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Institute of Medicine (US) Forum on Microbial Threats. Global Issues in Water, Sanitation, and Health: Workshop Summary. Washington (DC): National Academies Press (US); 2009.

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Global Issues in Water, Sanitation, and Health: Workshop Summary.

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1Global Problems, Local Solutions


In order to appreciate the complexity of the global water crisis, it must be viewed from multiple perspectives, and its effects considered on scales ranging from the individual to the planet. This chapter offers several opportunities for reflecting on the necessity of safe water and sanitation services, the consequences of their increasing scarcity, and the potential for addressing these consequences within communities, at the national level, and through international cooperation.

We begin, not with an essay or review, but with the 18-minute film Running Dry, on the DVD included with this volume and which opened the workshop. The film’s writer, producer, and director, James Thebaut, said that his work was inspired by the book Tapped Out (Simon, 1998), by the late Senator Paul Simon. The film examines 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 arguments for international cooperation on water issues and highlights some promising grassroots programs to improve access to safe water.

Grassroots efforts to improve water access, sanitation, and health are also featured in the chapter’s second contribution, by Donald R. Hopkins of the Carter Center. In the course of recounting the histories of two programs supported by the Center and undertaken in Africa—the first to control trachoma in Ethiopia; the second to eliminate dracunculiasis (Guinea worm disease) in Ghana—Hopkins demonstrates the key role of behavioral change as a determinant of success for public health interventions.

A detailed understanding of waterborne pathogen transmission pathways can inform the development and implementation of effective interventions to prevent and control diseases. Such analyses, characterized in the chapter’s third contribution by David Bradley of the London School of Hygiene and Tropical Medicine, highlight the importance of the household as a target for clean water interventions and the critical role of water access, as distinct from water quality, in preventing water-related diseases. In 1972, Bradley and coworkers published the first functional classification of water-related diseases according to their routes of transmission (White et al., 1972). This now widely used scheme structures and clarifies information critical to interdisciplinary efforts to address the health effects of water and sanitation (see also Workshop Overview). Bradley revisits and critically reviews his original taxonomy of water-related disease, and suggests several modifications to incorporate recent research findings, such as the involvement of the respiratory tract in certain water-related diseases (e.g., Legionnaire’s disease; respiratory infections controlled by hand washing).

Taking the same approach to the study of sanitation and disease, Bradley and coworkers identified six sanitation-related transmission categories to inform the choice of preventive measures for a given disease (see Table WO-3 in the Workshop Overview). Bradley presents and explains this classification scheme and describes its possible integration with the functional taxonomy of water-related disease. To further advance the understanding of waterborne disease transmission processes provided by functional taxonomies, he also explores the systematization of hygiene behavior and the spatial structure of water and sanitation services. Finally, in order to assess the relevance of these concepts, Bradley applies them to a real-world system in southwest Uganda.

In much of the developing world, “water is often collected from sources of dubious quality, hauled over a distance, and stored in the home before it is consumed,” observe workshop speaker Robert Tauxe, of the Centers for Disease Control and Prevention (CDC), and coworkers, who contributed this chapter’s final essay. Water gathered in this way is vulnerable to contamination between its source and its point of use, and thus requires the most local of interventions in order to ensure its safety: household water treatment and storage interventions (also known as “point-of-use” strategies). Tauxe and colleagues discuss the concept and practice of point-of-use water treatment and review findings of recent implementation trials of this strategy in diverse settings that demonstrate its impact on public health; some of these trials featured the effective integration of point-of-use interventions with hand washing and other public health strategies. The authors also explore the critical connection between water- and foodborne disease through a series of case studies, all of which illustrate the global effects of local water quality.


Donald R. Hopkins, M.D., M.P.H. 1

The Carter Center

While others are reaching the moon, we are trying to reach the villages.

Julius Nyerere

The Carter Center’s motto is “Waging Peace, Fighting Disease, Building Hope.” Our divisional motto in the Health Programs of The Carter Center is “Fighting Disease and Building Hope at the Grassroots.” It is in the spirit of that motto that I shall review aspects of two programs we are assisting: illustrating the interaction of water and health in the fight against dracunculiasis (Guinea worm disease) in Ghana, and the interaction of sanitation and health in the fight to control trachoma in Ethiopia. The importance of behavioral change as well as biologic control measures is also greatly evident in both programs.

Trachoma Control in Ethiopia

Trachoma is a chronic bacterial infection of the eye that is caused by Chlamydia trachomatis (Figure 1-1). With an estimated 8 million blinded victims, comprising 16 percent of the global burden of blindness, trachoma is the leading cause of preventable blindness in the world, and an estimated three-quarters of its blind victims are women. About 500 million persons, or about 10 percent of the world’s population, are at risk of the disease, and some 63 million are estimated to have active trachoma in 56 countries. In its early stages, the disease is characterized by inflamed inner surfaces of the eyelids, which yield pus and related secretions around the eye, to which certain species of flies (Musca sorbens) are attracted. The bacteria are spread from one person to another by the flies, and by contaminated fingers, cloths, towels, sheets, or other fomites. After repeated infections, the inflamed inner surfaces of the eyelids become scarred and contract, turning the eyelashes inward, causing them to scrape the eyeball, which is extremely painful. The subsequent scarring of the cornea of the eye itself causes blindness. Women are affected more than men because young children are the reservoirs of infection in the remote, poor, dusty, and unhygienic villages where this infection flourishes, and women suffer repeated reinfections because of their close association with their children (Mabey et al., 2003).

FIGURE 1-1. Patients with early (left) and late (right) trachomatous infections.


Patients with early (left) and late (right) trachomatous infections. SOURCE: Reprinted from WHO (2009) with permission from the World Health Organization.

The World Health Organization (WHO) has developed a four-pronged approach, called the “SAFE strategy,” which combines curative and preventive control measures for achieving sustained reductions in prevalence of the disease (Emerson et al., 2006). The S stands for surgery to correct inward-turning eyelashes and thus prevent progression to blindness if the surgery is conducted early enough. The A is for mass distribution of antibiotics to cure active phases of the infection, although people do not develop immunity and are still subject to reinfection. The F stands for face (and hand) washing, which decreases attraction of the disease-bearing flies by removing secretions and dirt. The E denotes environmental improvement, especially measures to prevent humans from defecating on the ground, where such deposits are preferred breeding sites for M. sorbens (Emerson et al., 2001).

