Sandec: Department of Water and Sanitation in Developing Countries
Sandec Training Tool 1.0 – Module 2 Environmental Health Aspects of Water and Sanitation Summary
Summary The natural and built environment in or chemical contaminants. Microbiologi- which we live, the water we drink, the cal pathogens, present in human excre- air we breathe or the houses we occupy, ta, follow typical transmission routes. greatly affect our health. For instance, if The most relevant pathogens are virus- our drinking water is polluted and con- es (e. g. hepatitis A), bacteria (e. g. chol- tains high numbers of pathogenic micro- era), protozoa (e. g. amoebiasis) or para- organisms, we shall probably suffer from sitic worms (e. g. hookworm). They are bad health. Worldwide, 1.8 million peo- typically transmitted to the new host via ple die every year from diarrhoeal dis- a faecal-oral route, e. g. along the path- Figure 1: Environmental health in the context eases, thereof, 88 % are attributed to un- way of excreta – fingers – food – new of the natural and built environment. safe water supply, inadequate sanitation host. Whether the new host is infect- and hygiene. Moreover, about a third of ed and gets sick or not, is dependent on Not included in Module 2 the population of the developing world is pathogen and host factors (e. g. number Ñ Other environmental health risks aside infected with intestinal worms – in some of transmitted bacteria or health condi- from water and sanitation (e. g. air communities the infection rates are tion of the new host). Certain people are pollution or road safety). even as high as 95 %! Many also suffer at greater infection risk than others (e. g. Ñ Detailed medical aspects of diseases because of chemical contaminants in host factors) if they work in close con- such as: their drinking water: In Bangladesh, tact with faeces, such as pit emptiers or – Pathogen pathways and effects about 30 million people consume water farmers reusing excreta as fertiliser. Fur- inside the human body. with elevated levels of arsenic, which thermore, certain situations cannot only – Disease treatment by pharma- can lead to skin lesions and cancer. increase individual health risk but also ceuticals, disease prevention by In China alone, over 26 million people endanger a whole community: Emer- vaccines. suffer from dental fluorosis due to gency situations, such as flooding, war elevated fluoride in their drinking water. or industrial accidents, are frequently as- Other countries in South Asia and Africa sociated with outbreaks of epidemics. are similarly affected. Of these environ- In contrast to microbial contamination, mental health related diseases, people in chemicals arising in drinking water are developing countries and especially chil- usually of health concern only after ex- dren, carry a disproportionately heavy tended exposure over many years, rather burden. than months. One focus of this module is the health Water treatment and sanitation alone aspect of environmental services, in par- do not efficiently disrupt the transmis- ticular sanitation, water treatment and sion routes of diseases. It is indispensa- Publishing details solid waste management. The global ble that they are accompanied by appro- Publisher: Eawag/Sandec (Department of Water and Sanitation in Developing improvement of these services could priate hygiene practices. Washing hands Countries), P.O. 611, 8600 Dübendorf, contribute significantly to achieving the after defecation or constructing safe Switzerland. Phone +41 (0)44 823 52 86, Millennium Development Goals (MDGs), sanitation facilities are primary barriers, Fax +41 (0)44 823 53 99 especially in reducing child mortali- which prevent pathogens from enter- Editors: Christian Zurbrügg and ty (MDG 4), improving maternal health ing the environment. Washing hands be- Sylvie Peter (MDG 5) and ensuring environmental fore eating or protecting food from flies Concept and Content: Melanie Savi and sustainability (MDG 7). Global improve- are secondary barriers, which prevent Karin Güdel ments in drinking water and sanitation pathogens from infecting a new host or Layout: Melanie Savi and Yvonne Lehnhard services could result in a 25 – 45 % re- contaminating food. To make hygiene Copyright: Eawag/Sandec 2008 duction of diarrhoeal disease morbidity. promotion effective and sustainable, Eawag/Sandec compiled this material, Protecting human health can also lead choices have to be made about which however much of the text and figures are to improving the natural environment: behaviours to target. Too many messag- not Eawag/Sandec property and can be ob- tained from the internet. The modules of Keeping a drinking water source free es may be confusing and counterpro- the Sandec Training Tool are not commer- from chemical, organic and/or micro- ductive. Furthermore, hygiene promo- cial products and may only be reproduced biological contaminants may also im- tion should build on what exists, target freely for non-commercial purposes. The prove the water quality of a nearby lake. a specific audience, identify the motives user must always give credit in citations to Arsenic and fluoride are important ge- for changed behaviour and communicate the original author, source and copyright holder. ogenic contaminants of drinking water positive messages. Hygiene promotion in developing countries, whereas nitrate can thus be highly effective in reducing These lecture notes and matching PowerPoint presentations are available on and lead belong to the most relevant an- water and sanitation-related diseases in the CD of Sandec’s Training Tool. They can thropogenic contaminants. developing countries. be ordered from: [email protected] Water and sanitation-related diseas- Cover photo: Woman washing clothes in es are usually caused by microbiological Napo province, Ecuador. (Source: Melanie Savi)
Sandec Training Tool: Module 2 Content
Content 1 – Definitions & Objectives 4 1.1 What is environmental health? 4 1.2 What is our focus? 5 1.3 What are the environmental health objectives? 6 1.4 Why should the Green Sustainability Agenda also be considered? 7
2 – Introduction 9 2.1 What is the burden of disease? 9 2.2 What is the environmental health impact of water and sanitation? 11 2.3 What is the standardised disease measure? 12 2.4 What are the main causes for water and sanitation-related diseases? 13 2.5 What are the main transmission routes of pathogen-related diseases? 13 2.6 What factors influence occurrence and non-occurrence of infection? 14 2.7 What particular situations can increase the potential and actual risk of disease? 15 2.8 What are the sources of pathogens and places of exposure? 16
3 – Diseases 18 3.1 What is the environmental classification of pathogen-related diseases? 18 3.2 What are the main microbial hazards associated with water and excreta? 19 Ñ Viruses 19 Ñ Bacteria 21 Ñ Protozoa 22 Ñ Helminths (parasitic worms) 23 3.3 What are the main chemical contaminants in drinking water? 25 Ñ Arsenic 25 Ñ Fluoride 26 Ñ Lead 26 Ñ Nitrate 27
4 – Hygiene Approaches 28 4.1 How can we disrupt the transmission routes of pathogens? 28 4.2 Why is hygiene promotion important and what are the challenges of hygiene approaches? 29 4.3 How to make sure that hygiene promotion works? 30 4.4 Why is it important to monitor and evaluate hygiene promotion programmes? 32 4.5 What further aspects of hygiene approaches have to be considered? 33
5 – References and Links 36 Ñ References 36 Ñ Weblinks
Sandec Training Tool: Module 2 1 – Definitions & Objectives
1.1 What is environmental health?
Ñ Environmental health is the branch of public health concerned with the aspects related to the natural and built environment likely to affect human health. Ñ Environmental health also includes the provision of environmental services to households and communities, such as water supply or air pollution control.
The environment in which we live great- Environmental health comprises: ly affects our health. The household, • Sustaining a natural environment free workplace and outdoor environments from undue hazard. can pose a variety of health hazards from • Ensuring a built environment free from contamination of the air we breathe, the undue hazard. water we drink and the food we eat, to • Providing essential environmental the risk of accidental injury from vehi- services to households and communi- cles or unsafe housing. (Cairncross et al., ties. These can include: Figure 2: Contents of environmental health. 2003, p. 7) – Sanitation Environmental health addresses all – Water supply Some facts on environmental health the physical, chemical and biological fac- – Traffic control Worldwide, 13 million deaths could be tors external to a person, and all the – Hygiene promotion prevented every year by making our related factors impacting behaviours. It – Air pollution control environments healthier. encompasses the assessment and con- – Stormwater drainage • Among the children below the age trol of those environmental factors that – Solid waste management of five, one third of all diseases are can potentially affect health. It is target- caused by environmental factors, such ed towards preventing disease and cre- as unsafe water and air pollution. ating health-supportive environments. • An improved environmental manage-
Additional info Ñ McMichael (2003): Climate change and human health – Risks and responses. Geneva, WHO. www.who.int/global- change/publications/cchhbook/en/index. html (last accessed 15.07.08) Ñ WHO/UNICEF (2006): Meeting the MDG drinking water and sanitation target: The urban and rural challenge of the decade. Geneva. www.who.int/water_sanitation_ health/monitoring/jmp2006/en/ (last accessed 15.07.08) Download available on the CD of Sandec’s Photo 1: Dry soil in Mauritania. (Source: Eawag/Sandec) Training Tool and from the Internet.
Sandec Training Tool: Module 2 1 – Definitions & Objectives
1.2 What is our focus?
Ñ Our focus is the environmental health aspect of sanitation, water treatment and storage, hygiene promotion, stormwater drainage, and solid waste management. The module centres on diseases attributable to these aspects, on related disease-causing pathogens and their main transmission routes and on hygiene approaches aiming at reducing the disease burden. The chemical hazards of drinking water are also elucidated.
Air pollution, water quality and the afore- mentioned environmental health factors Risk factor are specifically related to certain dis- eases (cf. Table 2). The most relevant environmental health risk factors com- prise a lack of sanitation and safe water quality, which lead to a large number of Disease or risk diseases. Water, sanitation and hygiene Indoor air pollution Outdoor air pollution Noise Other housing risks Chemicals Recreational environment Water resources management Land use and built environment Other community risks Radiation Occupation Climate change Table 1 reveals that diarrhoeal dis- Lower respiratory eases, intestinal nematode infections, Upper respiratory trachoma, schistosomiasis, lymphatic Diarrhoeal diseases filariasis, and malnutrition are attribut- Malaria able to a fraction of more than 25 % to Intestinal nematode infections the risk factor “water, sanitation and hy- Trachoma giene”. Schistosomiasis
The number of deaths attributable to Chagas disease environmental factors is especially high Lymphatic filariasis in developing countries: The number of Onchocerciasis deaths caused by diarrhoeal diseases in Leishmaniasis 2002 amounted to over 1.5 million in de- Dengue veloping countries, as opposed to less Japanese encephalitis than 20 000 in developed countries. This Sexually transmitted diseases difference (factor 75) is extremely high HIV despite the fact that the population in developing countries is 3.5 times high- Hepatitis B and C er than in industrialised nations. (Prüss- Tuberculosis Üstün et al., 2006, p. 82) Perinatal conditions Hence, provision of safe drinking wa- Congenital anomalies ter and improved sanitation, as well as Malnutrition promotion of good hygiene practices in Cancer developing countries, are the most im- Neuropsychiatric disorders portant interventions to reduce the bur- Cataracts den of these and other diseases. This Deafness module focuses on diseases attribut- Cardiovascular diseases able to water and sanitation, on dis- Chronic obstructive pulmonary ease-causing pathogens and their main disease transmission routes, as well as on hy- Asthma giene approaches aiming at reducing the Musculoskeletal diseases burden of diseases. Detailed medical as- Physical inactivity pects of the diseases, such as pathogen Road traffic accident effects inside the body, disease treat- Falls ment by pharmaceuticals or disease pre- Drowning vention by vaccines are not discussed in Fires this module. Poisonings
Other unintentional injuries Table 1: Indicative values for environmentally attributable fractions classified according to Violence specific environmental risk factors and disease Suicide risks. (Prüss-Üstün et al., 2006, p. 80) Fraction attributable to the environment: : < 5 % : 5 – 25 % : > 25 %
Sandec Training Tool: Module 2 1 – Definitions & Objectives
Risk factors Related diseases Further questions Ñ Can these water-related diseases also Outdoor air pollution Respiratory infections, selected cardiopulmonary be prevented by other means than water diseases, lung cancer and sanitation? Ñ Besides health aspects, what are the Indoor air pollution from solid fuel use Chronic obstructive pulmonary disease, lower other problems caused by inadequate respiratory infections, lung cancer water and sanitation services?
Lead Mild mental retardation, cardiovascular diseases Ñ What is the relation between malnutri- tion, water and sanitation? Water, sanitation and hygiene Diarrhoeal diseases, trachoma, schistosomiasis, Ñ Why is malaria not listed as a water and ascariasis, trichuriasis, hookworm disease sanitation-related disease in Table 1?
Climate change Diarrhoeal diseases, malaria, selected unintentional Additional info injuries, protein-energy malnutrition Ñ Cairncross (2003): Health, environment and the burden of disease; A guidance Selected occupational factors: note. London, DFID. www.dfid.gov.uk/ Injuries Unintentional injuries Pubs/files/healthenvirondiseaseguidenote. Noise Hearing loss pdf (last accessed 15.07.08) Carcinogenics Cancers Ñ Prüss-Üstün (2006): Preventing disease through healthy environments. Towards Airborne particulates Asthma, chronic obstructive pulmonary disease an estimate of the environmental burden Ergonomic stressors Low back pain of disease. Geneva, WHO. www.who.int/ quantifying_ehimpacts/publications/pre- Table 2: Diseases related to different risk factors. (Prüss-Üstün et al., 2006, p. 27) ventingdisease/en/index.html (last accessed 15.07.08) Download available on the CD of Sandec’s Training Tool and from the Internet.
