Global Issues in Water, Sanitation, and Health Workshop Summary (2009) / Chapter Skim
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Workshop Overview
Workshop Overview
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Worldwide, over one billion people lack access to an adequate water supply; more than twice as many lack basic sanitation (WHO/UNICEF, 2006)
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Lack of these necessities also establishes a vicious cycle, for poverty bars many in the developing world from obtaining the safe drinking water and sanitation needed to drive sustainable community growth and development. Recognizing that water availability, water quality, and sanitation are fundamental issues underlying infectious disease emergence, the Forum on Microbial Threats of the Institute of Medicine held a two-day public workshop in W ashington, DC, on September 23 and 24, 2008.
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. and sanitation infrastructure so as to reduce the risk of water-related infectious disease. Some topics important to water quality and health were either not covered at the workshop, covered only in passing, or were explored in greater detail in other National Research Council (NRC)
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The documentary explores the growing global water crisis and its staggering toll of some 14,000 "quiet preventable deaths" per day. Focusing on China, the Middle East, Africa, India, and the United States, Running Dry presents compelling argu See Davies in IOM (2009)
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with permission from the Ministry of Health and Family Welfare, Government of India. ments for international cooperation on water issues and highlights some promising grassroots programs to improve access to safe water (see Chapter 1)
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Water and Health in Africa Africa poses particular challenges to providing safe, accessible water for its rapidly growing population. Although the continent, particularly in the Congo Basin, possesses abundant water resources, the majority of Africans lack access to safe water, primarily as a consequence of poverty and armed conflicts (UNICEF, 10 For more information on this treaty, please see http://www.usbr.gov/lc/region/g1000/pdfiles/mextrety.pdf.
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and United Nations Children's Fund (UNICEF) Joint Monitoring Programme for Water Supply and Sanitation (JMP)
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Working with the Amhara Regional Health Bureau, and with local Lions Clubs, the Carter Center mobilized residents to build latrines. "There came to be a competition between villages, between families, in who could build the better latrine or the faster latrine," he recalled, with much of the momentum provided by women.
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. Interventions included preventive health education and instruction in the use of cloth filters to remove copepods from drinking water; preventing contamination of surface water by 15 Dracunculiasis, or Guinea worm disease, is the only infectious disease that is caused exclusively by ingestion of contaminated drinking water.
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SOURCE: Courtesy of The Carter Center.
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On water and sanitation specifically, the MDGs aim to halve the proportion of people without sustainable access to safe drinking water and basic sanitation. Basic sanitation is defined as access to, and use of, excreta and sullage*
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. There are two main challenges to achieving the MDG's drinking water and Figure WO-5 sanitation target: the rapid pace of urbanization requires a major effort to maintain R01515 the current coverage levels and a huge number of rural people do not have basic sanitation and safe drinking water, which calls for an intensive mobilization of r now vector, editable esources to reduce the vast gap in coverage between urban and rural populations (WHO/UNICEF, 2006)
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SOURCE: Courtesy of The Carter Center.
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Despite the overall success of the dracunculiasis eradication campaign, some countries, including Ghana, continue to report thousands of cases per year, H opkins reported. The highest rates of disease occur in the impoverished north of that country, where access to safe water is extremely limited due to scarce rainfall and geology that makes well-drilling difficult.
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Changes in water flow or quality, which can influence the population dynamics of vector species that transmit infectious diseases and intermediate hosts for microbial pathogens, also influence the prevalence and transmission dynamics of infectious diseases. Workshop presentations demonstrated how an analysis of transmission processes guides disease prevention efforts, and how such analyses may reveal the importance of the household as a target for clean water interventions.
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. They described four key categories of disease transmission processes:17 • Water-borne: The pathogen is acquired through consumption of con taminated water, as occurs in diarrheal diseases, dysenteries and typhoid fever.