Worldwide, Ethiopia2 is most affected by trachoma, and the Amhara Region (population ~19 million) of Ethiopia contains 31 percent of the active trachoma in the country (Emerson et al., 2006). In partnership with national and regional health authorities and local Lions Club members, and with support of the Lions Club International Foundation, Pfizer Inc. (which donates Zithromax® antibiotic via the International Trachoma Initiative), and other donors, in October 2000, The Carter Center began assisting efforts to eliminate blinding trachoma from the Amhara Region of Ethiopia by 2012. This elimination campaign emphasizes all four components of the SAFE strategy, but the E component is of particular relevance here.

Since latrines are the main intervention to prevent people from defecating on the open ground and thus denying suitable breeding places for M. sorbens, the program in Amhara Region began encouraging villagers to construct and use latrines as part of the effort to prevent trachoma. With the support of local health and administrative leaders and Ethiopian Lions Club members, villagers in an initial area comprising parts of four districts built 1,333 simple latrines in 2002 at negligible cost beyond the labor for digging the individual pits, by taking advantage of favorable local geology and a plentiful supply of available wood, mud, and thatch (Figure 1-2). After other villagers in the area built 2,151 latrines in 2003, the program set an ambitious goal to build 10,000 latrines in 2004. What happened next astonished all who were concerned.

FIGURE 1-2. Example of a latrine in Amhara Region of Ethiopia.


Example of a latrine in Amhara Region of Ethiopia. SOURCE: Courtesy of The Carter Center/L. Rotondo.

As villagers were mobilized to build latrines to prevent trachoma, women and girls began to take special interest for their own reasons, since local tradition allowed men to defecate in the open during the day, but forced women to wait until dark so no one could see them. One woman commented, “I am a prisoner of the daylight.” Women’s groups began pushing their husbands and other male relatives to dig latrines, which soon became status symbols and a focus for competition among families, villages, and officials. Villagers built not just 10,000, but more than 89,000 latrines in 2004 (O’Loughlin et al., 2006), and over 144,000 more latrines in 2005. Another woman was quoted as declaring, “Now we are equal to the men!” and another vowed, “We’ll never go back [to defecating in the field]!” After temporarily diminished output due to insecurity related to national elections, and program emphasis on distributing mosquito nets, over a quarter million latrines were constructed between January and August 2008 (Figure 1-3). This surprising feministled explosion in latrine building will not only help prevent trachoma but will undoubtedly reduce the spread of several intestinal parasites and diarrheal diseases as well. This experience also shows how quickly people will change their behavior when they perceive a rational reason for doing so.

FIGURE 1-3. Carter Center-supported household latrine construction in Ethiopia. *2008 data are provisional, January-August.


Carter Center-supported household latrine construction in Ethiopia. *2008 data are provisional, January-August. SOURCE: Courtesy of The Carter Center.

Dracunculiasis Elimination in Ghana

Dracunculiasis (Guinea worm disease) is a parasitic infection caused by the nematode Dracunculus medinensis (Figure 1-4). The infection is manifest by one-meter-long thin white worms that emerge directly and slowly through the skin on any part of the body. The resulting pain incapacitates victims for periods averaging two to three months and severely constrains agricultural productivity and school attendance. People are infected by drinking water that contains tiny water fleas that have ingested immature forms of the parasite that have been spewed into stagnant ponds from emerging adult worms. This infection is only transmitted by contaminated drinking water, and there is a one-year lag between infection and emergence of the adult worm. Dracunculiasis also has no animal reservoir other than humans, no vaccine or cure, and infection confers no immunity to reinfection. It can be prevented, however, by teaching villagers to filter their drinking water through a fine cloth and to not enter sources of drinking water when a worm is emerging; by treating unsafe sources monthly with a mild larvicide, ABATE®, which is safe for humans; and by providing safe sources of drinking water such as from borehole wells (Hopkins and Ruiz-Tiben, 1991).

FIGURE 1-4. Guinea worm emerging.


Guinea worm emerging. SOURCE: Courtesy of The Carter Center/L. Gubb.

In 1986, dracunculiasis infected an estimated 3.5 million persons and some 120 million persons were at risk of the disease in impoverished rural areas of India, Pakistan, Yemen, and 17 affected African countries (Watts, 1987). Ghana3 was the second-most highly endemic country for dracunculiasis, enumerating nearly 180,000 cases during its first nationwide village-by-village search for cases of the disease in 1989–1990. Ghana’s poor, arid, and long-neglected Northern Region, which includes one-third of the land mass of the country and the lowest rates of literacy, school attendance, and access to safe drinking water and medical care, was found to contain 56 percent of all cases.

With early external support from The Carter Center, the U.S. Centers for Disease Control and Prevention (CDC), the U.S. Agency for International Development (USAID), the Japan International Cooperation Agency (JICA), the United Nations Children’s Fund (UNICEF), the Danish Bilharziasis Laboratory, and enthusiastic support from then head of state Flight Lieutenant (retired) Jerry John Rawlings, Ghana’s Guinea Worm Eradication Program made impressive progress initially, reducing cases by 95 percent between 1989 and 1994, from 179,670 to 8,432. As a result of JICA’s targeted provision of 159 borehole wells in the Northern Region’s agriculturally fertile Nanumba District in 1988–1989, for example, cases of dracunculiasis in the district plummeted by 77 percent in one year, from ~14,000 to ~3,000 between 1989 and 1990, with substantial associated increases in local yam production.

A disastrous and ill-timed outbreak of ethnic fighting in the most highly endemic areas of the Northern Region in 1994–1995 inaugurated a 12-year-long period of programmatic stagnation that has been overcome only in the past two years (Figure 1-5). Some of the long-standing historical enmities at play in the volatile region include memories of slave raiding during the Atlantic Slave Trade, and earlier twentieth century battles that preceded the “Guinea Fowl War” of 1994–1995 (Dawson, 2000; Skalník, 1987). These and other factors such as strongly held traditional beliefs about the disease were manifest over the past five years by the predominance of cases in one or another of the different ethnic groups. Addressing the latter challenges required targeting training, mobilization, and health education efforts to members of specific ethnic groups and their leaders, once their relatively low participation was belatedly recognized.