1.3 What are the environmental health objectives?
Ñ The environmental health objectives comply with the Millennium Development Goals (MDG) of the UN. Improving water supply and sanitation will contribute to meeting especially MDG 4 (reduce child mortality), MDG 5 (improve maternal health) and MDG 7 (ensure environmental sustainability).
The aim of environmental health is to as compared with the rate in the best ment is a threat to the mother and her prevent diseases and to create an envi- performing region. In terms of just diar- unborn child. Childbirth requires, for ex- ronment that supports health. To achieve rhoea and lower respiratory infections, ample, safe water and sanitary condi- this goal, the environmental factors like- two of the most significant child killers, tions. ly to affect health must be assessed and environmental interventions could pre- controlled. In September 2000, a Mil- vent the deaths of over two million chil- Goal 7: Ensure environmental lennium Declaration was endorsed by dren under the age of five every year, sustainability 189 United Nations member states. It and thus help achieve a key target of this Diarrhoeal diseases associated with a led to eight Millennium Development MDG – a two-thirds reduction in the rate lack of access to safe drinking water Goals (MDGs) to be reached by 2015. of mortality among children in that age and inadequate sanitation result in nearly The MDGs contain commitments to re- category. 1.7 million deaths annually. Household duce poverty and hunger, to tackle ill use of biomass fuel and coal by over health, gender inequality, lack of edu- Goal 5: Improve maternal health one-half of the world‘s population, re- cation, lack of access to clean water, Environmental interventions can contrib- sults in 1.5 million annual deaths from and environmental degradation.
Sandec Training Tool: Module 2 1 – Definitions & Objectives
Good health is both an end and a means Further questions of sustainable livelihood. For poor peo- health-care costs and healthy life years Ñ Can the Millennium Development Goals ple, good health is an essential asset in lost, particularly as a result of diarrhoeal be attained by 2015? the pursuit of their livelihood; however, diseases, intestinal nematode infec- Ñ How can water and sanitation improve- their homes and work environments of- tions and related malnutrition. Providing ments contribute to the other Millennium ten threaten their health. Since improving access to improved drinking water Development Goals, i.e. eradicate extreme environmental health is a sustainable and sources in developing countries would poverty and hunger (MDG 1), achieve cost-effective means of improving people’s universal primary education (MDG 2), health, it forms the base for the creation of reduce considerably the time spent by promote gender equality and empower sustainable livelihoods and eradication of women and children in collecting wa- women (MDG 3), combat HIV/AIDS, poverty. (Cairncross et al., 2003, p. 6) ter. Providing access to improved sanita- malaria and other diseases (MDG 6), tion and good hygiene behaviours would and develop a Global Partnership for tions in such environmental exposures help break the overall cycle of faecal-oral Development (MDG 8)? will both improve the health and the lives pathogen contamination of water bodies, of urban slum dwellers – one of the key yielding benefits to health, poverty re- Additional info Ñ UN (2007): The Millennium Develop- targets of MDG 7. duction, well-being and economic devel- ment Goals Report 2007. www.un.org/mil- A key target of the Millennium De- opment. (Prüss-Üstün et al., 2006) lenniumgoals/pdf/mdg2007.pdf (last velopment Goals (MDG 7) is halving by accessed 15.07.08) 2015 the proportion of people without Ñ WHO/UNICEF (2006): Meeting the MDG sustainable access to safe drinking wa- drinking water and sanitation target: The ter and sanitation. Globally, WHO has urban and rural challenge of the decade. estimated that the economic benefits Geneva. www.who.int/water_sanitation_ health/monitoring/jmp2006/en/ (last of investments in meeting this target accessed 15.07.08) would outweigh costs by a ratio of about Download available on the CD of Sandec’s 8:1. These benefits include gains in eco- Training Tool and from the Internet. nomic productivity as well as savings in Figure 4: UN logo.
1.4 Why should the Green Sustainability Agenda also be considered?
Ñ The so-called ‘Brown Agenda’ focuses on environmental health and the ‘Green Agenda’ on the health of the environment. Thus, the Green Agenda centres on the Environmental Sustainability Agenda. Ñ To ensure a sustainable effect of environmental health improvements, both agendas should be reconciled.
The so-called ‘Brown Agenda’ was es- impact of environmental changes. Envi- tablished to reach the objectives of envi- ronmentalists are, however, more con- ronmental health. It focuses on environ- cerned with the surrounding natural en- mental health as defined above, whereas vironment, such as the river. Thus, the the ‘Green Agenda’ is concerned with Green Agenda might favour wastewater the health of the environment. Of course, treatment to reduce environmental pollu- control of environmental pollution is tion, whereas the Brown Agenda would likely to benefit both, however, the prior- give priority to getting human waste and ities of the two agendas sometimes dif- excess water away from households and fer. The major health impacts are usual- residential neighbourhoods, even at the Figure 5: Concentric domains of the urban ly caused by factors affecting people in cost of polluting some local streams. environment. (Adapted from Cairncross et al., 2002, p. 10) their homes or in their neighbourhoods, (Cairncross et al., 2002, p. 9) whereas the most obvious effects on the environment in general are relatively re- The ‘Brown’ Environmental The ‘Green’ Sustainability mote from them. The difference is illus- Health Agenda Agenda trated by Figure 5. It illustrates the urban First order impact Human health Ecosystem health environment as a series of concentric do- mains, from the individual household to Timing Immediate Delayed the city as a whole and its environs. A Scale Local Regional and global city’s environmental infrastructure, such Worst affected Lower-income groups Future generations as water supply, sewerage, drainage, and refuse collection systems, is or- Priority for water Increase quantity, quality Prevent over-use and ganised in a hierarchy corresponding to and accessibility degradation these domains. In general, the closer to the households, the greater the health Table 3: Characteristics of the two agendas. (Satterthwaite, p. 4)
Sandec Training Tool: Module 2 1 – Definitions & Objectives
What are the priorities of most Green A project in Kunming, China, aiming at reducing pollution of lake Dianchi, reconciles Agenda proponents? both the Green Sustainability and the Brown Environmental Health Agenda. Kunming, Zurich’s sister city in China, is determined to tackle its wastewater problems. • ‘Ecological solutions’ prioritised with Technical and social measures based on nutrient recycling – a long-established principle in no knowledge of local contexts China – are being developed with Eawag’s support. – Yet local contexts almost always The drinking water supply for Kunming’s population is largely drawn from lake Dianchi. How- influence the most appropriate so- ever, this shallow lake is heavily contaminated with phosphorus as a result of urban wastewa- lutions ter discharges and regional agriculture. For some time now, the abstraction of drinking water from the lake has been steadily reduced, and withdrawals will probably be stopped altogether • Scant regard for engagement with in the near future. In view of this precarious situation, the authorities have called for efforts to those who lack good provision restore the lake water quality to its 1960 standard. – Solutions promoted often do not Measures taken at source provide important alternatives to conventional treatment technolo- work gies. China has a long tradition of nutrient recycling, especially in rural areas where urine has – Criticising solutions that work well long been used as a fertiliser. Does this mean that urine separation would be a possible op- tion for improving the water quality of lake Dianchi? To investigate this question, a three-part • Spurious statistics and associations project, financed by the Swiss research programme NCCR North-South, was conducted by revealing the causes of inadequate Eawag in Kunming. It comprised: provision of water/sanitation and wa- Ñ analyses of wastewater flows in Kunming and simulation of the outcome of possible ter shortages measures; • Northern concepts applied out of Ñ a survey of the relevant stakeholders acceptance of source control measures, introduction context of urine separation and possible decision-making paths; and – Encouragement of donor agencies Ñ launching of a pilot project to test urine-diverting waterless toilets in a rural area. to spend too much on what is not Persistence and courage to pursue a sustainable solution a priority (Green Agenda is easi- Overall, urine separation contributed significantly to solving Kunming’s wastewater problems, er to implement, easier to spend though different approaches are probably required in rural and urban areas. It is also obvious large sums on, often appreciated by that significant efforts are being undertaken by Kunming City to restore the quality of the lake, which has been deteriorating due to intense population pressure. There is no standard solu- middle and higher-income groups). tion for this extremely challenging task. Neither upgrading of Kunming’s sewerage system, (Satterthwaite, p. 10) combined with a diversion of the treated wastewater, nor urine separation alone will solve the problems of lake Dianchi. A combination of measures is necessary, along with persistence The two agendas differ in priorities; how- and courage to experiment, until appropriate solutions are developed and tested prior to their ever, several environmental health as- large-scale implementation. (Larsen et al., 2007) pects overlap both agendas. If the Brown or Green Agenda supporters also consid- er the other agenda, they could often “kill two birds with one stone”. There- fore, a reconciliation of both agendas should be the objective pursued. Water and sanitation’s obvious advan- tages of the Brown and Green Agendas: • Directly addressing human needs • Performs well in relation to future generations: Photo 2: Industry and agriculture side by Photo 3: Algae in the polluted lake Dianchi – Does not make heavy use of non- side in Kunming, near lake Dianchi. (Source: from which people used to draw their drinking Melanie Savi) water. (Source: Edi Medilanski) renewable resources – Does not generate large volumes of hazardous non-biodegradable Further questions waste Ñ What makes it so difficult to reconcile both agendas? – Does not contribute much to green- Ñ Is implementation of the Brown Agenda alone a selfish measure with regard to future house gas emissions – Based on a renewable resource (al- Additional info though with limits) Ñ Cairncross (2002): Environmental health and the poor – our shared responsibility. – Does not need much freshwater in www.lboro.ac.uk/well/ (last accessed 15.07.08) relation to total flows in most na- Ñ IIED (2006): “Environment & Urbanization Brief – 13. Ecological Urbanization.” Environment tions and locations. & Urbanization 18(1). www.iied.org/pubs/ (last accessed 15.07.08) (Satterthwaite, p. 5) Download available on the CD of Sandec’s Training Tool and from the Internet.
Sandec Training Tool: Module 2 2 – Introduction
2.1 What is the burden of disease?
Ñ Environmental health hazards account for 21 % of the overall disease burden worldwide. Ñ Developing regions carry a disproportionately heavy health burden with regard to communicable diseases and injuries. Ñ Children suffer a disproportionate share of the environmental health burden.
The environment in which we live has a significant effect on our health. Some examples of the health impact of water supply, sanitation and hygiene are listed hereafter. • Diarrhoea causes 2 million deaths per year, mostly amongst children under the age of five. • About a third of the population of the developing world is infected with in- testinal worms. • 6 – 9 million people are estimated to be blind from trachoma. • 200 million people in the world are
infected by schistosomiasis (bilhar- 0% 1% 2% 3% 4% 5% 6% 7% zia), 20 million of which suffer severe Frac tion of to tal global burden of diseas e in D ALYs * consequences. Environment al fraction Non-environment al fraction • Guinea worm eradication has made dramatic progress over the past ten Figure 6: Diseases with the largest environmental contribution. (Prüss-Üstün et al., 2006, p. 11) years, with the number of cases drop- (For each disease the fraction attributable to environmental risks is shown in dark green. Light green plus dark green represents the total burden of disease). ping by 95 % from 890 000 in 1989 to * DALY or “Disability-Adjusted Life Year” represents a weighted measure of death, illness and less than 50 000 today. disability (cf. Chapter 2.3). • An estimated 1.1 billion people are without access to water supplies, and 2.4 billion lack adequate sanita- tion. The number of people without access to adequate sanitation rose by around 150 million in the period 1990 to 2000. (Cairncross et al., 2002, p. 3) Figure 6 lists the 24 diseases with the largest environmental contribution on a global scale. Diarrhoea has by far the big- gest environmental fraction.
