Estimating the burden of disease from water,sanitation, and hygiene at a global level

We estimated the disease burden from water, sanitation, and hygiene at the global level taking into account various disease outcomes, principally diarrheal diseases. The disability-adjusted life year (DALY) combines the burden from death and disability in a single index and permits the comparison of the burden from water, sanitation, and hygiene with the burden from other risk factors or diseases. We divided the world's population into typical exposure scenarios for 14 geographical regions. We then matched these scenarios with relative risk information obtained mainly from intervention studies. We estimated the disease burden from water, sanitation, and hygiene to be 4.0% of all deaths and 5.7% of the total disease burden (in DALYs) occurring worldwide, taking into account diarrheal diseases, schistosomiasis, trachoma, ascariasis, trichuriasis, and hookworm disease. Because we based these estimates mainly on intervention studies, this burden is largely preventable. Other water- and sanitation-related diseases remain to be evaluated. This preliminary estimation of the global disease burden caused by water, sanitation, and hygiene provides a basic model that could be further refined for national or regional assessments. This significant and avoidable burden suggests that it should be a priority for public health policy.     

Interventions for the control of diarrhoeal diseases among young children: improving water supplies and excreta disposal facilities

A theoretical model is proposed that relates the level of ingestion of diarrhoea-causing pathogens to the frequency of diarrhoea in the community. The implications of this model are that, in poor communities with inadequate water supply and excreta disposal, reducing the level of enteric pathogen ingestion by a given amount will have a greater impact on diarrhoea mortality rates than on morbidity rates, a greater impact on the incidence rate of severe diarrhoea than on that of mild diarrhoea, and a greater impact on diarrhoea caused by pathogens having high infectious doses than on diarrhoea caused by pathogens of a low infectious dose. The impact of water supply and sanitation on diarrhoea, related infections, nutritional status, and mortality is analysed by reviewing 67 studies from 28 countries. The median reductions in diarrhoea morbidity rates are 22% from all studies and 27% from a few better-designed studies. All studies of the impact on total mortality rates show a median reduction of 21%, while the few better-designed studies give a median reduction of 30%. Improvements in water quality have less of an impact than improvements in water availability or excreta disposal.     

The associations between feeding modes and diarrhoea among urban children in a newly developed country

The protective effect of breastfeeding against infantile diarrhoea may be less pronounced in areas with modern water supply and sanitation facilities. This finding raises the question whether protection by breastfeeding against infantile diarrhoea in developing countries will decline with improvement in water supply and sanitation. To address this question a historical cohort study of the associations between feeding modes and diarrhoea incidence and severity in children aged 0–14 months at baseline was done in Al Ain city, United Arab Emirates. In this city in a newly developed country, modern water supply and sanitation facilities have become available to everyone during the last two decades. During three months of follow-up of 249 children, the nonbreastfed had more diarrhoea than did the partly breastfed, who in turn had more diarrhoea than did the fully breastfed. After multivariate adjustment, this dose-response effect was consistent for three measures of diarrhoeal morbidity in each child: occurrence or non-occurrence of incidence episodes, number of episodes, and total severity score. However, significant differences were seen only between the nonbreastfed and fully breastfed subgroups. These results indicate that in Al Ain, despite the universal access to modern water supply and sanitation facilities, breastfeeding plays an important role in reducing the incidence and severity of infantile diarrhoea. This observation is particularly important given the growing concern that, as an unwanted effect of ‘modernisation’, breastfeeding is on the decline in Al Ain and comparable populations elsewhere.     