FIGURE 1-5. Ghana Guinea Worm Eradication Program. Number of cases of dracunculiasis reported by year, 1989–2008 (1989^ national case search; 2008* number is provisional).


Ghana Guinea Worm Eradication Program. Number of cases of dracunculiasis reported by year, 1989–2008 (1989^ national case search; 2008* number is provisional). SOURCE: Courtesy of The Carter (more...)

Without a vaccine or curative drug, in Ghana and elsewhere the global Guinea Worm Eradication Program has had to rely on persuading large numbers of conservative villagers to change their behavior. The obvious horror and easy diagnosis of clinical dracunculiasis are advantages in that regard, but the one-year-long incubation period between infection by drinking contaminated water and appearance of the disease, and the strong traditional beliefs associated with the disease (Bierlich, 1995), are distinct disadvantages. Filtering water from the local source of drinking water, backwashing the filtered material into a clear jar or glass, and letting villagers see the numerous water fleas (and other microscopic organisms) swimming around in the water they were drinking is a very effective tool for convincing villagers to filter their water before drinking it. It also helps them understand how and why the infection comes from their drinking water.

In Ghana and other dracunculiasis endemic countries, unfavorable geologic (Hunter, 1997) and sociologic factors, expense, political pressures, indifference, corruption, and managerial incompetence have often impeded attempts to bring the water supply sector to bear in endemic areas. The dramatic impact realized by the JICA project cited above has been much rarer than it ought to be in the Guinea worm eradication campaign. But advocacy by health workers in this eradication campaign for consideration to be given to distribution of disease in establishing priorities for providing and rehabilitating sources of drinking water has at least helped affirm that important principle for future decision makers.

Meanwhile, the global Dracunculiasis Eradication Program has reduced cases of the disease from the estimated 3.5 million cases in 20 countries in 1986 to a projected total of less than 5,000 cases in 6 countries in 2008, with the overwhelming majority (98 percent) of remaining cases in Sudan, Ghana, and Mali, and falling fast (Hopkins et al., 2008a,b; Figure 1-6). The goal is to try to stop all transmission of dracunculiasis by the end of 2009.

FIGURE 1-6. Number of reported cases of dracunculiasis by year, 1989–2007.


Number of reported cases of dracunculiasis by year, 1989–2007. SOURCE: Courtesy of The Carter Center.


I am grateful to Dr. Ernesto Ruiz-Tiben, director of The Carter Center’s Guinea Worm Eradication Program, and his staff; to Dr. Paul Emerson, director of The Carter Center’s Trachoma Control Program, and his staff; to the many village volunteers, health workers, local Lions Club members in Ethiopia; and to The Carter Center’s numerous donors for their support and participation in the work reported here. I also thank my executive assistant, Ms. Shandal Sullivan, for assisting me in preparing this manuscript.


David J. Bradley 4

London School of Hygiene and Tropical Medicine


This paper seeks to do three things, all related to functional classification, or taxonomy, of water-related diseases. The first is to revisit the taxonomies of diseases related to water and to sanitation that I put forward more than 30 years ago, review them critically, and suggest modifications. The second is to venture into some unsystematized areas that need attention in the epidemiology of water-related diseases in space and time. Third, I shall use a small area of southwest Uganda to show the complexities, related to change, opportunities, and research questions, being raised by water-related disease. Overall, this paper will tend to take a “water’s eye view” of disease transmission.

In Defense of Functional Taxonomies

A classification is a qualitative model using distinctions that matter. Useful classifications of living beings or other phenomena enable simplification of the natural world or of human experience and are a form of conceptual model which, by making generalizations possible, can make communication across different disciplines easier. In public health, where analysis is often performed by physicians or by epidemiologists, while successful interventions often depend on engineers or on policy makers and planners, classifications can be very helpful, especially functional classifications that point toward common interventions and are formulated in the technical language of those who are expected to implement control measures.

In the case of water-related diseases, progress in explaining the issues to engineers and others who manage water had been impeded in two ways: a limited perception and an inappropriate classification. Because water-related pathogens fall into several different biological groupings (i.e., criteria, viruses, protozoa, and helminths), they have been conventionally discussed in those terms, although the modes of water-related transmission cut across these biological categories. Hence, a functional classification of modes of transmission is more useful to those in charge of interventions to control disease. It also avoids what they might view as biological jargon since they would lack the useful connotations that would be apparent to a microbiologist. The limited perceptions of water-related disease in the world as a whole resulted from using the simplified list of infections seen in richer temperate countries and addressed in the conventional texts of those countries. Since piped water to all dwellings was taken as a given, the problem focus was upon pathogens in the water itself, contracted by drinking the water. The broad spectrum of water-related diseases was therefore reduced to a subset and the term waterborne diseases was inappropriately used for the whole lot, with the consequent narrow focus on microbiological water quality that has limited the range of interventions as well as implying a single transmission route, which is far from true.

Our introduction of a broader approach—of dividing water-related communicable disease transmission into four functional categories—seemed to meet the need for a way of communicating across disciplines and has become widely accepted (White et al., 1972). It had quite large policy consequences for water supply in particular and has been used chiefly for work in tropical poor countries, where the populations are exposed to the full range of water-related pathogens. However, it has been rarely critically reviewed, and this is done in the next section.

Since our group turned its attention from water to sanitation (here used in the narrow sense of excreta management), it was logical to attempt a functional categorization of sanitation-related infections (Feachem et al., 1983). This proved to be somewhat more complex, and so less elegant, and, because sanitation is less often discussed than water, the classification is less well known and therefore is set out and discussed later in the section on functional classification of sanitation-related diseases.