Local differences The burden of disease is not evenly dis- tributed in the world. Developing re- gions carry a disproportionately heavy Figure 7: Environmental disease burden in deaths per 100 000 people. burden regarding communicable diseas- (Prüss-Üstün et al., 2006, p. 10) es and injuries. In 2002, infectious dis- eases made up the largest overall differ- vironmental burden per capita of diar- risks and access to health care servic- ence between the regions (as classified rhoeal diseases and lower respiratory es. The world map, containing the envi- by WHO). The total number of healthy infections was 120 – 150 times greater ronmental disease burden in deaths per life years lost (DALYs) per capita as a re- in certain subregions of developing coun- 100 000 people, illustrates significant su- sult of environmental burden per capita tries than in the subregions of developed bregional differences. (Prüss-Üstün et was 15 times higher in developing coun- nations. These differences arise from al., 2006, p. 11) tries than in developed nations. The en- variations in exposure to environmental
Sandec Training Tool: Module 2 2 – Introduction
Other; 19% I ntesti nal nema tode Diarrhoeal diseases; 16% infection; 1.5% Lower re spiratory Diarrhoeal Drowning; 2% infections; 11% Other; 3 4% diseases; 2 9% Total neuropsychiatric Ma lnutrition; 4% disorders; 7% Childhood clus ter Perina tal conditions; 3% Cardiovascular diseases; 5% diseases; 7% Chronic obstructiv e Lower re spiratory Perina tal Other unintentional pulmonary disease; 3% infections; 16% conditions ; 6% injuries ; 6% Total cancers; 4% Total neuropsychiatric Ma laria; 5% Ma laria; 10% disorders; 6% Figure 8: Main diseases contributing to the environmental burden of diseases for the total population (left) and among children between 0 and 14 years of age (right). (Prüss-Üstün et al., 2006, p. 62)
Children suffer most Prevention is better than cure The children are disproportionately af- The World Health Organization has estimated (WHO 2000) that environmental health haz- ards account for 21 % of the overall disease burden worldwide, affecting mainly developing fected by the environmental disease bur- countries, especially the poorest regions of the world. Environmental improvements are often den. Globally, the per capita number of more cost-effective health measures than the curative efforts of the health sector. After all, healthy life years lost to environmental prevention is better than cure. (Cairncross et al., 2003, p. 6) risk factors is about 5 times greater in children under five than among the total population. Diarrhoea, malaria and respi- ratory infections all have very large frac- tions of disease attributable to environ- ment, and also are among the biggest killers of children under the age of five. In developing countries, the environmen- tally-related fraction of these three dis- eases accounted for an average of 26 % of all deaths in children under five. On average and per capita, children in de- veloping countries lose 8 times more healthy life years than their counterparts in developed nations due to environmen- tally-caused diseases. In certain very poor regions of the world, however, the disparity is far greater: the per capita healthy life years lost as a result of child- hood lower respiratory infections is 800 times greater, 25 times greater due to road traffic injuries and 140 times great- er due to diarrhoeal diseases. Even these statistics fail to capture the longer-term effects of exposure occurring at a young age that manifest themselves as dis- ease only years later. (Prüss-Üstün et al., 2006, p. 13)
Further questions Ñ What are the reasons for the differences in disease burden between the developing countries (e. g. when comparing South- America to Africa)? Photo 4: Child in Mauritania. (Source: Eawag/Sandec) Ñ Why do children suffer much more from diseases? Ñ What are the specific differences in ex- Additional info posure to environmental risks between de- Ñ Cairncross (2003): Health, environment and the burden of disease; A guidance note. veloped and developing regions? London, DFID. www.dfid.gov.uk/Pubs/files/healthenvirondiseaseguidenote.pdf (last accessed 15.07.08) Ñ By far not all people in developing coun- tries can afford to visit a doctor in case of Ñ Prüss-Üstün (2006): Preventing disease through healthy environments. Towards an illness. How does this affect statistics? estimate of the environmental burden of disease. Geneva, WHO. www.who.int/quantifying_ How wrong do you think they are and how ehimpacts/publications/preventingdisease/en/index.html (last accessed 15.07.08) could statistics be improved? Download available on the CD of Sandec’s Training Tool and from the Internet.
Sandec Training Tool: Module 2 10 2 – Introduction
2.2 What is the environmental health impact of water and sanitation?
Ñ Almost half of the environmental health-related disease burden can be attributed to unsafe water and sanitation. Ñ By improving drinking water and sanitation services, diarrhoeal disease morbidity could, for example, be reduced by 25 – 45 %.
Diet related illness Definition: “Attributable Fraction” 11 % Injuries If a risk factor (e. g. agricultural pesti- 9 % Addictive Malnutrition Indoor smoke substances 42 % 30 % cides) causing health problems or deaths 7 % to the exposed members of a communi- Other 13 % ty were removed from the environment (e. g. by legislative action), we would ex- Environ- mental pect a decline in the overall number of Health 21 % health problems or deaths in the com- Unsafe water munity. The proportional reduction in the Sexual Health & sanitation issues 48 % number of health problems or deaths 19 % as a result of reducing the risk factor is Figure 9: The global disease burden, classified by risk factors, reveals that 21 % are associated to known as the “attributable fraction”. In environmental health. In this category, almost half the disease burden can be attributed to unsafe other words, it is the proportion of all water and sanitation. (WHO, 2002 in Cairncross et al., 2003, p. 2) health problems or deaths in the commu- nity attributable to the risk factor. (Prüss- Üstün et al., 2006, p. 25)
Health impact The map (figure 10) reveals that the pro- portion of DALYs attributable to the risk factor “unsafe water” is particularly high in Africa, some parts of Asia and South America. Figure 11 illustrates the high extent of diarrhoea morbidity reduction through intervention activities in sanitation, wa- ter treatment and hygiene. Figure 12 re- veals the impact of improved water sup- ply, sanitation and hygiene on morbidity and mortality for six common diseases and child mortality.
Figure 10: Burden of disease attributable to unsafe water (% DALYs in each subregion, DALY: cf. Chapter 2.3). (WHO, 2002, p. 69) Further questions 45 Ñ How meaningful are the aforementioned 39 studies on different disease-reducing interventions? What are their impacts and 32 78 77 limitations?
25 Ñ The burden of disease attributable to 55 unsafe water is only shown at the global and regional level. What are the differenc- Reduction (%) 29 es at the local level? 26 27
4
Expected reduction (median %) Additional info Improved Improved Improved Household Ascariasis Diarrhoeal Dracuncu- Hookworm Schisto- Trachoma Child Ñ WHO/UNICEF (2005): Water for Life – (4) disease liasis infection somiasis (7) mortality drinking sanitation hygiene water (19) (2) (1) (3) (6) water treatment Making it happen. WHO/UNICEF, Gene- Disease (number of studies) va. www.who.int/water_sanitation_health/ Figure 11: Reduction in diarrhoeal disease Figure 12: Impact of improved water supply, monitoring/jmp2005/en/index.html (last morbidity resulting from improvements sanitation and hygiene on morbidity and mor- accessed 15.07.08) in drinking water and sanitation services. tality for six common diseases: evidence from Download available on the CD of Sandec’s (Fewtrell et al., 2005 in WHO/UNICEF, 2005, 42 studies. (After Esrey et al., 1991 in WHO, Training Tool and from the Internet. 2005, p. 20)
Sandec Training Tool: Module 2 11 2 – Introduction
2.3 What is the standardised disease measure?
Ñ The standardised disease measure is the Disability-Adjusted Life Year (DALY). One DALY is equal to one lost year of healthy life. Ñ The DALY concept combines in one measure morbidity (years lived with disability) and mortality (years of life lost due to premature death).
The concept of the DALY (Disability- Calculation Adjusted Life Year) was introduced in the DALYs for a disease or health condition Global Burden of Disease Study in an ef- are calculated as the sum of the years of fort to finding a common measure to as- life lost due to premature mortality (YLL) sess priorities among different diseases in the population, and the years lost due and health problems. Murray and Lopez to disability (YLD) for incident cases of did not think it appropriate or necessary the health condition: to attach a monetary value to the burden of disease. They developed the DALY as DALY = YLL + YLD an alternative, a concept that takes the lost life years as a benchmark and in- YLL = Number of deaths × Standard life cludes the following design decisions: expectancy at age of death in years YLD = Number of incident cases × Disability Figure 13: Example of an individual person’s life and health with a qualitative visualisation • Ideal lifespan. This was needed in weight × Average duration of the case until of DALY’s lost due to a disease and premature order to define the age before which remission or death (years) death. death could be regarded as prema- ture, and years of life considered lost. The “disability weight” is a weight fac- indicator conditions.
Sandec Training Tool: Module 2 12 2 – Introduction
2.4 What are the main causes for water and sanitation-related diseases?
Ñ Diseases can be classified by their transmissibility into communicable (e. g. caused by microbiological contamination of drinking water) and non-communicable (e. g. caused by chemicals in drinking water).
Pathogens Diseases can be divided into communi- parasitic worm (helminths) eggs with Microbiological Viruses Communicable cable diseases, such as typhus or hook- their faeces. The microbiological con- contaminants in Bacteria diseases worm infection, and non-communicable taminants in drinking water are virus- drinking water Protozoa Helminth eggs disease, such as diabetes or heart dis- es, bacteria, protozoa or helminth eggs. Origins ease. The communicable diseases can Chemicals in drinking water can cause Natural spread rapidly through direct person-to- non-communicable diseases such as Chemical Agriculture Non-communi- contaminants in Human person contact (e. g. the rotavirus), or cancer. These chemicals can have dif- cable diseases settlements drinking water they can be transmitted indirectly, for ex- ferent origins, such as from natural or Industry ample through human contact with wa- human activities (agriculture, settle- ter contaminated by humans excreting ments, industry or water treatment). Figure 14: Origins of communicable and non- communicable diseases.
2.5 What are the main transmission routes of pathogen-related diseases?
Ñ Diseases related to water supply and sanitation are mostly transmitted via a faecal-oral mechanism by pathogens found in human excreta. Ñ Transmission following some typical routes is summarised in the so-called “F Diagram”.
Most diseases associated with water supply and sanitation, such as diarrhoea, are spread by pathogens (disease-caus- ing organisms) found in human excreta (faeces and urine). The faecal-oral mech- anism, in which some of the faeces of an infected individual are transmitted to the mouth of a new host through one of a variety of routes, is by far the most significant transmission mechanism: it accounts for most diarrhoea and a large number of intestinal worm infections. This mechanism works through a varie- ty of routes, as shown by the so-called “F Diagram” (cf. Figure 15). (WHO, 2005, p. 10) Some pathogens also follow slightly different routes, such as leaving or en- tering the host through the skin or using Figure 15: The F Diagram. (Adapted from DFID/WELL, 1998, p. 64) insects as alternate host. This is ex- plained in detail in chapter 3.1. In addition to the “hygiene-related” Further questions transmission routes, diseases may also Ñ Could animals play a role in transmission routes? be caused by poorly managed sanita- Ñ What are possible transmission routes from faeces to fields, or from faeces to fluids? tion. If latrines or sewerage systems are poorly managed, surface or groundwater Additional info can be contaminated and thus affect the Ñ See later in this module. quality of drinking water.
Sandec Training Tool: Module 2 13 2 – Introduction
2.6 What factors influence occurrence and non-occurrence of infection?
Ñ Pathogen and host factors influence infection or non-infection of a new host. Ñ The potential risk to public health is determined through pathogens analysed in faecal sludge and wastewater. The actual risk is determined by the number of actual infections, as shown by epidemiological studies.