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Waterborne Diseases Waterborne diseases may result when pathogenic organisms including but not limited to viruses (hepatitis A and hepatitis E) , parasites (e.g., giardia, crypto sporidium)
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. In the second, he recommended the analysis of disease control on multiple spatial scales using geographical information systems, based on his observation that effective interventions to address water- and sanitation-related infectious diseases are often
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For entry: or = oral; pc = percutaneous or through mucosa; for egress: fe = in feces; pa = perianal region; ur = in urine. SOURCE: David Bradley.
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The authors concluded, therefore, that policies that aim to improve water quality at the source may be compromised unless they are accompanied by corresponding measures to ensure safe household water storage and treatment. The profound disease burden attributed to diarrhea makes it the most important target for waterborne disease prevention, Clasen said.
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. Following a systematic review of intervention trials to improve water quality, Clasen and his coauthors concluded that household-based interventions were nearly twice as effective as source-based measures for preventing diarrheal disease (Clasen et al., 2007b)
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. Tauxe observed that in addition to providing measurable protection against diarrheal diseases, safe water programs can serve as a springboard for additional public health interventions to tackle water-related infectious diseases.
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Water quality was poor throughout the country and especially in rural areas, where sanitation coverage reached only about one in five people. As the number of cases mounted, epidemiological investigations revealed a number of underlying risk factors for infection, all of which would be expected to raise the risk of water- or foodborne infections via the fecal-oral route: having a family member with diarrhea, consuming water and food from street vendors, and being unemployed (a marker for poverty)
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Instituto de Medicina Tropical Alexander von Humboldt; Lima,as WO-10 Rev 2-6 same Peru. Universidad Mayor de San Simón, Cochababmba, Bolivia.
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According to the CDC, a total of 36 waterborne disease outbreaks were reported in 19 states between 2003 and 2004; 30 of these outbreaks were 23 For a detailed discussion of the ecological basis of cholera epidemiology, see the recent Forum workshop summary, Global Climate Change and Extreme Weather Events: Understanding the Contributions to Infectious Disease Emergence (IOM, 2008)
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Among the lessons learned from this harrowing experience, Davis noted • The importance of stringent water quality standards, and in particular that turbidity is more than an aesthetic property of finished water; • The demand for advances in water sampling that maximize safety and minimize response time; • The necessity of good public health surveillance for determining the scope, source, and progress of an outbreak; 24 Following a minimal infective dose of approximately 130 cryptosporidium oocysts, humans excrete billions of oocysts per day in their stools and continue to do so after disease symptoms resolve.
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. • The need for communication between public health and water authority agencies to prevent and address waterborne disease outbreaks; and • The critical role of the media in disseminating public health messages.
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28 GLOBAL ISSUES IN WATER, SANITATION, AND HEALTH E coli O157:H7 and Campylobacter, Walkerton, Ontario, 2000 Bacterial contamination of the water supply in Walkerton, Ontario, in the spring of 2000 sickened nearly half of the town's 5,000 residents and caused 7 deaths, as well as 27 cases of hemolytic uremic syndrome, a serious kidney disease with potential lifelong complications (Hrudey and Walker, 2005)
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Deficiencies in the water distribution system, according to Beach, are estimated to account for between 13 and 17 percent of all U.S. waterborne disease outbreaks.
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Today, this pathogen is increasingly linked to community-wide outbreaks that stem from inadequate chlorination in individual swimming pools. The measurable reduction in waterborne disease outbreaks in the United States over the past 30 years attests to the effectiveness of water quality regulations to improve public health, Beach concluded.
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. As was previously noted, similar heavy precipitation events preceded major waterborne disease outbreaks in both Milwaukee, Wisconsin (see Davis et al.
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The investigators also identified several types of culturable viruses. Reynolds advocated more extensive real-time monitoring in order to survey exposure to waterborne disease, as well as long-term analyses to determine exposure levels for different populations.
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Risk Assessment Estimates of the true impact of waterborne disease vary widely because they rely on extrapolations of exposure, rather than on surveillance based on accurate monitoring and testing of pathogens in the water supply, Reynolds observed. She noted that risk assessments for water-related diseases are also hampered by the dearth of epidemiological data on pathogen infectivity rates and dose responses, particularly in vulnerable populations such as infants, immunocompromised individuals, and the elderly.