Both water- and sanitation-related functional classifications of disease transmission were addressed, particularly to public heath engineers, planners, and geographers—chiefly the first of these professions. Can functional classifications have a wider relevance? A major focus of water- and sanitation-related health research in the past two decades has been on human behavior. The spatial element of sanitary activity has also become more tractable with the development of geographical information systems. Moreover, the dynamic nature of many poor communities has become apparent recently—even rural areas may be undergoing rapid environmental and population changes that are highly relevant to water-related disease patterns. The section on new areas for systematic attention gives a tentative exploration of types of functional taxonomy that might prove relevant to these dimensions of the problem. Lest these endeavors appear too abstract, the final section applies these concepts to a very rapidly changing area of Uganda and explores their relevance in the real world.

The Functional Classification of Water-Related Disease Transmission Revisited

The original classification of water-related disease transmission was developed for a study of domestic water use in East Africa. It aimed to be more comprehensive than the previous narrow “waterborne disease” textbook focus and to separate out the epidemiological processes involved. One consequence was that some diseases fell into two categories—but this was not a disadvantage if it showed that two distinct interventions were required to control transmission (White et al., 1972). There were four categories, as set out in Table 1--1, which also links interventions to categories. From a policy viewpoint, the clear separation of the first two categories, the “strictly waterborne” and the water-washed aspects of transmission, had the most significance, in particular because it drew attention to problems of access to enough water for personal and household hygienic purposes as well as water quality. Since there were many opportunities for improving one aspect at modest cost, even when the other might be financially unaffordable, this spurred operational improvement of rural water supplies and gave emphasis to opportunities that had previously been neglected in favor of urban activities. The formulation of a “waterwashed” modality, whereby disease burden might be reduced by making water more available even if its quality were not fully ideal, also pointed to research questions that had been neglected, the answers to which also led on to the issues of hygiene behavior which were of great importance from the 1990s onward.

TABLE 1--1. Revised Classification of Water-Related Disease Transmission.

TABLE 1--1

Revised Classification of Water-Related Disease Transmission.

Because both water access (quantity used) and microbiological quality affected transmission of many diarrheal diseases, those primarily wanting a simple “pigeon-hole” for each infective disease sometimes lumped them together as fecal-oral diseases, which simplified grouping but lost the analytical and interventional distinctions between quantity and quality, which is of particular importance in highly resource-constrained environments and communities. The third and fourth categories—of water-based diseases (helminths with aquatic intermediate hosts) and water-related insect vectors—both drew attention to further hazards of undeveloped or poorly managed surface water sources and also brought together two previously disparate literatures and areas of study: domestic water supply and diseases of water resource development (such as reservoir construction and irrigation projects), to their mutual benefit (Bradley, 1977a,b; Ensink et al., 2002; Moriarty et al., 2004).

Overall, the water classification has been little criticized and rather widely accepted. However, detailed epidemiological and pathophysiological study of pathogens, and in particular the discovery of many previously unknown pathogenic viruses and bacteria in recent years, has made reassessment overdue.

I believe there is a need for a fifth primary category of transmission, and development of the secondary categories is also needed to incorporate recent research.

It is now clear that bacteria of the genus Legionella are spread from infected persons in water but normally produce secondary infections by inhalation and consequent infection of the respiratory tract, and usually not through the intestinal tract (Szewzyk et al., 2000). This makes for important epidemiological differences in terms of patterns of transmission and preventative measures. Legionella has become the most common single cause of water-related infection in the United States and therefore is no longer a rarity. Its transmission is often related to air-conditioning systems and not only domestic water use in the conventional sense, giving an added reason for its separate categorization. For all those reasons a fifth primary category of water-aerosol transmission has been added to Table 1--1.

The respiratory tract is also involved in an addition to the secondary categories. Currently the water-washed diseases, primary category 2, are subdivided into the diarrheal diseases and the body surface infections that are affected by water availability for hygiene purposes: this latter group may be viewed as a single category or, more usefully, as two: skin infections and trachoma, a potentially blinding infection of the conjunctiva of the eye.

Recent work has demonstrated that provision of water for hygiene purposes, coupled with soap and education in their proper use, is in some poor communities associated with a reduction in respiratory tract infections. The number of such studies is limited (Rabie and Curtis, 2006), but there does appear to be a need for a category of water-washed respiratory infection transmission, which has also been added to Table 1--1.

There is a further way in which water affects disease transmission. In semi-arid areas, sources of surface water may be both few and small in size, and in great demand not only by people and their livestock but also by wildlife in the area. The resulting multispecies crowding around waterholes may greatly facilitate both intraspecific and interspecific transmission of communicable diseases. If our interest extends to new pathogens and emerging diseases this is highly relevant, particularly because the majority of human emerging diseases in recent years have been zoonoses. One could, therefore, add a sixth category to Table 1--1—water-crowding diseases; this is placed tentatively with the other more directly water-related transmission.

Functional Classification of Sanitation-Related Diseases

The apparent utility of the functional classification of water-related disease naturally led to exploration of a similar approach to sanitation and disease. This was presented in a short chapter of a rather large volume (Feachem et al., 1983) and seems to have largely escaped critical attention. It is therefore outlined here as a preliminary to exploring how the two classifications may be integrated. There is a substantial overlap between the diseases related to water and those related to sanitation, both because they are different phases of a single transmission cycle in many cases—sanitation deals with the pathway out of the infected host while water may be route of entry into a new host by a pathogen—and also because the public health engineer is heavily involved in both aspects.

Three characteristics of excreted pathogens strongly affect transmission: latency, persistence, and multiplication. Some pathogens are immediately infectious on emerging from the host in the feces but others have a latent period lasting from a few hours to several weeks before they are infectious. The latter are more likely to be transmitted some way away from where the feces were passed. Excreted pathogens vary greatly in their ability to survive outside the human body: eggs of the helminth Enterobius survive only briefly and are readily transmitted from the anus (where they adaptively give rise to itching) to the mouth in young children. By contrast, the eggs of the large roundworm Ascaris are very resistant and persist for up to several years in the ground, so that there is much more time for them to be carried to other places. Often latency and persistence are combined in the same helminth species so that these have a very different epidemiology than do short-lived species without latency. The former are much affected by the long-term fate of excreta and their management, while the latter are more influenced by personal hygiene behavior and the immediate condition of the latrine or toilet. The third bioenvironmental variable is whether the pathogen multiplies in the excreta, or in some component of the biological environment, or not at all outside the human host.

