africa, the leading risk factors are child and maternal malnutrition, unsafe sex, and unsafe water, sanitation, and handwashing. In women, in nearly all countries in the Americas, north Africa, and the Middle East, and in many other high-income countries, high BMI is the leading risk factor, with high systolic blood pressure as the leading risk in most of Central and Eastern Europe and south and east Asia. For men, high systolic blood pressure or tobacco use are the leading risks in nearly all high-income countries, in north Africa and the Middle East, Europe, and Asia. For men and women, unsafe sex is the leading risk in a corridor from Kenya to South Africa. INTERPRETATION: Behavioural, environmental and occupational, and metabolic risks can explain half of global mortality and more than one-third of global DALYs providing many opportunities for prevention. Of the larger risks, the attributable burden of high BMI has increased in the past 23 years. In view of the prominence of behavioural risk factors, behavioural and social science research on interventions for these risks should be strengthened. Many prevention and primary care policy options are available now to act on key risks. FUNDING: Bill & Melinda Gates Foundation.