Pathogen factors Host factors Possible health If a person comes into contact with path- outcome of worm eggs in faecal sludge by e. g. • Excreted load • Natural immunity • No transmission ogens, this does not necessarily mean • Latency • Aquired immu- 80 – 90 % will already have a major pub- • Transmission and • Persistence nity (e.g. infec- that an infection occurs. Several factors tion, vaccination, symptomless lic health effect. Since fewer worms will • Multiplication infection at the pathogen and host level influence mother’s milk) be discharged on the ground and into • Infective dose + • Age and Sex • Transmission and infection transmission and infection (cf. Figure • Health state with manifest ponds, transmission and people’s worm 16). Agricultural or aquacultural use of • Nutrition sickness burdens will also be reduced. With virus- excreta and wastewater can, for exam- es, bacteria and protozoa, higher removal ple, only lead to an actual risk to public degrees (99.9 – 99.999 %) are required. health if all of the following occurs: Figure 16: Pathogen and host factors Pathogens have varying degrees of re- a) Either an infective dose of an excret- influencing the health outcome. sistance, however, worms are among ed pathogen reaches the field or the more resistant, with Ascaris surviv- pond or the pathogen multiplies in Die-off or persistence of excret- ing longest. Temperature, dryness and the field or pond to form an infective ed pathogens is an important factor in- UV-light are the main factors influencing dose. fluencing transmission. In principle, all die-off. (Strauss, 1994, p. 3) b) This infective dose reaches a human pathogens die off upon excretion. Prom- host. inent exceptions are pathogens whose Average survival time in c) This host becomes infected. intermediate stages multiply in interme- wet faecal sludge [days] d) This infection causes disease or fur- diate hosts, as Schistosoma that multiply Organisms In temperate In moderate ther transmission. in aquatic snails and are later released climate climate into the water body. Another important (10 – 15° C) (20 – 30° C) (a), (b) and (c) constitute the poten- factor is the infective dose of a patho- Viruses <100 <20 tial risk and (d) the actual risk to public gen. It is the dose required to create dis- Bacteria health. If (d) does not occur, the risks ease in a human host. For helminths, Salmonella <100 <30 to public health remain only potential. protozoa and viruses, the infective dose Cholera <30 <5 (Strauss, 1994, p. 1) is low (< 102). For bacteria, it is me- Different pathogen factors contribute dium (104) to high (> 106). Manifesta- Faecal <150 <50 coliforms* to the potential risk: The excreted load tion of disease is different for the vari- is the number of pathogens excreted in a ous pathogens: with viruses, protozoa Protozoa certain amount of waste. The time need- and bacteria, an infected person will ei- Amoebic <30 <15 ed until the excreted pathogens become ther become sick or not. With helminths, cysts infective is described as latency. Multi- however, an infected person will exhib- Helminths plication describes whether the patho- it various degrees of disease intensities Ascaris eggs 2 – 3 years 10 – 12 gens can multiply outside the host, and depending on the number of worms it months finally the infective dose expresses the carries in its intestine. Thus, implemen- number of pathogens required to cause tation of a nightsoil or wastewater treat- an infection. ment strategy, leading to a reduction Table 5: Example of a pathogen factor: survival time of different pathogens. When exposed to the drying sun, all the survival periods are Laxmi’s short life – the accumulative much shorter. burden of disease * Faecal coliforms: commensal bacteria of the It was not only one severe illness that human intestine used as indicator organisms for excreted pathogens. (Strauss, 1994, p. 4) caused Laxmi’s early death at the age of only three. During her entire life she had to fight one disease after another, Further questions among them acute respiratory infection, Ñ During an infection, health will be re- diarrhoea, measles, and fever. Due to duced and the person will become more her poor nutrition and health condition, vulnerable to further infections. What can a she was affected by numerous infec- person do to break this vicious circle? tions that led to her early demise. Ñ The graph of Laxmi’s short life shows a normal weight for the first six months, despite of several diseases. What factors Figure 17: The graph illustrates the age-dependent development of the weight of a healthy lead then to the break-in? What are the child (dashed line) and of Laxmi – a child from a developing country (solid line). (Dooley, 2008, UNICEF Presentation) effects of disease frequency?
Sandec Training Tool: Module 2 14 2 – Introduction
2.7 What particular situations can increase the potential and actual risk of disease?
Ñ Some emergency situations can lead to an increased disease risk for an entire community, such as flooding, war or industrial accidents.
The greatest waterborne risk to health in quality in different ways. When people low immunity due to malnutrition or the most emergencies is the transmission of are displaced by conflict and natural dis- burden of other diseases, then the risk faecal pathogens caused by inadequate aster, they may move to an area where of an outbreak of waterborne disease sanitation, hygiene and protection of wa- unprotected water sources are contami- is increased. The quality of urban drink- ter sources. Some disasters, including nated. When population density is high ing water supplies is particularly at risk those caused by or involving damage to and sanitation is inadequate, unprotect- following earthquakes, mudslides and chemical and nuclear industrial installa- ed water sources in and around the tem- other structurally damaging disasters. tions or spillage in transport or volcanic porary settlement are highly likely to Water treatment works may be dam- activity, may create acute problems from become contaminated. If there is a sig- aged, causing untreated or partially chemical or radiological water pollution. nificant prevalence of disease cases and treated water to be distributed, and Different types of disaster affect water carriers in a population of people with sewers and water transmission pipes may be broken, causing contamination of drinking water in the distribution system. Cholera epidemic in the Democratic Republic of the Congo Human population movements on a large scale as a result of war, conflict or natural catas- Floods may contaminate wells, bore- trophes have been tragically common in recent years. The forced migration or displacement holes and surface water sources with of large numbers of people often oblige them to live in crowded, unhygienic and impover- faecal matter washed from the ground ished conditions, which, in turn, heighten the risk of infectious disease epidemics. This was surface or from overflowing latrines and the cause of the cholera epidemic in the Democratic Republic of the Congo, in the aftermath sewers. During droughts, people may of the crisis in Rwanda in 1994. In July of that year, between 500 000 and 800 000 people crossed the border to seek refuge in the outskirts of the Congolese city of Goma. During the be forced to use unprotected water sup- first month after their arrival, close to 50 000 refugees died. The extremely high crude mortal- plies when normal supplies dry up; as ity rate of 20 – 35 per 10 000 per day can be associated with an explosive outbreak of com- more people and animals use fewer bined cholera and shigella dysentery. The speed of transmission and the high attack rate were water sources, the risk of contamination related to the contamination with Vibrio cholerae of the only available source of water, Lake is increased. Emergency situations that Kivu, and the absence of proper housing and sanitation. The problems associated with peo- ple living in high-density environments are not limited to emergency areas, such as refugee are appropriately managed tend to sta- camps. Rapid urbanisation that has become common in many countries in the 21st century bilize after a matter of days or weeks. means that cities are now home to over half the world’s population. Uncontrolled urbanisation Many develop into long-term situations is characterised by expanding metropolitan areas, worsening environmental degradation, that can last for several years before a increasing inequity and the growth and proliferation of slums and informal settlements. permanent solution is found. Water qual- Indeed, a third of global urban dwellers, or a billion people, live in slums and informal settle- ments where they exist in cramped, congested living conditions, without access to safe wa- ity concerns may change over that time, ter, sanitation, safe food, decent shelter or meaningful employment. (WHO, 2007b, p. 21) and water quality parameters that pose long-term risks to health may become more important. (WHO, 2006, p. 104)
Further questions Ñ What factors other than lack of water and sanitation services could be respon- sible for the increased disease burden in emergency situations? Ñ What measures should be taken in such situations? Ñ Do developed regions have similar problems in emergency situations?
Additional info Ñ Connolly (2005): Communicable disease control in emergencies – A field manual, WHO. www.who.int/hac/techguidance/pht/ communicable_diseases/field_manual/en/ (last accessed 15.07.08) Download available on the CD of Sandec’s Photo 5: Washing facility in a temporary refugee camp. (Source: WEDC © Bob Reed) Training Tool and from the Internet.
Sandec Training Tool: Module 2 15 2 – Introduction
2.8 What are the sources of pathogens and places of exposure?
Ñ Pathogens causing water and excreta-related diseases are mainly found in faeces, but also in urine, greywater, industrial wastewater, and stormwater. Ñ The main areas or activities leading to pathogen exposure in the example of excreta reuse include toilets, as well as handling and reuse of excreta as fertiliser. Residents of these areas or those conducting such activities are often at greater risk of infection than others.
Wastewater Sources of pathogens are closely related Possible sources of pathogens components to sanitation, excreta and waste reuse. Though sanitation systems that close • Contain the major amounts of pathogen, enteric (bowels, stomach) infections. the loop generally have positive impacts on the health of users, certain risks still • Enteric infections can be transmitted by pathogenic species of bacteria, Faeces viruses, parasitic protozoa, and helminths. prevail. And although a source-separat- • From a risk perspective, exposure to untreated faeces is always considered ing system tries to separate hygienically unsafe. critical substances (mainly faeces) from those that are safe, cross-contamination • Only a few diseases are transmitted through urine. may still occur. • Generally low health risks for transmission of diseases found in urine, Urine Depending on the location of expo- except for Schistosomiasis (in tropical areas). sure, certain people are at greater risk • Faecal cross-contamination through urine poses the highest health risk. of being infected than others, name- • Mainly laundry, washing diapers, food. ly children playing near toilets, pit emp- • Opportunistic pathogenic bacteria originating from growth within the tiers, collectors, farmers reusing waste, actual system. and consumers of products that came Greywater • Main greywater hazard from faecal cross-contamination – however, this is into contact with reused waste. Occu- less acute than from urine and is limited to washing faecally contaminated pations exposed to a higher risk level laundry (i.e. diapers), childcare, anal cleansing, and showering. are described in other modules (Mod- Industrial • Slaughterhouse, food industry (plant pathogens). ules 4 – 6). wastewater
Stormwater • For example run-off from ground (animal faeces). Table 6: Main risks from different wastewater components. (Heeb et al., 2007, Module 4-5)
Photo 6: Woman emptying compost in Dhaka, Bangladesh. (Source: Eawag/San- Photo 7: Man working in a compost container in India. (Source: dec) Eawag/Sandec)
Sandec Training Tool: Module 2 16 2 – Introduction
Area or activity leading to pathogen Transmission route Technical measure Behavioural measure exposure Direct contact; transport to ground- Water for hand-washing available; Washing hands; keeping toilet area water; environmental contamination. elevated collection chamber; lined clean. Toilet collection chamber (no seepage to groundwater or environment).
Direct contact. Ash, lime or other means of Wearing gloves; washing hands; Primary handling – reducing microorganisms at toilet; addition of ash, lime or other means collection and transport informed persons collecting and of reducing the microbial content transporting excreta. during use.
Direct contact; environmental Suitable choice of location; treatment Wearing gloves and protective Treatment contamination. in closed systems; information signs clothing; washing hands; avoid in place. contact in treatment areas.
Secondary handling – Direct contact. Informed farmers reusing excreta; Wearing gloves; washing hands; use, fertilising special equipment available. washing the equipment used.
Direct contact; transport to surface Working excreta into the ground; Avoid newly fertilised fields. Fertilised field and groundwater. information and signs.
Consumption; contamination of Choice of suitable crop. Proper preparation and cooking of Fertilised crop kitchen. food products; cleanliness of kitchen surfaces and utensils.
Table 7: Places of exposure. (Schönning, 2004)
Further questions Ñ Treatment of excreta for safe disposal or reuse is highly recommended, however, it may expose the workers or recyclers to a much greater risk of infection. How can this dilemma be solved? Ñ How important are additional pathogen sources (such as saliva or blood) to the water and excreta-related pathogens? Ñ Would a centralised sanitation system be more desirable than a decentralised one from a health perspective?
Additional info Ñ Schönning (2004): Guideline for the safe use of urine and faeces in ecologi- cal sanitation systems. Stockholm, Swed- ish Institute for Infectious Disease Control (SMI). www.ecosanres.org/pdf_files/ESR- factsheet-05.pdf (last accessed 15.07.08) Download available on the CD of Sandec’s Training Tool and from the Internet. Photo 8: Farmers using compost on their fields in India. (Source: Eawag/Sandec)
Sandec Training Tool: Module 2 17 3 – Diseases
3.1 What is the environmental classification of pathogen-related diseases?
Ñ The water and excreta-related communicable diseases can be categorised by their common environmental transmission routes. Thereby, an important distinction is made between water-washed and waterborne diseases.
Classification of diseases into communi- Examples of pathogens Categories and typical cable (pathogen-related) and non-com- (Bold = described in this Control strategies transmission routes municable (e. g. caused by exposure to Module) chemicals) was discussed in the chap- Feco-oral waterborne and Hepatitis A and E (virus) Improve water quantity, ter “Definitions”. The communicable water-washed diseases Rotavirus availability, and reliability diseases can be further subdivided. This (water-washed disease Cholera (bacterium) chapter describes the currently used en- control); Improve water quality Amoebiasis (protozoa) vironmental classification and uses the (water-borne disease control); hygiene education. biological classification to discuss the Ascariasis (helminth) different diseases. An environmental classification of dis- Non-feco-oral water-washed Skin infection: Improve water quantity, ease groups, such as water-related and diseases Leprosy (bacterium) availability and reliability; excreta-related diseases, is more use- hygiene education. Eye infection: ful to environmental engineers than one Trachoma (bacterium) based on biological types because it groups the diseases into categories of common environmental transmission Geohelminthiases Ascariasis (helminth) Sanitation; effective treatment routes. Thus, an environmental interven- Hookworm infection of excreta or wastewater prior tion designed to reduce transmission of (helminth) to reuse; hygiene education. pathogens in a particular category is like- ly to be effective against all pathogens in that category, irrespective of their bio- logical type. Water-based diseases Legionellosis (bacterium) Decrease contact with An important distinction is made Clonorchiasis (helminth) contaminated water; improve domestic plumbing; public between “waterborne” and “water- Schistosoma (helminth) education; sanitation; washed” diseases. Water-borne diseas- Guinea worm infection treatment of wastewater prior Ingestion or es are caused by pathogens in the water through skin (helminth) to reuse, public education; a person drinks. Whereas water-washed drying of flood-damaged diseases are diseases where transmis- homes. sion is facilitated by insufficient quanti- Insect-vector diseases Water-related: Decrease passage through ties of water (regardless of its quality), Malaria (protozoa) breeding sites; larvicide appli- thus, directly linked to issues of per- cation; biological control; use Dengue (virus) sonal and domestic hygiene. All diseas- of mosquito netting and es, commonly considered waterborne, Yellow fever (virus) impregnated bed nets; can also be transmitted by the water- Excreta-related: improve stormwater drainage; public education. washed route. Epidemiological studies Fly-borne and cockroach- have revealed that the latter is more borne excreted infections. important under conditions of water Rodent-vector diseases Rodent-borne excreted Rodent control; hygiene scarcity, such as in rural and periur- infections. education; decreased contact ban areas of developing countries. The with contaminated water; water-washed transmission route is like- public education. ly to be important even in areas with adequate water supplies but poor Taeniases Beef and pork tapeworm Sanitation; effective treatment infections. of excreta or wastewater personal and/or domestic (including prior to reuse; hygiene food) hygiene. Table 8 provides an over- education. proper cooking of view of an environmental classification meat and improved meat of water and excreta-related diseases. inspection. (Mara et al., 1999, p. 334) Table 8: Unitary environmental classification of water and excreta-related diseases. (Summarised Further questions from Mara et al., 1999, p. 335) Ñ Is it better to use unsafe water to wash hands than no water at all?