An empirical classification on the basis of these three variables gives rise to five categories (Table 1-2). The first two lack latency, with the second having a longer persistence and sometimes multiplication in the excreta. Categories III-V show latency, marked persistence in the case of category III, while category IV undergoes development in another mammal before becoming infective to people at the mature sexual stage, and category V develops in aquatic intermediate hosts. A sixth category is for infections transmitted by insects that are sanitation-related, such as the Culicine mosquitoes that thrive in heavily organically polluted waters, cockroaches, and some flies.

TABLE 1-2. Excreta-Related Transmission.


Excreta-Related Transmission.

The categories are related to the relative efficacy of various sanitary interventions. Human hygienic behavior (and particularly hand washing with soap) is most effective in the first two categories of disease transmission, the sanitary infrastructure affects categories II–IV the most, and the last two categories are most dependent on rather specific measures unless the general sanitary standard is relatively high.

Thus, the classification gives a sense of the most important means of control for particular diseases: whether personal hygiene behavior, domestic water supply, provision of toilets and how they are maintained, eventual treatment of the excreta, or very specific methods of attack are most cost-effective. These in turn indicate what level of intervention is likely to be most effective, whether at the individual (e.g., hand washing), the household (toilet provision), or the community level (sewage treatment).

The utility of the separate water-related disease and sanitation-related disease classifications is, for public health engineers, particularly in relation to choosing appropriate water and sanitation improvements, respectively, in conditions of limited resources. It is possible, as shown in Figure 1–7, to link the two systems, though this tends to make things look more complicated than is necessary. If this is to be done, the third component of the complex system—the importance of hygiene behavior—needs to be imported, as in the next section.

FIGURE 1-7. Relation of water- and excreta-related transmission categories.


Relation of water- and excreta-related transmission categories. Some waterborne and some water-washed diseases are also related to excreta, in both categories I and II; the water-aerosol diseases (more...)

Three New Areas for Systematic Attention

The two preceding classification systems have facilitated communication between epidemiologists and public health engineers by linking transmission ecology to specific modes of intervention. But there are other aspects that they ignore or address indirectly. Two such areas are hygiene behavior and the spatial structure of water-related disease transmission.


Over the past 40 years, there has been a progression in our focus from water in the 1960s and 1970s, through sanitation in the 1980s, to sanitation behavior in the 1990s (Cairncross and Kochar, 1994). The key stimulus for the focus to extend from structures to behavior was the demonstration that hand washing with soap reduced the transmission of cholera and other sanitation-related diseases (Curtis and Cairncross, 2003). Other behavioral issues became apparent also: whether children’s feces were perceived as a health risk or not, the way that distance to water (typically a standpipe) outside the home did not affect the amount of water carried between the source and household over a considerable range of distances, and the recent observation that handwashing with soap also appears to reduce transmission of upper respiratory infections.

Is there a way to classify this growing body of behavioral information relevant to control of water- and sanitation-related diseases to guide the parent, teacher, or health educator? This needs exploration by social scientists. It may be that a simple six- or eight-cell categorization into four levels (person, household, community, and state) and two types (positive actions that are to be encouraged, and things to avoid doing and which need regulation either formally or by cultural pressure, Table 1-3) may be of value in thinking about behavioral-change agendas. Such an approach would be a classification of behaviors, to which the various diseases can be linked. Anything that served to group healthy behaviors in a usable way would be of public health value. There is a sense in which the water-related transmission categories point to appropriate behavior: boiling or filtering water for waterborne diseases, hand washing with soap for the water-washed transmission, avoiding water bodies with water-based disease transmission, and so on. But could there be a wider and more informative approach?

TABLE 1-3. A Possible Way to Group Behavior Change for Water and Sanitation Interventions.


A Possible Way to Group Behavior Change for Water and Sanitation Interventions.


The other aspect of epidemiology that has developed dramatically over recent years concerns spatial processes. In rural and peri-urban sites, especially under the conditions of rapid environmental change that prevail in many developing countries, the factors related to disease transmission are spatially variable and complex. In the periphery of expanding African cities, where a mixture of urban and agricultural activities persists, the location of on-site wells and pit latrines affects disease risk. The management, distribution, and allocation of space between the individual and the community; the dichotomy between public space and private space emphasized by Cairncross; and the successive circles of spaces discussed by Kolsky, may be guides to a possible classification, and matters of scale need attention. Such a spatial analysis could primarily relate to geographical space and distance, as for the sanitation diseases that are best controlled by personal cleanliness after excreting, or by toilet provision, or by the ultimate processing of the excreta. Alternatively, it may relate to political subdivisions of space—communal or public versus personal and private. There is also the publicly funded versus privatized, leading onto allocation of construction and of maintenance costs appropriately: consideration of this led to the challenge of received wisdom by the suggestion that the role of the community was more suitably in building water supplies than in their maintenance.

The types of spatial processes affecting these diseases are diverse, and it is unclear how best to reach a simple but useful way to perceive matters. It is clear that, for water and sanitation, there are some situations where widely used interventions, often assumed to be universally applicable, are inadequate. For example, nomadic populations require special arrangements. As for many health interventions, “one size does not fit all.” If one has a very small number of people using a water source that is polluted only by themselves, is the risk of disease much reduced compared to larger common sources? What are the extra hazards when surface water sources are shared among livestock and people? What special opportunities for disease control result from the many large environmental changes affecting water resources? It is far from clear whether convenient generalizations or spatial classifications can clarify this complexity and aid the public health worker, though there is certainly a need to plan more often in spatial terms than has been usual. A strongly spatial theory of disease transmission is needed for communication with physical planners, especially at the urban periphery.

Spatial issues are of particular relevance in considering emerging diseases. The opportunities for influenza viruses to evolve rapidly in parts of East Asia where ducks, pigs, and wild birds are brought together at water bodies are well known.