De-worming school children and hygiene intervention

Helminths or worm infestations refer to worms that live as parasites in the human body and are a fundamental cause of disease associated with health and nutrition problems beyond gastrointestinal tract disturbances. Globally, over 3.5 billion people are infected with intestinal worms, of which 1.47 billion are with roundworm, 1.3 billion people with hookworm and 1.05 billion with whipworm. School children aged 5 - 15 years suffer the highest infection rate and worm burden that attributes to poor sanitation and hygiene. About 400 million school-age children are infected with roundworm, whipworm and hookworm worldwide, a large proportion of whom are found in the East Asia region (Cambodia, China, Lao PDR, Thailand and Vietnam). These parasites consume nutrients from children they infect, thus retarding their physical development. They destroy tissues and organs, cause abdominal pain, diarrhoea, intestinal obstruction, anaemia, ulcers and other health problems. All of these consequences of infection can slow cognitive development and thus impair learning. De-worming school children by anthelmintic drug treatment is a curative approach for expelling the heavy worm load. However, drug therapy alone is only a short-term measure of reducing worm infection and re-infection is frequent. Control measures through improved sanitation, hygiene and de-worming are needed to prevent infection and re-infection. UNICEF has supported many governments in this (and other) regions to assist in the provision of water supply and sanitary facilities and intensive hygiene education in many schools through the Water, Environment and Sanitation (WES) programme. The UNICEF supported school sanitation and hygiene education (SSHE) programme, and other programmes, could effectively enhance behaviour change in children to break the routes of worm transmission and other waterborne diseases.     

Effect of water supply and sanitation on the prevalence and intensity of Ascaris lumbricoides among pre-school-age children in Ajebandele and Ifewara,Osun State,Nigeria

The relationship between Ascaris lumbricoides infection and provisions for safe water supply and excreta disposal was investigated in Ajebandele and Ifewara, 2 peri-urban communities near Ile-Ife, Osun State, Nigeria, from September 1998 to December 1999. Although there were more facilities for safe water supply (pipe-borne and shallow wells) and sanitation (flush toilets and pit latrines) in Ajebandele than in Ifewara, they were not evenly distributed and only a few families, mainly in Ajebandele, were well provided for. Our results indicated that the prevalence of A. lumbricoides was significantly higher in Ifewara (21.2%) than in Ajebandele (13.1%), and within villages was much lower in houses with tap water and flush toilets. However, the mean intensity of infection was unexpectedly higher in Ajebandele (166.5 +/- 692.0) than in Ifewara (153.1 +/- 485.8) suggesting that the present level of investment in Ajebandele is probably not sufficient to reduce morbidity. These findings confirm suggestions that there is a threshold level of investment below which interventions on water supply and sanitation may not significantly improve human health. Sustainable ascariasis control in the study communities will require significant improvements to existing water supplies and sanitation facilities and any future interventions should incorporate a programme of health education to ensure that the facilities provided are properly used and hygienically maintained.     

Burden of disease from inadequate water,sanitation and hygiene for selected adverse health outcomes: An updated analysis with a focus on low- and middle-income countries

BackgroundTo develop updated estimates in response to new exposure and exposure-response data of the burden of diarrhoea, respiratory infections, malnutrition, schistosomiasis, malaria, soil-transmitted helminth infections and trachoma from exposure to inadequate drinking-water, sanitation and hygiene behaviours (WASH) with a focus on low- and middle-income countries.MethodsFor each of the analysed diseases, exposure levels with both sufficient global exposure data for 2016 and a matching exposure-response relationship were combined into population-attributable fractions. Attributable deaths and disability-adjusted life years (DALYs) were estimated for each disease and, for most of the diseases, by country, age and sex group separately for inadequate water, sanitation and hygiene behaviours and for the cluster of risk factors. Uncertainty estimates were computed on the basis of uncertainty surrounding exposure estimates and relative risks.FindingsAn estimated 829,000 WASH-attributable deaths and 49.8 million DALYs occurred from diarrhoeal diseases in 2016, equivalent to 60% of all diarrhoeal deaths. In children under 5 years, 297,000 WASH-attributable diarrhoea deaths occurred, representing 5.3% of all deaths in this age group. If the global disease burden from different diseases and several counterfactual exposure distributions was combined it would amount to 1.6 million deaths, representing 2.8% of all deaths, and 104.6 million DALYs in 2016.ConclusionsDespite recent declines in attributable mortality, inadequate WASH remains an important determinant of global disease burden, especially among young children. These estimates contribute to global monitoring such as for the Sustainable Development Goal indicator on mortality from inadequate WASH.     