Sandec Training Tool: Module 2 18 3 – Diseases
3.2 What are the main microbial hazards associated with water and excreta?
Ñ Virus infections such as rotavirus or hepatitis A and E. Ñ Bacterial infections such as cholera or trachoma. Ñ Protozoal infections such as amoebiasis. Ñ Infections with helminths (parasitic worms), such as ascaris lumbricoides, hookworm, guinea worm or schistosoma.
Communicable diseases caused by path- become undetectable after a certain pe- peaks in pathogen concentration may in- ogenic bacteria, viruses and parasites riod. Pathogens with low persistence crease disease risks considerably, and (e. g. protozoa and helminths) are the must rapidly find new hosts and are may also trigger outbreaks of water- most common and widespread health more likely to be spread by person-to- borne disease. (WHO, 2006, p. 121) risks associated with drinking water. person contact or poor personal hygiene On account of the large number of While typical waterborne pathogens are than by drinking water. The most com- water and excreta-related diseases, we able to persist in drinking water, most mon waterborne pathogens and para- cannot describe them all in this Module. do not grow or proliferate in water. Af- sites are those with a high infectivity, We have selected the most relevant dis- ter leaving the body of their host, most which can either proliferate in water or eases and exemplified various biologi- pathogens gradually lose viability and the possess high resistance to decay out- cal types along with different transmis- ability to infect. The rate of decay is side the body. Microbial water quality sion routes. usually exponential, and a pathogen will may vary rapidly and widely. Short-term
Viruses
Ñ Since viruses are infectious sub-microscopic agents lacking an independent metabolism, they can only grow or reproduce within a living host cell and cannot multiply within the environment. Many viruses are host- specific, causing disease in humans or specific animals only. Rotaviruses and hepatitis A and E viruses are the most relevant water and excreta-related viruses.
Rotavirus unavailable in the developing world, and Hepatitis A and E viruses Rotavirus can infect people of all ages, the dehydration caused by rotavirus is a Hepatitis, a broad term for inflammation as well as many animals, however, in significant cause of mortality. A rotavirus of the liver, has a number of infectious humans its primary targets are infants, vaccine could prevent or reduce both the and non-infectious causes. Two of the the elderly, and people with compro- severity of rotavirus infection and many viruses that cause hepatitis (hepatitis A mised immune systems, as seen in deaths. and E) can be transmitted through water AIDS. Human rotaviruses are the most Viruses transmitted by the faecal-oral and food; hygiene is therefore important important single cause of infant death route have been detected in sewage, riv- in their control. Among the infectious in the world. Typically, 50 – 60 % of cas- ers, lakes, and treated drinking water. causes, hepatitis A and E are associated es of acute gastroenteritis of hospital- Human rotaviruses are excreted by pa- with inadequate water supplies and poor ised children throughout the world are tients in numbers up to 1011 per gram of sanitation and hygiene, leading to infec- caused by human rotaviruses. By the age faeces for periods of about 8 days. This tion and inflammation of the liver. The ill- of three, most children have been infect- implies that domestic sewage and any ness starts with an abrupt onset of fever, ed at least once by rotavirus, with a sig- environments polluted with the human body weakness, loss of appetite, nau- nificant number infected two or more faeces are likely to contain large num- sea, and abdominal discomfort, followed times. Although no natural immune state bers of human rotaviruses. Only 10 to by jaundice within a few days. The dis- exists for rotavirus, secondary infections 100 infectious virus particles are needed ease may range from mild (lasting 1 – 2 are usually less severe than primary in- to cause infection. This amount can read- weeks) to severe disabling disease (last- fections. The viruses infect cells in the ily be acquired through contact with con- ing several months). In areas highly en- villi of the small intestine, with disrup- taminated hands and objects. Although demic for hepatitis A, most infections oc- tion of sodium and glucose transport. ingestion of drinking water is not the cur during early childhood. The majority Acute infection has an abrupt onset of most common route of transmission, the of cases may not show any symptoms; severe watery diarrhoea with fever, ab- presence of human rotaviruses in drink- fatal cases due to fulminant acute hep- dominal pain and vomiting. Though eas- ing water constitutes a public health risk. atitis are rare. Nearly all patients recov- ily treated with intravenous fluids in de- (WHO, 2006, p. 257 and
Sandec Training Tool: Module 2 19 3 – Diseases
lated to one another, are both transmit- Dengue virus affecting mainly children. Early clinical ted via the faecal-oral route, most often Dengue is transmitted by the bite of an diagnosis and careful clinical manage- through contaminated water and from Aedes mosquito infected with any one of ment by experienced physicians and person to person. Both hepatitis A and E the four dengue viruses. It occurs in trop- nurses increase survival of patients. are found worldwide. Hepatitis A is par- ical and sub-tropical areas of the world. Aedes mosquitoes generally acquire ticularly frequent in countries with poor Symptoms appear 3 – 14 days after the the virus while feeding on the blood of sanitary and hygienic conditions. Coun- infective bite. Dengue fever is a febrile an infected person. After virus incuba- tries with economies in transition and illness that affects infants, young chil- tion for 8 – 10 days, an infected mosqui- some regions of industrialised countries dren and adults. Symptoms range from to is capable, during probing and blood with sub-standard sanitary conditions a mild fever, to incapacitating high fe- feeding, of transmitting the virus to sus- are also highly affected, e. g. in southern ver, with severe headache, pain behind ceptible individuals for the rest of its life. and eastern Europe and some parts of the eyes, muscle and joint pain, and rash. Infected female mosquitoes may also the Middle East. Outbreaks of hepatitis There are no specific antiviral medicines transmit the virus to their offspring via E have occurred in Algeria, Bangladesh, for dengue. It is important to maintain the eggs, but the role of this in sustain- China, Ethiopia, Indonesia, Iran, Liby- hydration. Dengue haemorrhagic fever ing transmission of virus to humans has an Arab Jamahiriya, Mexico, Myanmar, (fever, abdominal pain, vomiting, bleed- not yet been delineated. Nepal, Pakistan, Somalia, and the Cen- ing) is a potentially lethal complication, tral Asian Republics of the CIS. The mor- tality rate is low (0.2 % of icteric cases) and the disease ultimately resolves. Oc- Mosquito breeding sites casionally, extensive necrosis of the liver The mosquitoes are found indoors, in closets and other dark places. Outside, they rest where it is cool and shaded. The female mosquito lays her eggs in water containers in and around occurs during the first 6 – 8 weeks of ill- homes, schools and other areas in towns or villages. These eggs become adult in about 10 ness. In such cases, high fever, marked days. Dengue mosquitoes breed in exposed water storage containers. Favoured breeding abdominal pain, vomiting, jaundice, and places are: barrels, drums, jars, pots, buckets, flower vases, plant saucers, tanks, discard- hepatic encephalopathy (with coma and ed bottles, tins, tyres, water cooler etc., and a lot more places where rainwater collects or is seizures) are the signs of fulminant hep- stored. All efforts of control should be directed against the mosquitoes. It is important to take control measures to eliminate the mosquitoes and their breeding places. However, the efforts atitis, leading to death in 70 – 90 % should be intensified before the transmission season (during and after the rainy season) and of the patients. In these cases, mor- at the time of epidemics. tality is highly correlated with increas- The spread of dengue is attributed to expanding geographic distribution of the four dengue ing age, and survival is uncommon over viruses and their mosquito vectors, the most important of which is the predominantly ur- 50 years of age. Among patients with ban species Aedes aegypti. A rapid rise in urban populations is bringing increasing numbers chronic hepatitis B or C or underlying of people into contact with this vector, especially in areas favouring mosquito breeding, e. g. liver disease, who are super infected where household water storage is common and where solid waste disposal services are inadequate.
Figure 18: Body fluids containing different virus concentrations.
Sandec Training Tool: Module 2 20 3 – Diseases
Humans are the main amplifying host Dengue: Facts & figures of the virus, though studies have shown • The global prevalence of dengue has grown dramatically in recent decades. Before 1970, only nine countries had experienced dengue haemorrhagic fever (DHF) epidemics, a that in some parts of the world mon- number that had increased more than four-fold by 1995. keys may become infected and perhaps • Some 2500 million people – two fifths of the world’s population – are now at risk from den- serve as a source of virus for uninfect- gue. WHO currently estimates there may be 50 million cases of dengue infection world- ed mosquitoes. The virus circulates in wide every year. the blood of infected humans for two to • Not only is the number of cases increasing as the disease is spreading to new areas, but seven days, at approximately the same explosive outbreaks are occurring. In 2001, Brazil reported over 390 000 cases, including time as they have fever. Aedes mosqui- more than 670 cases of DHF. toes may acquire the virus when feed- • An estimated 500 000 cases of DHF require hospitalisation each year, a very large number ing on an individual during this period. of which are children. At least 2.5 % of cases die, although case fatality could be twice as
Bacteria
Ñ Bacteria are microorganisms a few micrometers in size and of varying shapes, such as spheres, rods or spirals. Unlike animal cells, they do not contain a nucleus (prokaryotes). Bacteria are ubiquitous: growing in soil, in the deep ocean or even in acidic hot springs. A gram of soil or a millilitre of water can contain several million bacterial cells. Though the vast majority is harmless or even beneficial to humans, a few can cause diseases, such as cholera, trachoma or salmonellosis.
Vibrio cholerae and is closely linked to inadequate en- mum requirements of clean water and Cholera is an acute diarrhoeal infection vironmental management. The absence sanitation are not met. Among people caused by ingestion of the bacterium or shortage of safe water and sufficient developing symptoms, 80 % of episodes Vibrio cholerae. Transmission occurs sanitation combined with a generally are of mild or moderate severity. Among through direct faecal-oral contamination poor environmental status are the main the remaining cases, 10 – 20 % devel- or via ingestion of contaminated water causes of spread of the disease. Typical op severe watery diarrhoea with signs and food. The disease is characterised in at-risk areas include peri-urban slums, of dehydration. If untreated, as many as its most severe form by a sudden onset where basic infrastructure is not availa- one in two people may die. With proper of acute watery diarrhoea that can lead ble, as well as camps for internally dis- treatment, the fatality rate should stay to death by severe dehydration and kid- placed people or refugees, where mini- below 1 %.
Sandec Training Tool: Module 2 21 3 – Diseases
Chlamydia trachomatis Trachoma is the result of infection of the eye with Chlamydia trachomatis. Infec- tion spreads from person to person, and is frequently passed from child to child and from child to mother, especially in areas of water shortage, numerous flies and crowded living conditions. Infection often begins during infancy or childhood and can become chronic. If left untreated, the infection eventual- ly causes the eyelid to turn inwards and the eyelashes to rub on the eyeball, re- sulting in intense pain and scarring of the front of the eye. This ultimately leads to irreversible blindness, typically between 30 and 40 years of age.
Trachoma: Facts & figures • 500 million people are at risk from Photo 10: Variable-sized flies on the face of a child infected by trachoma in Gambia. trachoma. (Source: Johnson, 2004, Fig. 17) • 146 million are threatened by blindness. • 6 million people are visually impaired by trachoma. Diarrhoea (can be caused by several viruses, bacteria or protozoa): Facts & figures • 1.8 million people die every year from diarrhoeal diseases (including cholera); 90 % are • The disease is strongly related to lack of children under five, mostly in developing countries. face washing often due to a lack of nearby safe water sources. • 88 % of diarrhoeal diseases are attributed to unsafe water supply, inadequate sanitation and hygiene. • Improving access to safe water sources and better hygiene practices can reduce trachoma morbidity by 27 %. (WHO, 2004)
Protozoa
Ñ Protozoa are one-celled eukaryotes (in contrast to prokaryotic cells, such as bacteria, eukaryotic cells contain a nucleus) about 10 – 50 micrometers in size. Many protozoa are parasitic, such as plasmodium (malaria), entamoeba histolytica (amoebiasis), and giardia lamblia (giardiasis), and can affect human health. Some protozoa have the ability to form a cyst to survive harsh conditions, such as exposure to extreme temperature, chemicals or long periods without water or food. In parasitic species, the cyst allows survival outside the host and transfer from one host to another.