Many of the water-related problems of vectors are particularly linked to what goes on in “untidy” pieces of water. In most irrigation schemes or other water developments, there are areas where the ecotone between water and land is relatively unmanaged (as around the junctions of drains, rather than canals, in irrigation schemes) and there are small areas where quite complex, highly bio-diverse areas, involving a variety of domestic animals, as well as people, come into contact. Similarly, small irrigation dams are found in large numbers throughout the tropics and are usually in uncontrolled, disorderly contact with people and livestock. The majority of emerging diseases in recent years have been zoonoses. Other examples are given in the last section.

Finally, one can perhaps usefully classify “agendas” (McGranahan et al., 2001) for change in water distribution and abundance, since in our crowded world, different objectives for change are both coming into conflict and overlapping. The earlier perception of perhaps two agendas (economic development and public health) that could sometimes conflict and at other times be synergetic is now too simple. A basic table of some of these agendas may serve to remind those about to intervene in the name of one of these aims to also consider the impact of their proposed action upon the other agendas. Tables 1-3 and 1-4 show how one might categorize behaviors, although they are not proposed to be of definitive value as they currently stand.

TABLE 1-4. List of Some “Agendas” to Be Considered When Changing Aspects of Water or Sanitation.


List of Some “Agendas” to Be Considered When Changing Aspects of Water or Sanitation.

Water, Health, and Disease in a Changing African Community

The earlier sections of this paper have sought, with variable levels of confidence, simple generalizations to help understand and control water-related disease. This final section is an account of changing patterns of water in an area of Uganda and is used to illustrate the rich complexity and rapidity of change, and the implications for health. A larger scale picture of change is given by the two East Africa-wide surveys with comparable methodology and the same sites but 30 years apart (Thompson et al., 2001; White et al., 1972).

As one travels from Kampala, the capital of Uganda, toward the southwest, the landscape gradually changes from matoke (plantain, cooking banana) plantations to more open and hilly country at a greater altitude with scrub and thornbush in the lower areas and rolling grasslands above. Rainfall is unreliable, and for many decades the land has primarily been used for grazing by the beautiful long-horned cattle of the Hima nomadic pastoralists. Under great pressure from the President of Uganda (a Hima himself), they have become sedentarized, leading to great and complex changes in environment, livelihoods, and economy. The large herds of cattle, kept and viewed as capital assets by the traditional Hima, were to be reduced, leading to livestock production primarily for sale as beef, and with hybridization with exotic breeds to increase milk yield in those kept for dairy herds.

Settlement took place in two stages. The first was the creation of huge ranches and later their subdivision under popular political pressure. The second phase was implemented with disregard for water access so that the traditional routes to water now lie across privatized land and the sources themselves are on private land. This precipitated both the universal creation of farm ponds by settlers and the excavation of communal small “dams” to provide dry-season water. Increasing human populations tended to pump boreholes dry in the arid seasons, cattle spraying against ticks has polluted ponds with insecticide residues, and new matoke plantations have increased transpiration and reduced stream flow. New nucleated settlements have increased point-source pollution; charcoal burning has removed tree cover from large areas. The water source of last resort in drought, Lake Mburo, is in a National Park, and cattle, buffalo, and zebra can be seen drinking its water beside each other. Some communal dams are well looked after and provide “stepping stones” for the fauna to spread out from Lake Mburo and increase biodiversity. Road construction and repair has created borrow pits where malaria vectors breed. Temporary “beehive” huts of grass have been replaced by long-term mud-walled structures with thatched roofs, and those by metal-roofed concrete-block permanent dwellings.

Effects upon water- and sanitation-related diseases have been diverse and complex; some aspects are not well understood and causal chains may be inaccurately inferred or misunderstood.

The Hima traditionally live on a largely milk diet (Jelliffe and Blackman, 1962), so that they are not used to drinking water on a large scale. With the move to a monetary economy and sale of beef and milk, their diet has become more diverse and the degree to which water is used for drinking is changing and has been little studied. Settled populations need their water sources to be more reliable than do households accustomed to a nomadic life moving from one source to another.

Although the policy has been to develop boreholes for domestic water supply, while large parish dams have been made for watering livestock, this distinction is often not followed through. Children minding livestock also bring domestic water back for the household, often from the cattle ponds. The epidemiology of shared polluted water supplies, common to both cattle and people, has been poorly studied. Still less has this situation been recognized in water policy formulation.

Malaria has increased markedly during the past two decades, and this increase was perceived by the Hima as a consequence of sedentarization. It was also hypothesized that the mechanism might be reduced deviation to cattle for blood meals of the putative vector, Anopheles arabiensis, as herd sizes decreased and livestock were housed separately from their owners. However, it was found that malaria had increased across the whole population, including those still nomadic; indeed the burden was heaviest among the recently settled. Currently, the more likely hypothesis is that land allocation is the causal factor. Disruption of routes to water had led to a proliferation of local farm ponds that bred the efficient anthropophilic vector Anopheles gambiae near households. New large parish dams have added to the malaria. Anophelines breed to a limited degree in the dam itself as predators abound in the perennial water, but the water is pumped to cattle troughs surrounded by an inadequate concrete apron, beyond which the spilled water forms puddles that are ideal breeding sites for Anopheles gambiae.

Sanitation for nomadic households in a semi-arid environment is very different from settled farming circumstances, where the same area may be repeatedly exposed to excreta. Moreover, the matoke plantations, where latrines may be dug, provide the shade and moisture suitable for hookworm development and infection of the people.

The combination of National Park and water source of last resort for cattle that comprises Lake Mburo provides an obvious site for the exchange of ticks and other ectoparasites between livestock and wildlife, and it is likely that other pathogens may occasionally be transferred between domestic and wild animals or birds there. Indeed, because water is a need for most mammals, limited surface water sources may lead to multiple species crowding for access and may facilitate transmission of diseases that are not waterborne in any usual sense of the word.

All these specific situations occur in addition to the water-related diseases that are associated with increasing population density, incipient urbanization, poverty, and other widespread processes in tropical rural areas. The detailed long-term interdisciplinary study of populations and environments under complex rapid change is likely to provide much helpful input to water and sanitation policies and their implementation.