Reduction in diarrhoeal diseases in children in rural Bangladesh by environmental and behavioural modifications

The impact of a water, sanitation and hygiene education intervention project on diarrhoeal morbidity in children under 5 years old was evaluated in a rural area of Bangladesh. Data were collected throughout 1984-1987, covering both pre- and post-intervention periods, from an intervention and a control area. The 2 areas were similar with respect to most socio-economic characteristics and baseline levels of diarrhoeal morbidity. The project showed a striking impact on the incidence of all cases of diarrhoea, including dysentery and persistent diarrhoea. By the end of the study period, children in the intervention area were experiencing 25% fewer episodes of diarrhoea than those in the control area. This impact was evident throughout the year, but particularly in the monsoon season, and in all age groups except those less than 6 months old. Within the intervention area, children from households living closer to handpumps or where better sanitation habits were practised experienced lower rates of diarrhoea. These results suggest that an integrated approach to environmental interventions can have a significant impact on diarrhoeal morbidity.     

The Imo State (Nigeria) Drinking Water Supply and Sanitation Project, 2. Impact on dracunculiasis, diarrhoea and nutritional status

Morbidity due to dracunculiasis (guinea worm disease) and diarrhoea in persons of all ages, and nutritional status of young children, were used as health impact indicators in the evaluation of the Imo State Drinking Water Supply and Sanitation Project in south-eastern Nigeria. Data were collected using repeated cross-sectional surveys and longitudinal follow-up. The study area was found to have a low level of endemicity of dracunculiasis. While no impact could be demonstrated on overall period or point prevalence rates in the cross-sectional surveys, a prospective longitudinal survey showed a significant reduction in the percentage of person-fortnights positive for dracunculiasis in areas served by the project, while the control areas showed no such change. In the cross-sectional surveys it was found that, in the project villages, those persons drinking only borehole water had significantly lower period prevalence rates one year later than others. Moreover, those living further from the nearest borehole had higher rates of dracunculiasis. An impact of the project on diarrhoea morbidity was found only in limited sub-groups of the population. A greater association with water availability rather than quality was suggested for rates in young children. The prevalence of wasting (less than 80% weight-for-height) among children aged less than 3 years decreased significantly over time in all 3 intervention villages; there was no such decline in the control villages.     

Equity implications for sanitation from recent health and nutrition evidence

Recent evidence points to the possible underestimation of the health and nutrition impact of sanitation. Community sanitation coverage may first need to reach thresholds in the order of 60% or higher, to optimize health and nutrition gains. Increasing coverage of sanitation to levels below 60% of community coverage may not result in substantial gains. For example, moving Indonesia from 60% to 100% improved sanitation coverage could significantly reduce diarrhoea in children under 5 years old (by an estimated 24% reduction in odds ratio for child diarrhoea morbidity) with gains split equally by reaching underserved communities and the unserved within communities. We review the implications of these results across three levels of program implementation – from micro level approaches (that support communities to achieve open defecation-free status), to meso level (sub-national implementation) to macro level approaches for the national enabling environment and the global push to the Sustainable Development Goals. We found significant equity implications and recommend that future studies focus more extensively on community coverage levels and verified community open defecation free status rather than household access alone. Sanitation practitioners may consider developing phased approaches to improving water, sanitation and hygiene in communities while prioritizing the unserved or underserved.     