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Singer also discussed the parameters and limitations of various approaches to water treatment, emphasizing the significant barriers to disinfection posed by particulate matter and describing different methods and approaches for its removal by filtration and flocculation.26 Effectiveness and cost-effectiveness Based on a systematic review of intervention trials to improve microbiological water quality levels at both source (dug wells, boreholes, or stand posts) and point of use (improved storage, chlorination, solar disinfection, filtration, or combined flocculation-disinfection using a waterpurifying product)
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. These efforts are spearheaded by the International Network to Promote Household Water Treatment and Safe Storage, a consortium of interested UN agencies, bilateral development agencies, international nongovernmental organizations, research institutions, international professional associations, and private sector and industry associations (WHO, 2008d)
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As the growth of distributed energy systems reduces energy costs to levels supportable by microfinance, more people will be able to invest in small-scale infrastructure appropriate to the developing world, he added. Microfinancing can also support businesses based on safe water or sanitation, such as the use of fecal matter to generate electricity.
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Understanding how to use different grades of water safely will help to address potentially conflicting needs for water quality and quantity. Improving Sanitation.
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. As Kolsky, of the World Bank, wryly observed, it is a frequently overlooked truth that drinking clean water does not entirely protect us from the "fecal peril." Fluids are but one route of invasion for fecal pathogens; as shown in Figure WO-15, sanitation and hygiene are necessary to close the others.
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As a result, the bank's relatively small contribution of about $500 million was leveraged into interventions that are likely to enable the country to meet the water and sanitation MDG, Alavian reported. Since people invest in water and sanitation primarily for reasons unrelated to health, and therefore health improvement is not a priority for the design, construction, and operation of water supply and sanitation infrastructure, the World Bank must determine how to make investments in such projects as beneficial as possible from a public health standpoint, Kolsky said.
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Global phenomena, local effects While the global water crisis may be viewed as a byproduct of interdependent global phenomena that includes population growth, industrialization, climate change, and urbanization, its impact on public health is locally variable, necessitating local solutions. Ecological factors contributing to infectious disease emergence are particularly influential in the case of water-related diseases.
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Human behavior From the implementation of individual interventions, to the resolution of border conflicts over water access, to international cooperation necessary to avert a global water crisis, success depends upon human actions and interactions motivated by diverse factors, of which a scientifically sound assessment of risk and benefit is but one. Interventions to Address Water-Related Diseases Interventions to improve health by increasing water quality, sanitation, and hygiene can be implemented at many points throughout the water distribution system, from source to household to consumer.
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with permission from the World Health Organization. In areas where the water supply is adequate, the adoption of simple and inexpensive methods to improve the microbiological quality of existing water supplies can significantly mitigate the disease burden due to diarrheal diseases.
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The effectiveness of these and other interventions, such as sanitation and water quality management, to reduce the burden of water-related diseases will be strongly influenced by local conditions, which must be taken into account in order to make cost-effective choices to address water-related health risks in diverse contexts (Clasen and Cairncross, 2004)
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• What role does handwashing play in reducing the prevalence and inci dence of respiratory diseases in the developing and developed world? • What are the infectious disease risks associated with the unregulated components of the water distribution "system," including but not limited to private systems (private community and individual wells)
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2007. Treating water with chlorine at point-of-use to improve water quality and reduce child diarrhea in developing countries: a systematic review and meta analysis.
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2007. Published case studies of waterborne disease outbreaks -- e vidence of a recurrent threat.
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1993b. Soil and water quality: an agenda for agriculture.
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2008. The impact of a school-based safe water and hygiene programme on knowledge and practices of students and their parents: Nyanza Province, western Kenya, 2006.
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2008d. International network to promote household water treatment and safe storage, http:// www.who.int/household_water/network/en/ (accessed March 27, 2008)
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