Many of the ideas summarized in these classifications owe much to my collaborators over the years, particularly Sandy Cairncross, John Thompson, Richard Feachem, and above all, Gilbert and Anne White. Central to the work in southwestern Uganda have been Joseph Okello-Onen and Charles Muchunguzi. To all of them, I am most grateful.


Robert V. Tauxe, M.D., M.P.H. 6

Centers for Disease Control and Prevention

Robert E. Quick, M.D., M.P.H. 7

Centers for Disease Control and Prevention

Eric D. Mintz, M.D., M.P.H. 8

Centers for Disease Control and Prevention


The developing world is hazardous for young children. An estimated 10 million young children died there in 2006 (Anon, 2008). Of these deaths, the World Health Organization (WHO) estimates that 16.5 percent, or at least 1.65 million, were due to diarrheal diseases, many of which were caused by contaminated water (WHO, 2008). In addition to deaths related to diarrheal illnesses, deaths caused by nondiarrheal infections like typhoid fever are also related to contaminated water (Crump et al., 2004).

These high mortality rates resemble those of the United States in the late nineteenth century, before the “sanitary revolution” improved urban water and sewer systems. City-by-city investments in those systems dramatically lowered illness and death rates (Cutler and Miller, 2005). For example, in Pittsburgh, Pennsylvania, the overall death rate from typhoid fever dropped from 130 per 100,000 in 1907, just before the water treatment plant opened, to just 24 in 1909, when 75 percent of the population was supplied with treated water (Rosenau, 1928). Municipal waterworks became objects of civic pride, celebrated architecturally as a Greek temple in Philadelphia, and as a Georgian palace in Cambridge, Massachusetts. Now municipalities are challenged to maintain and upgrade those systems as they enter their second century of service.

Similar improvements have been seen recently in parts of Latin American and other emerging economies. These also require substantial financial investment. In 1991, the Pan American Health Organization (PAHO) estimated that $200 billion would be required to complete and modernize the entire water and sanitary infrastructure of Latin America (de Macedo, 1991). Some of this investment has now occurred, resulting in decreases in disease that in some countries are as dramatic as that observed a century ago in the United States and Europe. In 1991, following the arrival of epidemic cholera, a long-planned sewage treatment system was built in Santiago, Chile, that interrupted the use of raw sewage to irrigate food crops (Alcayaga et al., 1993). Within a year, the incidence of typhoid fever in that city decreased by 85 percent, hepatitis A by 58 percent, and no further cases of cholera were reported. In Mexico, the infant death rate due to diarrheal illness dropped from 11.6 per 1,000 live births in 1980 to 0.71 in 2005, a decrease of 93 percent (Sepulveda et al., 2006). The fastest drop occurred from 1990 to 1993, when an interdepartmental Clean Water Program increased the proportion of the population with access to potable water from 58 to 95 percent. While the mortality rates in Latin American and Caribbean children still vary substantially from country to country, the general mortality of children less than 5 years old per 1,000 live births dropped from 55 in 1990 to 26 in 2006 (Anon, 2008), and in 2006, only 5 percent of those deaths were due to acute diarrheal illness (PAHO, 2008).

Although progress has been made, this effort remains incomplete. In the last decade, epidemic cholera has disappeared from Latin America, though it remains rampant in sub-Saharan Africa and South Asia (Gaffga et al., 2007). In South Asia, the estimated death rates for children under age 5 were 83 per 1,000 live births, and in sub-Saharan Africa, 158 per 1,000 live births (Anon, 2008). In many countries in the developing world, particularly those in South Asia and sub-Saharan Africa, large water systems serving the entire population remain a distant hope, because these countries lack the technological and financial tools to support and maintain such systems. Those countries critically need interim solutions that can improve the safety of water now, without waiting for major municipal investments. To succeed, these solutions need to be simple, inexpensive, reliable and sustainable, and implementable at smaller scales, down to the household level.

We review here the general concept of point-of-use water treatment, and some recent implementation trials that have shown what this strategy can achieve in a variety of settings, with demonstrable impact on health outcomes. These interventions grew from our field experience with epidemic and endemic diarrheal diseases around the world. Interventions were evaluated for acceptability and health impact in trials in a variety of settings. If expanded, these and similar interventions can contribute to reaching the Millennium Development Goals by decreasing childhood morbidity and mortality and by increasing access to safe drinking water at the point of use.

These interim solutions also represent a down payment on long-term solutions. They engage the community and demonstrate immediately the value of safe water and hand washing to individuals, schools, clinics, and other community groups, which can ultimately translate into increased demand for adequate municipal services.

These interventions are centered on simple strategies to make water safe at the point of use, to keep it safe until it is consumed, and to promote hand washing with soap. Although building latrines is also a public and private good, good data on health outcomes from intervention trials with latrines are largely lacking, and are not covered in this paper.

Interventions to Make Water Safe at the Point of Use

Traditionally, water and sanitation programs have been the domain of engineers, while preventing the specific diseases that result from unsafe water, poor sanitation, or hygiene has occupied the public health professions, including physicians, epidemiologists, microbiologists, and other public health professionals. In many countries, the two camps have been housed in different agencies or ministries, have had different funding sources, and have been relatively independent of each other. The evolution of decentralized technologies for treatment of drinking water and sewage now allows the public health professions to play a more active role in implementing “engineered” solutions, while engineers are thinking beyond the traditional solutions of piping treated drinking water to consider more broadly how to serve populations without access to clean water or the means to pay for it. In the mid-1990s, we suggested that both groups should consider that point-of-use water treatment by consumers might be a practical and effective means of reducing the risks of waterborne disease (Mintz et al., 1995). Since then a substantial and growing body of research has borne this out (Clasen et al., 2006, 2007a; Wright et al., 2004).

All human communities have some access to water, but the safety of the water they consume is less often assured. At least a billion people fetch their drinking water from surface sources that are inherently unsafe, such as rivers or water holes, and many hundreds of millions more collect their drinking water from “improved sources,” such as wells and municipal standpipes that are more convenient, but which may not protect water from contamination. Both groups then store their drinking water in the home, where further contamination can occur. Indeed, in many parts of the world, municipal systems provide “economic water,” usable for laundry and flushing latrines or toilets and other household purposes, but that requires further treatment in order to make it potable (Moe and Rheingans, 2006).