Entamoeba histolytica Amoebiasis is caused by invasion of Person-to-person contact and contami- the protozoan parasite Entamoeba his- nation of food by infected food handlers tolytica in the intestinal wall. Amoebic appear to be the most significant means colitis results from ulcerating mucosal of transmission, although contaminated lesions caused by the release of parasite- water also plays a substantial role. Inges- derived hyaluronidases and proteases. tion of faecally contaminated water and Hepatic infection occurs as a conse- consumption of food crops irrigated with quence of entry of the parasite into contaminated water can both lead to the afferent bloodstream. The disease transmission of entamoeba histolytica. is prevalent throughout the developing Sexual transmission, particularly among nations of the tropics, at times reach- male homosexuals, has also been docu- ing a prevalence of 50 % of the general mented. (WHO, 2006, p. 266) population. It is estimated to cause more Photo 11: Photomicrograph of an Entamoeba histolytica. (Source:
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Helminths (parasitic worms)
Ñ Helminths are parasitic worms living inside their host. Intestinal helminths are those that live inside the digestive tract. Intestinal worm infection is the most common parasitic infection worldwide. About 500 mil- lion people in the South-East Asia Region are chronically infected with intestinal worms and all 11 countries in the Region are endemic. Infection rates differ according to ecology, however, in some communities, they are as high as 95 %. The infection predominantly occurs in school-age children.
Helminths are divided into: soil). After infective eggs are swallowed, • Trematodes (flukes). Adult flukes the larvae invade the intestinal mucosa are leaf-shaped flatworms. Prominent and are carried via the circulation to the oral and ventral suckers help maintain lungs. The larvae mature further in the position in situ. Flukes are hermaph- lungs, penetrate the alveolar walls, as- roditic except for blood flukes, which cend the bronchial tree to the throat and are bisexual. The life cycle includes are swallowed. Upon reaching the small a snail intermediate host. Chlonor- intestine, they develop into adult worms. chis, Fasciola, Opisthorchis and Para- Adult worms can live 1 – 2 years. Eggs gonimus are the main trematodes that in the soil can remain infective for sever- cause infection in humans. al months or years. (Cf. Fig. 19)
Ascariasis is an infection of the small in- 200 000 eggs per day, which are passed skin contact with infective third-stage testine caused by Ascaris lumbricoides, with the faeces. Unfertilised eggs larvae (L3) that have the ability to pene- a large roundworm. Children are infected may be ingested but are not infective. trate through the skin, frequently enter- more often than adults, the most com- Fertile eggs embryonate and become in- ing the body via the hands, feet, arms or mon age group being 3 – 8 years. The in- fective after 18 days to several weeks, legs. A. duodenale L3 can also be ingest- fection is likely to be more serious if nutri- depending on the environmental condi- ed. L3s migrate through the body and tion is poor. They often become infected tions (optimum: moist, warm, shaded enter the lungs from which they are ex- upon putting their hands to their mouths after playing in contaminated soil. Eating uncooked food grown in contaminated soil or irrigated with inadequately treat- ed wastewater is another frequent av- enue of infection. The first sign may be the passage of a live worm, usually in the faeces. In a severe infection, intesti- nal blockage may cause abdominal pain, particularly in children. People may also experience cough, wheezing and diffi- culty in breathing or fever. Ascariasis is found worldwide. Infection occurs with greatest frequency in tropical and sub- tropical regions, and in any areas with in- adequate sanitation. Worldwide, severe Ascaris infections cause approximately
60 000 deaths per year, mainly in chil- Photo 12: Photomicrograph of a hookworm larva. (Source:
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pelled by cough and swallowed into the it can be prevented by protecting water Schistosomiasis: Facts & figures intestine where they first moult twice to sources and filtering potentially contami- • An estimated 160 million people are become adults. Adult hookworms are nated water.
Intestinal helminths: Facts & figures • 133 million people suffer from high- intensity intestinal helminths infection often leading to severe consequences, such as cognitive impairment, massive Figure 20: Life cycle of schistosoma.
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3.3 What are the main chemical contaminants in drinking water?
Ñ In contrast to microbial contamination, chemicals arising in drinking water are usually of health concern only after extended exposure of years rather than months (with the exception of nitrate). Ñ Arsenic and fluoride are important geogenic contaminants of drinking water in developing countries, whereas nitrate and lead belong to the most relevant anthropogenic contaminants.
In contrast to the previously described substances that are discharged or leach highly dependent on the depth to which diseases related to microbiological con- intermittently to flowing surface wa- the well is sunk. tamination, the diseases caused by ters or groundwater supplies from con- Arsenic has not been demonstrated to chemicals in drinking water are non- taminated landfill sites for example. A be essential in humans. It is an important communicable. number of chemical contaminants have drinking water contaminant, as it is one Microbial hazards make the largest been shown to cause adverse health of the few substances known to cause contribution to waterborne disease in effects in humans as a consequence cancer in humans through consumption developed and developing countries. of prolonged exposure through drinking of drinking water. There is overwhelm- Nevertheless, chemicals in water sup- water. ing evidence from epidemiological stud- plies can cause serious health problems Significant problems even crises can ies that consumption of elevated lev- – whether the chemicals are naturally occur, however, when chemicals posing els of arsenic through drinking water is occurring or derive from sources of high health risks are widespread but their causally related to the development of pollution. At a global scale, fluoride and presence is unknown because their long- cancer at several sites, particularly skin, arsenic are the most significant chemi- term health effect is caused by chron- bladder and lung. In several parts of the cals, each affecting perhaps millions of ic exposure as opposed to acute expo- world, arsenic-induced disease, including people. However, many other chemicals, sure. This has been the case of arsenic cancer, is a significant public health such as selenium, nitrate and lead, can in groundwater in Bangladesh and West problem. (WHO, 2006, p. 306) be important contaminants of drinking Bengal, for example. For some contami- water under specific local conditions. nants, there will be exposure from sourc- Arsenic: Facts & figures (Thompson et al., 2007, p. vii) es other than drinking water, and this • In Bangladesh, between 28 and 35 mil- lion people consume drinking water with Most chemicals occurring in drink- may need to be taken into account when elevated levels of arsenic. ing water are of health concern only af- setting standards and considering the • The number of cases of skin lesion relat- ter extended exposure of years rather need for standards. Drinking water moni- ed to drinking water in Bangladesh is than months. The principal exception is toring strategies should therefore not be estimated at 1.5 million. nitrate. Typically, changes in water qual- considered in isolation from other poten- • Arsenic contamination of groundwater ity occur progressively, except for those tial routes of exposure to chemicals in has been found in many countries, in- the environment. (WHO, 2006, p. 145) cluding Argentina, Bangladesh, Chile, China, India, Mexico, Thailand, and the United States. Sources Examples Arsenic • Preventive measures comprise a Naturally occurring Rocks and soils, Arsenic is widely distributed throughout reduction in consumption of drinking chemicals (including cyanobacteria in the earth’s crust, most often as arsenic water with elevated levels of arsenic, by algal toxins) surface water. sulphide or as metal arsenates and arse- identifying alternative low arsenic Chemicals from Application of nides. Arsenicals are used commercial- water sources or by using arsenic agricultural manure, fertilisers ly and industrially, primarily as alloying removal systems. activities (including and pesticides, (WHO, 2004) pesticides) intensive animal pro- agents in the manufacture of transistors, duction practices. lasers and semiconductors. Arsenic is Chemicals from Sewage and waste introduced into drinking water sources, human settle- disposal, urban primarily through the dissolution of natu- ments (including runoff, fuel leakage. rally occurring minerals and ores. Except those used for pub- for individuals who are occupationally lic health purposes, exposed to arsenic, the most important e. g. vector control) route of exposure is through the oral Chemicals from Manufacturing, intake of food and beverages. There are a industrial activities processing and mining. number of regions where arsenic may be present in drinking water sources, partic- Chemicals from Water treatment water treatment and chemicals; corrosion ularly groundwater, at elevated concen- distribution of and leaching from trations. Arsenic in drinking water has a storage tanks and significant health effect in some areas, pipes. and is considered to be a high-priority Photo 14: Irrigation pumps discharging arsenic Table 9: Categorisation of chemical sources in substance for screening in drinking wa- contaminated groundwater to paddy fields. (Source: Roberts et al., 2007) drinking water. (Thompson et al., 2007, p. 6) ter sources. Concentrations are often
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Fluoride toothpaste. However, drinking water is ed, defluoridation may be the only solu- Ingestion of excess fluoride, most com- typically the most significant source. A tion (cf. defluoridation filters in Module monly in drinking water, can cause person’s diet, the general state of health 3). Mothers in affected areas should be fluorosis that affects the teeth and and the body’s ability to dispose of fluo- encouraged to breastfeed since breast bones. Moderate amounts lead to dental ride all affect how the exposure to fluo- milk is usually low in fluoride.
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30 January 2000: Cyanide spill in the Nitrate Microbial contamination can increase Danube – example of an accidental Nitrate and nitrite are naturally occurring the risk significantly. Methaemoglobi- chemical contamination ions that form part of the nitrogen cycle. naemia has rarely been associated with A dam breaks at the Aurul Mine Tailings Recovery Plant in north-western Romania, Nitrate is used mainly in inorganic fertilis- nitrate in the absence of faecal contam- releasing around 100 000 m3 of wastewa- ers. The nitrate concentration in ground- ination of the drinking water. (WHO, ter with a high concentration of cyanide water and surface water is normally low 2006, p. 196c) and heavy metals in the Danube through but can reach high levels as a result of The group at greatest risk is bottle-fed its tributaries. In view of the magnitude of leaching or runoff from agricultural land infants. Breastfeeding protects babies the ecological disaster and its potential im- pact on human health, the governments or contamination from human or animal from methaemoglobinaemia. Boiling wa- of Romania, Hungary and Yugoslavia, as waste as a consequence of the oxidation ter does not remove nitrate.
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4.1 How can we disrupt the transmission routes of pathogens?
Ñ Washing hands after defecation or constructing safe sanitation facilities are primary barriers that prevent pathogens from entering the environment. Ñ Washing hands before eating or protecting food from flies are secondary barriers that prevent pathogens from infecting a new host or contaminating food.