Clean water,sanitation and diarrhoea in Indonesia: Effects of household and community factors

Diarrhoea is an important health issue in low- and middle-income countries, including Indonesia. We applied a multilevel regression analysis on the Indonesian Demographic and Health Survey to examine the effects of drinking water and sanitation facilities at the household and community level on diarrhoea prevalence among children under five (n?=?33,339). The role of the circumstances was explored by studying interactions between the water and sanitation variables and other risk factors. Diarrhoea prevalence was reported by 4820 (14.4%) children, who on average were younger, poorer and were living in a poorer environment. At the household level, piped water was significantly associated with diarrhoea prevalence (OR?=?0.797, 95% CI: 0.692–0.918), improved sanitation had no direct effect (OR?=?0.992, 95% CI: 0.899–1.096) and water treatment was not related to diarrhoea incidence (OR?=?1.106, 95% CI: 0.994–1.232). At the community level, improved water coverage had no direct effect (OR?=?1.002, 95% CI: 0.950–1.057) but improved sanitation coverage was associated with lower diarrhoea prevalence (OR?=?0.917, 95% CI: 0.843–0.998). Our interaction analysis showed that the protective effects of better sanitation at the community level were increased by better drinking water at the community level. This illustrates the importance of improving both drinking water and sanitation simultaneously.     

Low risk for helminth infection in wastewater-fed rice cultivation in Vietnam

This study was done to assess the risk of helminth infection in association with wastewater-fed rice cultivation in an agricultural setting of Nam Dinh city, Vietnam. In a cross sectional survey data were collected for 202 households in a commune where wastewater was used for irrigation and for 201 households in a commune that used river water. Parasitological examination was conducted on single stool samples obtained from 1,088 individuals aged -15 years from the households. The irrigation water used in both communes was enumerated for helminth eggs and thermotolerant coliforms. The prevalence of infection with Ascaris spp., Trichuris spp., and hookworm was 42.2%, 19.9% and 10.5% respectively, with an overall prevalence of infection with any helminth of 53.4%. Surprisingly, the prevalence of infection with Ascaris and Trichuris was lower among people exposed to wastewater (containing 40-200 helminth eggs/l and 10(4) thermotolerant coliforms/100 ml) compared to people exposed to river water that contained lower worm egg and bacterial numbers. Poor sanitation and hygiene practices and not using protective measures were important independent risk factors for helminth infection. For hookworm infection, no significant difference was observed between the wastewater exposed and unexposed groups. Children living in the wastewater use area had a significantly better nutritional status than those in the area using river water. This suggests a generally higher welfare level of the wastewater use area. In conclusion, this study showed no evidence that rice cultivation with wastewater poses a risk for helminth infection. More detailed studies are needed on the reduction of fecal indicators and helminth eggs in peri-urban wastewater-irrigated rice culture systems and on the relative importance of wastewater irrigation compared to other risk factors for human helminth infection such as poor sanitation and poverty.     

Water supply, sanitation and diarrhoeal disease in Nicaragua: results from a case-control study

A case-control study of risk factors for child diarrhoeal disease was undertaken in a rural area of Nicaragua. Some 1229 children under the age of five were matched with an equal number of children of the same age presenting with other illnesses unrelated to water and sanitation. The main types of water supply were sampled at monthly intervals and tested for the presence of faecal coliforms in order to characterize their microbiological quality. In spite of marked differences in water quality between the different types of water supply, no relationship was found with diarrhoea morbidity. In contrast, there was a statistically significant association between water availability and diarrhoea morbidity. Children from homes with water supplies over 500 meters from the house had incidence rates of diarrhoea 34% higher than those of children from houses with their own water supply. Owning a latrine was not found to be significantly related to diarrhoea morbidity. A mother's level of schooling was inversely correlated with the frequency of diarrhoea in her children. A significant association was also found between the number of children under the age of five living in the house and the incidence of diarrhoea. These effects remained significant after controlling for confounding variables by conditional logistic regression.     