The most effective ways of reducing dis- idemiological studies, it seems reasona- ease transmission is to erect primary bar- ble to conclude that the hygiene practic- riers to prevent pathogens from entering es of prioritisation should be those that the environment. This can be done by: constitute the primary barriers to patho- • Washing hands with soap after defe- gen transmission. These practices pre- cation or after cleaning children’s bot- vent faecal material from entering the toms after their defecation. domestic environment of the susceptible • Constructing sanitation facilities to child. Human stools should be regarded prevent the spread of diseases by as the public enemy number one. (Curtis flies and contamination of drinking et al., 2000, p. 30) water, fields and floors. Interventions to establish primary and secondary barriers comprise “hardware” Where sanitation facilities are badly Figure 21: Barriers and interventions to disrupt approaches, such as water supply and planned and constructed, poorly main- transmission of diseases. (Adapted from sanitation facilities and services, as well WHO, 2005, p. 10). tained, used wrongly or not used at all, as “software” approaches of hygiene their construction can set up further behaviour. Cf. Modules 3 – 7 for de- potential disease transmission routes, tails about the approaches related to wa- and lead to contamination of the envi- • Households (both formal and ter treatment, sanitation, excreta, fae- ronment. Selection of the right tech- informal). cal sludge or solid waste management, nologies, good design, appropriate use • Schools. and the planning approaches. Motivation and proper management are required • Semi-public places (such as and implementation of hygiene promo- to protect against these additional risks. hospitals). tion are described in this Module. (WHO, 2005, p. 10) • Public places (such as markets, bus An additional approach to reducing Primary interventions with the great- stations etc). the burden of diseases is the preventive est impact on health often relate to the • Refugee communities. use of vaccines and disease-treatment management of faeces at the house- with pharmaceutical drugs. This does hold level. This is because (a) a large per- Sanitation and hygiene promotion would not only protect the individual person centage of hygiene-related activity takes also have to be geared up in many cases from illness, but can also help to inter- place in or close to the home and (b) to handle “emergency” situations. Such rupt the transmission route of diseases first steps to improving hygienic practic- emergencies could relate to the outbreak and thus benefit the entire community es are often easiest to implement at the of epidemic diseases (such as cholera) (despite the risk of pathogens becoming household level. However, to achieve full or to a physical event such as a hurricane resistant to the drugs). health benefits and in the interest of hu- or earthquake. (WHO, 2005, p. 10) man dignity, other sources of contami- Secondary barriers are hygiene prac- nation and disease also need to be man- tices preventing faecal pathogens, which aged, such as: have entered the environment via stools Further questions • Sullage (dirty water that has been or on hands, from multiplying and reach- Ñ Engineers building water treatment and used for washing people, clothes, ing new hosts. Secondary barriers thus sanitation facilities need to understand all pots, pans etc). include washing hands before prepar- the transmission routes: Building a septic • Drainage (natural water that falls as ing food or eating, and preparing, cook- tank without air-ventilation does not solve rain or snow). ing, storing, and re-heating food in such the problem of fly transmission. How re- alistic is implementation of the required • Solid waste (also called garbage, a way as to avoid pathogen survival and interdisciplinary approach? refuse or rubbish). multiplication. They also include protect- ing water supplies from faecal contam- Additional info All these sources of contamination must inants and water treatments, such as Ñ Curtis, Cairncross et al. (2000): “Review: be managed in all the locations where boiling or chlorination. Other second- Domestic hygiene and diarrhoea – pin- they are generated. ary barriers include keeping playgrounds pointing the problem.” Tropical Medicine Thus, a full-scale programme to free from faecal material, preventing & International Health 5(1): 22-32. www3. improve hygiene would need to address children from eating earth and controlling interscience.wiley.com/journal/119190686/ abstract (last accessed 16.07.08) the management of excreta, sullage, flies. (Curtis et al., 2000, p. 25) Download available on the CD of Sandec’s drainage, and solid waste at the follow- By combining the biological reasoning Training Tool and from the Internet. ing levels: of the F Diagram and the findings of ep-
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4.2 Why is hygiene promotion important and what are the challenges of hygiene approaches?
Ñ “Hardware” approaches such as water treatment, sanitation facilities and equipment alone are not efficient enough to disrupt the transmission routes of diseases. It is imperative for them to be accompanied by “software” approaches, such as the promotion of hygiene behaviour. Ñ Hygiene behaviour may also serve needs other than only health improvements, such as the desire to create order and beauty and to show respect for ethical issues. Ñ Some of the challenges of hygiene approaches include frequent confusion of “good hygiene” (in the moral sense) and “safe hygiene” (in the epidemiological sense), the lack of resources and time, and the fact that hardware approaches are often inappropriate because they were not planned within an overall “hygiene improvement” framework.
Hygiene improvements can lead to a construction of physical infrastructure, 45 % reduction in diarrhoeal disease mor- which may be a secondary, more long- bidity (cf. Chapter 2.2). Both research er-term strategy. Furthermore, hygiene and field experience has shown that promotion should be seen as a major el- “hardware” approaches alone typically ement in the programme, requiring not have little or no health impact. Access to only adequate financial resources, but water and sanitation must be accompa- also the required levels of profession- nied by “software” approaches. Health al expertise and effort. Too often, engi- benefits from water and sanitation pro- neers may seek to “add on” a hygiene grammes will not be fully realised un- promotion component to what is essen- less hygiene behaviour is promoted and tially a latrine construction programme, achieved. Correct use of the hardware without due attention to the complexi- results in the greatest health impact. ties of making hygiene promotion effec- (Heeb et al., 2007, Module 4-5) tive. An important factor, often neglected during the planning phase, is the need to Challenges of hygiene approaches pay sufficient attention to collecting the However, since hygiene approaches are types of information required to design not easily implemented, as they pose Photo 17: Washing hands with water and really effective strategies of behaviour- several challenges, a sophisticated and soap. (Source: Eawag/Sandec) al change. At the other end of the scale, well-imbedded hygiene promotion is insufficient time may be made available important. glected or marginalised in programmes for the needed change in behaviour to Hygiene is a complex and confusing aiming at improving hygiene; many of take root. Changing hygienic practices subject. Whilst hygienic practices play a these programmes place much greater is often a long-term process, which may fundamental role in the prevention of in- emphasis on the construction of hard- not be achieved for example within the fectious diseases, they also serve other ware (often prioritising water supply over three-year planning horizon of a conven- needs. Amongst these is the desire to sanitation). This not only means that tional water supply project, or indeed the create order and beauty and to show re- there is insufficient resources available common term of a local political adminis- spect for traditional values. Those who for effective hygiene promotion, but it tration. (WHO, 2005, p. 70) seek to promote safe hygiene need to also means that the hardware installed both understand the motivations under- may be inappropriate because it is not Further questions Ñ If hygiene approaches are so effective, lying hygiene behaviour in general and be planned within an overall “hygiene im- can investments in other aspects (e. g. able to identify specific practices that may provement” framework. In some cas- sanitation, immunisation etc.) be reduced? be putting health at risk. Whilst hygiene es, these interventions may even make Ñ Are infrastructural interventions com- promotion is increasingly favoured by it more difficult for communities and bined with hygiene measures more costly? policy-makers because of its potential to households to improve hygiene and en- Ñ Traditionally, engineers are not educated deliver reductions in diarrhoeal diseases joy real health benefits. This may hap- in health issues. How can this be rectified? at low cost, such interventions are often pen for example when designs are inap- Should “hygiene promotion” be a subject at technical schools? ‘foggily formulated’. ‘Good’ hygiene, in propriate and facilities cannot be used, the moral sense, is confused with ‘safe’ or where sections of the community are Additional info hygiene in the epidemiological sense. excluded. To be effective, sanitation and Ñ WHO (2005): Sanitation and hygiene (Curtis et al., 2000, p. 22) hygiene promotion programmes need promotion. Programming guidance. Gene- Changing hygiene behaviour is a key to be designed with the hygiene im- va, WHO. www.who.int/water_sanitation_ element and may often be the most cru- provement framework in mind – ensuring health/hygiene/sanitpromotionguide/en/in- dex.html (last accessed 16.07.08) cial step in achieving health gains. Hy- adequate resources for all three ele- Download available on the CD of Sandec’s giene promotion is all about changing ments, and perhaps in some cases, fo- Training Tool and from the Internet. behaviour. Nevertheless, it is often ne- cusing on hygiene promotion ahead of
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4.3 How to make sure that hygiene promotion works?
Ñ Choices have to be made about the behaviours to target. Too many messages can be confusing and counterproductive. Ñ Furthermore, hygiene promotion should build on what exists, target a specific audience, identify the motives for behavioural change, and communicate positive messages.
Changing people’s behaviour is a diffi- lic health resources. Practitioners cannot • Target a small number of risk cult and uncertain process. Programmes opt out of making a considered diagnosis practices: The priorities for hygiene have to focus their efforts on a small of the one or two practices most likely to behavioural change are likely to in- number of messages of proven public be sources of risk. This needs to be done clude hand-washing with soap (or a health importance if they are to avoid in the light of the biological and epidemi- local substitute) after contact with ex- wasting the resources of both the pro- ological evidence and on the basis of a creta, and the safe disposal of adults’ grammes and target communities. Pub- careful diagnosis of behaviour. (Curtis et and children’s excreta. Other exam- lic health planners thus have to make al., 2000, p. 30) ples of hygiene behaviour are shown hard choices concerning the promotion Much has been learned about making in figure 22. of specific hygiene practices. Logically, hygiene promotion effective. The main • Target specific audiences: Audienc- these should reflect the particular prac- ideas are summarised below: es may include mothers, children, old- tices with the greatest health risk. It is • Build on what exists: A hygiene pro- er siblings, fathers, opinion leaders or usually not feasible or desirable to car- motion programme should be based other groups. An important group are ry out full-scale risk factor studies be- on a thorough understanding of: those primarily involved with child- fore designing an intervention. Hence, – The most important risk practices care. Audiences need to be identified decisions have to be made in the light to be targeted. in each particular case. of what is known about the interaction – Who are primary/secondary and ter- • Identify the motives for behaviour- between human behaviour and the be- tiary audiences for key messages. al change: These may have nothing haviour of pathogens. (Curtis et al., – Who can most effectively motivate to do with health. People may be per- 2000, p. 22) behavioural change. suaded to wash their hands in order Hygiene promotion programmes are – What may prevent behavioural for their neighbours to respect them, to be clearly formulated and visibly effec- change. for their hands to smell nice or for tive; hard choices have to be made about – How can audiences be most effec- other reasons. Participatory planning the behaviours to target. Employing too tively reached. with target groups can be used to dis- many messages confuses and exhausts – How can the effectiveness of the cover local views about disease and the attention and goodwill of target pop- programme be measured. ideas about the benefits of safer hy- ulations, and thus wastes precious pub- giene practices. This can form the ba- sis for a hygiene promotion strategy. • Hygiene messages need to be positive: People learn best when they laugh, and will listen for a long- er time if they are entertained. Pro- grammes attempting to frighten au- diences will probably alienate them. Furthermore, messages consisting of “dos” and “don’ts” can be frustrat- ing and demoralising for the poor, par- ticularly where they urge unrealistic actions for poor families. (WHO, 2005, p. 70)
Photo 18: Children in Karnataka, India, playing with water. (Source: Marcel Kessler)
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Always wash hands A hygiene promotion programme tailored to local customs in Bobo-Dioulasso, before and after us- Burkina Faso ing the toilet and be- In Burkina Faso, the previous diarrhoeal prevention programmes focused on promoting oral fore handling food. Use rehydration therapy and improving water supplies. Yet, diarrhoea still causes as much child- clean water and soap hood illness and death in urban areas as malaria and respiratory tract infections. Hygiene if available. If not, use promotion programmes could have a major impact but will fail if they are not based on up-to- clean sand or ash. date local information. Small-scale and carefully focused research can increase the effective- ness of hygiene promotion programmes and optimise the use of scarce resources. A study revealed the following in Bobo-Dioulasso, Burkina Faso’s second largest city: Use a toilet. This puts • Unsafe stool disposal and inadequate hand-washing are the most widespread risk factors germs and worms out for childhood diarrhoea. of contact with peo- • The target audiences for promotion programmes should be mothers and older children ple. If there is no toilet, caring for infants under 3 and school-age children. it is best to defecate far from sources of water, • As local women do not associate poor hygiene with diarrhoea, the social virtue of in a place where faeces cleanliness is more likely to motivate behavioural change. School children may respond to will not be touched by peer pressure. people or animals. Cover • The best channels of communication are word-of-mouth, social gatherings, local radio, and it with dirt to keep flies theatre. Due to illiteracy, print-media are not suitable. away. Researchers from the London School of Hygiene and Tropical Medicine and from the Pro- gramme Saniya, Burkina Faso, have developed a large 3-year hygiene promotion programme to reduce childhood diarrhoea in Bobo-Dioulasso. It was tailored to local customs, built on Keep animals away existing motivation for hygiene and used locally appropriate channels of communication. from household food Drawing on this experience, they have produced a toolkit to help programme planners design and community water locally relevant hygiene interventions.
Use clean and safe methods of preparing and storing food. Wash fruits and vegetables or cook them well before eating them. Feed food scraps to animals or put them in a compost pile or toilet. Keep dishes clean after using them.
Protect water sources and use clean water for drinking and washing.
Photo 19: Hygiene workshop in Yunnan province, China. (Source: Eawag/Sandec)
Make fly-traps and Further questions cover food. This can Ñ Don’t people in developing countries have their own, culturally individual hygiene behav- prevent flies from iour? Don’t people feel patronised and restricted in their independence if told how to behave? spreading germs. Toilets Ñ Hygiene workshops and implementation of hygiene behaviour can be very time-consuming. that control flies or stop How is this time investment compensated? them from breeding can help. A fly-trap can be Ñ Who should be conducting hygiene promotion in the villages – outsiders or locals? Whose easily made of a plastic teaching is more effective? bottle: Cut the top part off the bottle, put some Additional info sweet bait, like sug- Ñ Appleton and Sijbesma (2005): Hygiene promotion. Thematic overview paper 1. Delft, IRC. ar or fruit, in the bottle www.irc.nl/content/download/23457/267837/file/TOP1_HygPromo_05.pdf (Iast accessed and put the top back in 16.07.08) the bottle upside-down. Ñ Conant (2005): Sanitation and Cleanliness for a healthy environment. Berkeley, Hesperian Flies will fly in but will Foundation. www.hesperian.info/assets/environmental/EHB_Sanitation_EN_lowres.pdf (Iast not be able to fly out. accessed 16.07.08) Ñ Conant and Fadem (2008): A Community Guide to Environmental Health. Berkeley, Hespe- Figure 22: Some examples of hygiene rian Foundation. www.hesperian.info/assets/EHB/EnviroBook4DL.pdf (Iast accessed 16.07.08) behaviour to prevent the spread of pathogens. Download available on the CD of Sandec’s Training Tool and from the Internet. (Conant, 2005, p. 8)
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4.4 Why is it important to monitor and evaluate hygiene promotion programmes?
Ñ Monitoring at the local level is absolutely necessary to ensure that the hygiene inputs are delivered and the expected outcomes attained. Ñ Evaluation provides a more systematic assessment of whether visions and objectives are being met in the long run and in the most effective manner possible.
Generally, monitoring observes a situ- ation for any changes that may occur over time, using one or more appropriate measuring device. Evaluation in contrast is the systematic determination of the merit and significance of something. It is essential to monitor key results (ideally improved health) to ensure that public investments result in public benefits. However, monitoring long-term health trends is difficult and can proba- bly only be the subject of periodic eval- uations. Instead, it is often more practi- cal to measure service coverage, use of facilities and hygiene behaviour. (WHO, 2005, p. 57). Monitoring systems provide a rapid and continuous assessment of what is happening. Monitoring is prima- rily needed at the project level to show whether: Photo 20: Monitoring of a mapping exercise with children in Ethiopia. (Source: Kar, 2008) • Inputs (investments, activities, deci- sions) are being made as planned. • Inputs are leading to expected outputs Evaluation of a hygiene promotion programme in Kerala, India (latrines built, behavioural change). After conclusion of a hygiene promotion intervention in Kerala, researchers studied the • Inputs are being made within the sustainability of behavioural change. They used various methods, including a questionnaire to agreed vision and rules. assess knowledge, spot observation, demonstration of skills on request, and household pocket voting to measure the hygiene outcome. Hence, the researchers evaluated the impact of the different intervention components on women, men, girls and boys two to nine years Evaluation provides a more systematic after the programme had ended. They also assessed the extent of the programme’s long- assessment of whether visions and ob- term changes in the use of newly installed toilets and hand-washing behaviour. jectives are being met in the long run and The results of the study can be summarised as follows: in the most effective manner possible. • The programme’s interventions led to a change in hygiene behaviour, which was sustained (WHO, 2005, p. 56) over time. • More than half of the adults reported good hand-washing practices, compared to less than Further questions 10 percent in a control area. Ñ Hygiene promotion programmes are often implemented within a specific frame- • The practice of hand-washing was not significantly associated with the passage of time work along with technical water and sani- since the interventions – up to nine years in some communities – thus indicating that tation improvements. In many cases, it is behavioural change had taken place and persisted. ethically unjustifiable to conduct “real ex- • Women recalled taking part in health education classes and this was significantly associat- periments”, i. e. experiments with a test or ed with good hand-washing practice, indicating that the classes are an effective part of the control group. How can the health effect of intervention. hygiene promotion alone be evaluated? • The effect of home visits and an awareness campaign on hygiene behaviour were not as Ñ What objectives other than improved significant, however, the home visits had an impact on knowledge. health does hygiene promotion have? • Analysis of the impact of interventions on men’s hand-washing suggests that this occurred indirectly, as most men did not attend the education sessions on health and hygiene or on maintenance and use of toilets. Additional info Ñ WHO (2005): Sanitation and hygiene The report suggests that changes in hygiene behaviour may persist indefinitely as a result of promotion. Programming guidance. Gene- such interventions. This implies that interventions promoting good hygiene are more cost- va, WHO. www.who.int/water_sanitation_ effective than previously accepted, since their benefits may persist for years to come. How- health/hygiene/sanitpromotionguide/en/in- ever, for changes in hygiene behaviour to be fully effective, the study also recommends that dex.html. (last accessed 16.07.08) the interventions should target also men directly and not only women.
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4.5 What further aspects of hygiene approaches have to be considered?
Ñ An enabling environment is imperative for effective hygiene promotion: Well-organised communities, insti- tutions and organisations are needed. Ñ Hygiene promotion is a very cost-effective intervention. Ñ There are often many more concrete and powerful incentives for water, sanitation and hygiene improvements than the promise of better health, e. g. time saved, increased social status, convenience, esteem or financial gain.
To ensure that hygiene approaches are im- practices and conditions in their commu- In addition to direct hygiene and health- plemented and effective along with hard- nities. In community-managed hygiene related objectives, there may also be wid- ware and hygiene promotion, political, promotion programmes, a representative er developmental objectives: strengthen socio-cultural and economic aspects also local organisation manages the planning the sense of community and community have to be considered. The so-called Hy- and implementation of local hygiene pro- action, increase the analytical, manageri- giene Improvement Framework is a use- motion activities. The programme may al and problem solving capacities of com- ful conceptual model for planning and im- have a range of objectives: munity members, reduce inequalities plementing water and sanitation projects • Immediate: to mobilise communi- between genders and social and eco- (cf. Figure 23). The three components, ty resources and build capacities to nomic groups, enhance self-confidence i. e. access to hardware, hygiene promo- identify and measurably reduce risky and self-respect of various groups, in- tion and enabling environment, are all conditions and practices, as well as cluding those that are disadvantaged or appropriate. Health and hygiene efforts strengthen positive ones of people’s marginalised. can have positive results even if not ac- own choice. Community-managed hygiene promo- companied by hardware interventions in • Longer-term: to reach and maintain tion programmes are best undertaken sanitation and water provision. However, a level of hygiene acceptable to the with relatively well-organised commu- an integrated programme with all three women and men of the community, nities with active leaders and their own components would be ideal. (Appleton which prevents or significantly reduc- resources. The communities need not et al., 2005, p. 13) es the previously existing risks of dis- be homogeneous and well off, but uni- ease transmission. ty and solidarity have to be sufficiently Political and institutional aspects • Ultimate: to empower communities strong. Otherwise, interested communi- Governments and others concerned with to solve their own hygiene problems ties may first need to demonstrate that inadequate hygiene may also want to de- and reduce the local incidence of and they can form active organisations and velop the capacities of local governments mortality from water and sanitation- effectively manage some form of local- and groups to plan and manage their own related diseases. ly initiated change. A ‘community’ may action programmes for improved hygiene vary from a single neighbourhood or vil- lage to administrative clusters, covering • Water supply systems • Communication a number of distinct settlements. In the Access to Hygiene • Improved sanitation • Social mobilization latter case, there are often two organisa- Hardware Promotion facilities • Community participation tional layers: • Household technologies • Social marketing • The organisation at the neighbourhood and materials • Advocacy or village level organises the partici- – Soap patory planning, implementation and – Safe water containers monitoring. – Effective water treat- ment • The organisation at the overall com- munity level manages the overall pro- gramme, dealing with such aspects as aggregation or co-ordination of Hygiene lower level plans, contracting and pro- Diarrheal Disease Prevention curement, financial management, and accounting for their work to the con- tributing male and female heads of • Policy improvement Enabling households. Environment • Institutional strengtening • Community organization Community organisations that manage • Financing and cost local hygiene promotion must represent recovery the different interest groups and capa- • Crosssector & PP partner- bilities in their neighbourhood, village ships or larger settlement. Typically, mem- Figure 23: The hygiene improvement framework. (WHO, 2005, p. 14) bers are women and men from the dif-
Sandec Training Tool: Module 2 33 4 – Hygiene Approaches
ferent socio-economic, ethnic and re- Is hygiene promotion cost-effective? A case study from Burkina Faso ligious sections with a good range in Researchers from the London School of Hygiene and Tropical Medicine and the Burkina Faso Ministry of Health investigated the cost-effectiveness of the Saniya hygiene promotion ages and skills. The groups to which they programme in Bobo-Dioulasso (the programme is described in chapter 4.3). They conducted a belong choose them for their commit- cost-effectiveness analysis to assess the efficiency and affordability of the intervention ment, trust, time, and relevant expertise relative to the status quo and obtained the following results: (traditional and modern) in health and • The total provider costs, including startup and three years running costs, amounted to hygiene. US$ 302 507. Should organisations for locally man- • Core programme activities (house-to-house visits, participatory discussions in health aged improvements include political centres, hygiene promotion in schools, street theatre, and radio broadcasts) accounted for leaders and government functionaries? only 31 % of the costs, while administration consumed 40 %. The latter can be of great help but can • Salaries represented 47 % of the total costs, communication 10 %, equipment 7 %, and also dominate decisions and monopo- transport 7 %. lise benefits. The solution depends on • The total costs for the 7286 households revealing behavioural change during the three-year programme in terms of soap and water amounted to US$ 160 125 (US$ 7.3 per year and local conditions. They may be respected household). and represent the interests of all. Other- • The programme averted an estimated 8636 cases of diarrhoea, 864 outpatient consulta- wise, some kind of checks and balance is tions, 324 hospital referrals, and 105 deaths. needed. Political leaders and functionar- • Savings to the provider from reduced treatment costs were estimated at US$ 10 716 and ies have sometimes also become ex-of- the corresponding savings to households were US$ 9136. This gives a total saving to soci- ficio members, or the organisation that ety of US$ 19 852, which rises to US$ 393 967 if indirect savings of caregiver time and lost manages the hygiene improvements is a productivity associated with child death are included. sub-committee with its own status and • The provider costs per case of diarrhoea averted totalled US$ 33.8. The cost to society was authority under a local government body. US$ 51.3, plummeting to US$ 7.9 if indirect savings are included. (Appleton et al., 2005, p. 23) The researchers concluded that hygiene promotion reduces childhood diarrhoea in Burkina Faso to less than one per cent of government health spending and to less than two per cent of household budgets. They also point out that: Financial and economic aspects • Replicating the programme elsewhere would involve less research and startup investment, As regards the economic aspects of reducing provider costs to US$ 26.9 per case of diarrhoea averted. hygiene approaches, both the costs of • The programme will be more cost-effective in areas with a higher incidence of childhood di- hygiene promotion and the benefits of arrhoea, which may offset the increased transport and communication costs of the the approach have to be taken into con- programme in rural areas. sideration. Cost-effective is regarded • Acceptability of this cost-effectiveness ratio in other settings will depend on resource as something economical based on the constraints and available budget.
Sandec Training Tool: Module 2 34 4 – Hygiene Approaches
There are many more concrete and Zimbabwe’s community health clubs create demand for better hygiene and sanitation therefore more powerful incentives for In rural Zimbabwe, community health clubs (CHCs) have been set up to change health behaviour and increase demand for better sanitation. A study of the clubs’ impact suggests water, sanitation and hygiene improve- that they have helped to change up to 17 key hygiene practices. This approach could now be ments than the promise of better health. replicated in other countries. Researchers at the London School of Hygiene and Tropical These incentives differ for different Medicine report from rural Zimbabwe where a model of community mobilisation is working to groups: change hygiene and sanitation practices. • Women and children appreciate less The project began in 1995 in the form of a pilot study and has since led to the creation of hun- hardship and more time for rest, play dreds of CHCs across rural Zimbabwe. The CHCs are voluntary groups led by local health (children) and schooling. technicians. CHCs aim to improve health and sanitation in villages by providing information and group support through weekly meetings. The study reports on the results of this ap- • Men sometimes discount such ben- proach in two rural districts with more than 13 000 CHC members. The researchers found efits on the basis that there is no that: need for schooling of women and girls • The CHCs were very popular and increased the sense of unity within communities. and idleness breeds laziness. Income- Participants felt a sense of achievement from improving their hygiene practices through the generating potential and peer pres- clubs. sure are more important incentives • Women were more prominent in CHCs in communities where men were absent. Participa- for the men. tion in the clubs increased women’s confidence and social standing in their communities. • Among those in the higher socio-eco- • Many families who attended the clubs improved their sanitation practices, including the nomic group, in lower groups climbing correct methods of hand-washing with soap. Families who had no access to latrines began to practise faecal burial. up or aspiring to do so and in groups • Levels of demand for sanitation and latrines increased substantially in the population. As a with urban contact, increased social result, 47 % of the population in the areas with functioning CHCs had access to latrines as status and following opinion leaders compared to 2 % in the non-CHC control area. and trends are important motivating In sum, the study found that CHCs were an effective way to improve the sanitation and factors. hygiene practices in poor rural areas because they create a culture of cleanliness among a • Willingness to pay for improved sani- population. It also showed that a strong community structure may help improve sanitation and tation is much higher in densely pop- hygiene behaviour.
Sandec Training Tool: Module 2 35 5 – References and Links
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Sandec Training Tool: Module 2 36 5 – References and Links
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