Sanitation, community environments, and childhood diarrhoea in rural Zimbabwe

Childhood diarrhoea can be transmitted within the household and community environments. This study examined the effect of partial latrine coverage on diarrhoeal morbidity at the household and community levels. Weekly morbidity data on 272 children, aged less than five years, were collected for 45 weeks from October 1996 to August 1997 in two neighbouring semi-arid communities in rural Zimbabwe. The communities were similar except for sanitation. In Community A, 62% of the children lived in households with a latrine, and in Community B, there was no sanitation. Diarrhoeal morbidity was 68% lower in Community A than in Community B. In addition, the children from the households in Community A without a latrine had lower diarrhoeal morbidity than the children in Community B. The inter-community difference in diarrhoeal morbidity was likely to be due to the latrines and associated hygiene education interrupting intra- and inter-household transmission of diarrhoea. The latrines reduced faecal contamination of the community environment, and as diarrhoeal morbidity fell, contact between infectives and susceptibles within the community would also have fallen. The neighbourhoods in Community A where the adjacent households did not have sanitation had higher diarrhoeal morbidity than in the neighbourhoods where one household did have sanitation. The results of the study suggest that sanitation programmes, which share building costs between the state and individuals, i.e. households, and hence, do not achieve complete coverage in a community, benefit the whole community, because the households that cannot afford a latrine experience lower diarrhoeal morbidity due to the safer community environment.     

Effects of Hygiene and Sanitation Interventions on Reducing Diarrhoea Prevalence Among Children in Resource Constrained Communities: Case Study of Turkana District, Kenya

Worldwide, lack of access to safe drinking water together with inadequate sanitation and hygiene is an overwhelming contributor to approximately 4 billion cases of illness annually. This study was set out to understand the effects of hygiene and sanitation interventions on targeted health outcomes including diarrhoeal prevalence in children’s of Turkana District, Kenya. The interventions undertaken included capacity building and empowerment approach to trigger communities to demand hygiene and sanitation facilities. Three hundred mothers were randomly sampled in a baseline survey carried out in 2007 and in a post-intervention survey carried out in 2008 (a repeat cross-sectional study design). Specimens were collected for microbiological tests of key diarrhoea related pathogens. Overall, Faecal coliform counts per 100?ml sample had significant variations between 2007 and 2008; in Kakuma, reduced from 88 to 30.2 colony units (P?=?0.005), Lodwar Central where the number reduced from 91 to 17.3 units (P?=?0.003), and in Lokichogio Division, the number reduced from 63.8 to 23.6 units (P?=?0.006). From the 230 stool samples examined, the proportion of children from whom infectious pathogens of Proteus spp. was isolated reduced from 16 to 7?% while Escherichia coli reduced from 54 to 41?%. Overall, prevalence of diarrhoea related microbes in children aged <5?years reduced from 91.3?% in 2007 to 78.3?% after intervention (2008). It is notable that sanitation and hygiene promotion leads to significant reduction of diarrhoea prevalence in children aged <5?years. Its application should therefore be up-scaled in resource constrained areas.     

Lack of impact of a water and sanitation intervention on the nutritional status of children in rural Bangladesh

The nutritional impact of a water and sanitation intervention in a rural community of Bangladesh, comprising the provision of handpumps, construction of latrines and hygiene education was assessed. During 3 years, the quarterly anthropometric measures of about 200 children aged 12-35 months from the intervention community were compared with those of a similar number of children from a control area. The interventions reduced the incidence of diarrhoea by 25 per cent among the children less than 5 years of age. There was no significant difference in nutritional status, however, between the two groups of children. Moreover, within the intervention area, indicators of water and latrine use were not significantly related to the children's nutritional status. This suggests that either the obtained reduction of diarrhoea was not large enough to have an impact on nutritional status or that diarrhoea is not an important cause of malnutrition in this community.     

Clostridium difficile infections related to antibiotic use and infection control facilities in two university hospitals

We investigated whether a reduction in antibiotic use at the Aker University Hospital (Aker) led to a reduction in Clostridium difficile-associated diarrhoea (CDAD). We compared the incidence of CDAD in Aker and Tromsoe University Hospitals (Tromsoe) and related it to antibiotic use and facilities for infection control between 1993-2001. For this purpose we also performed point prevalence studies. Total antibiotic use was the same in the two hospitals. In spite of a reduction in the use of broad-spectrum antibiotics in Aker the incidence of CDAD increased during 1993-1999. In Tromsoe the use of broad-spectrum antibiotics and clindamycin was two to three times higher than in Aker, but until 1999 the incidence of CDAD remained constant and only half that of Aker. After 1999 the incidence of CDAD was halved in Aker, and increased three-fold in Tromsoe. Point prevalence studies in 2001 revealed an equal prevalence of antibiotic-associated diarrhoea. The facilities for infection control were better in Tromsoe. The percentage of single rooms were 8% in Aker and 14% in Tromsoe, and the percentage of single rooms with a WC was 6% in Aker and 12% in Tromsoe. The bed occupancy was much higher in Aker than in Tromsoe. Lack of facilities for infection control and higher bed occupancy could have contributed to the higher incidence of CDAD in Aker in spite of decreased use of broad-spectrum antibiotics and clindamycin. To limit CDAD in hospitals the focus must be on both rational antibiotic use and infection control.     

Incidence and risk factors for diarrhoea and acute respiratory infections in urban communities of Pernambuco, Brazil

Magnitude and distribution of Diarrhoea and Acute Respiratory Infections (ARI) in children were studied within a larger broader research that focused on health education. Two household surveys were conducted in a sample of families with at least one child under five years of Recife and Olinda in April-May 1992 and 1994. The total number of children studied was 5,436. The estimated adjusted annual incidence rate (AAIR) of diarrhoea was 2.7 episodes per child. The two-week incidence rate of diarrhoea was 10.2% for both years. Risk factors associated with higher incidence of diarrhoea were age (under two years), lack of sanitation facilities, and absence of electrical appliances in the household. Estimated AAIR of ARI was 9. 5 episodes per child. The two-week incidence rate of ARI was 41.0% in 1992 and 32.6% in 1994. Majority of ARIs affected the upper respiratory tract (75.9%). The only factor consistently associated with a higher risk of ARI was age (under three years). Study results indicate that both pathologies are still an important health problem for children under five in Pernambuco. In particular, in the case of diarrhoea the need for improving the access to basic services, such as water supply and sewage system is urgently needed.     

The impact of sanitation on infectious disease and nutritional status: A systematic review and meta-analysis

Background

Sanitation aims to sequester human feces and prevent exposure to fecal pathogens. More than 2.4 billion people worldwide lack access to improved sanitation facilities and almost one billion practice open defecation. We undertook systematic reviews and meta-analyses to compile the most recent evidence on the impact of sanitation on diarrhea, soil-transmitted helminth (STH) infections, trachoma, schistosomiasis, and nutritional status assessed using anthropometry.

Health impact of water and sanitation infrastructure reconstruction programmes in eight Central American communities affected by Hurricane Mitch

In response to Hurricane Mitch, which struck Central America in October-November 1998, the American Red Cross (ARC) and the Centers for Disease Control and Prevention (CDC) collaborated on a 3-year evaluation of the public health impact of ARC's water, sanitation and hygiene education activities in eight study areas in Honduras, Nicaragua, El Salvador and Guatemala. The evaluation compared: 1) access to and use of water and sanitation facilities, 2) the use of hygienic behaviours, and 3) diarrhoeal prevalence in children younger than 3 years of age before (February 2000) and after (February 2002) the interventions had been implemented. The evaluation included household and key informant interviews designed to measure these three components. Water quality of community water sources and household water was evaluated by measuring levels of indicator bacteria. During the final survey, an infrastructure evaluation provided a review of the design, construction, and current operation and maintenance of the water systems and latrines. The integrated water and sanitation infrastructure interventions and hygiene education programmes implemented following Hurricane Mitch effectively decreased diarrhoea prevalence in the target communities.