Many a Slip ‘Twixt Source and Lip (Adapted from the Proverb)

Some “improved” water systems may start with water that is microbiologically safe. However, once the water has flowed past cracked well heads and casings, through poorly maintained pipes laid adjacent to sewer pipes, and has been subject to low and sometimes negative water pressure and other flaws, it is not surprising that the water is often contaminated by the time it reaches the point of collection. As the water is carried home and stored, it can be further compromised by hands and utensils that are dipped into the bucket and by other intrusions. The end result is that the water may be heavily contaminated at the moment that it is consumed, even if it started out as potable. During the cholera epidemic of 1991, in the town of Trujillo, Peru, water tested at the municipal well head was found to have a geometric mean total coliform count of 1 per 100 ml (range 0–1), rising to 6 (range 0–1,100) by the time it reached the standpipes used by neighborhoods with cholera, and to 794 by the time it was stored in the patients’ homes (Swerdlow et al., 1992). When water is hauled home in open containers, this increase can occur even when the source water is free of contamination at the point of collection. This was well illustrated during an outbreak of cholera on the Pacific island of Ebeye in 2000 (Beatty et al., 2004). Many of the 9,000 residents of Ebeye drank water that was fetched from the U.S. military installation on the neighboring island of Kwajalein, where piped, chlorinated, and safe water was available at a dockside tap. Cholera was strongly associated with drinking that piped water after it was hauled back to Ebeye, though water from the Kwajalein tap was free of contamination, and no cases occurred on Kwajalein. A principle co-factor was the use of wide-mouthed containers to transport and store the water. Contamination of water after it is collected may be the rule, rather than the exception. A recent systematic review of data from 57 field studies concluded that microbiological contamination of water between source and point-of-use is widespread, and often significant (Wright et al., 2004). This highlights the need for point-of-use disinfection and safe storage as part of the strategy to improve the safety of the water that is consumed in the developing world, and the need for surveys of water at the point of use rather than at the source to accurately assess the quality of water that is consumed (Mintz et al., 2001; Wright et al., 2004).

Four different approaches to point-of-use water treatment have demonstrated effectiveness at improving water quality and reducing diarrheal diseases: chlorination, combined chlorination-flocculation, filtration, and solar disinfection. These four approaches and programs used to implement them have been well described recently (Lantagne et al., 2007). All have the following in common: (1) a physical or chemical process that removes or inactivates pathogens in the water and (2) a properly designed water vessel that protects the treated water from recontamination during storage. The processes vary in ease of use, in their effects on the taste and appearance of the finished water, and in the cost and “shelf-life” of the materials they use. For example, locally manufactured dilute sodium hypochlorite packaged and promoted for water treatment is easily added to water and will quickly inactivate bacterial pathogens without affecting the appearance of the water, but with a noticeable effect on its taste. A bottle of hypochlorite solution costs on average about 50 cents, and will last a family one month. A silver-impregnated ceramic filter costs approximately $15, will remove pathogens from water, possibly improving its appearance and without affecting its taste, and will last many months if properly maintained. Examples of safe storage containers include: (1) a simple 1-liter polyethylene terephthalate (PET) plastic soda bottle, painted black on one side and used for solar disinfection of water on the roof of a home; (2) a 20-liter jerry can or a modified clay vessel with a narrow mouth, a lid, and a tap that allows users to remove water by pouring while limiting the potential to contaminate the stored water by dipping in cups, utensils, or hands; or (3) the bottom of two interconnected buckets separated by a filter and equipped with a tap for water removal.

Protective Efficacy and Cost-Effectiveness

Intervention trials of point-of-use treatment and safe storage can provide several different types of information. The outcomes can be measures of the microbiological quality of the water at the point of consumption, the presence of disinfectant in the water as an objective indicator of use, disease incidence, and the knowledge and attitudes of the participants. Most point-of-use water treatment practices depend on using specific products, so the uptake, dissemination, and sustainability of the practices can be readily assessed. Where an intervention depends on the marketing of goods, such as a storage vessel or water disinfectant, marketing strategies and business models can be compared.

Trial results show the efficacy of the intervention strategy, as well as a measure of the fraction of diarrheal illness that is related to water. For example, a trial of two methods of point-of-use disinfection in 49 villages in western Kenya showed that diarrheal illness was decreased by between 19 and 26 percent in families that treated their water, and between 17 and 25 percent among children less than 2 years old; all-cause mortality itself was reduced by 42 percent (Crump et al., 2005). This study illustrates both the large health burden of unsafe water on this population and the means to reduce it. An intervention that is based in clinic settings can directly engage the health community in an area that has traditionally been left to the “water ministry.” For example, in Uganda, a trial providing home water treatment and storage to persons with HIV infection consulting an AIDS clinic showed they had a 25 percent reduction in the incidence of diarrheal illnesses, and 33 percent fewer days with diarrhea, compared to others not using the intervention (Lule et al., 2005). As a result of this trial, point-of-use safe water was added to the bundle of routine preventive measures provided to persons with HIV infections though the Global Aids Program clinics in Uganda and four other countries.

It had been thought in the 1980s that improvements in water quality (as measured at the source) yielded less health benefit than did improvements in sanitation, hygiene, and water “quantity.” Perhaps the unnoticed deterioration of water quality from source to the point of use contributed to that perception. Now that paradigm appears to have been incomplete, and it is changing (Clasen and Cairncross, 2004). A growing number of randomized controlled intervention trials conducted in a variety of developing world settings demonstrate that point-of-use water treatment and safe storage strategies are generally effective in reducing the incidence of diarrheal disease and are more effective than interventions focused on improving the quality of water at the source. A Cochrane library meta-analysis of 38 published studies found that point-of-use interventions had an aggregated effectiveness of 44 percent reduction in diarrheal illnesses (range 26 to 58 percent), while interventions focused on the water source reduced diarrheal illness by only 13 percent (range 2 to 26) (Clasen et al., 2006, 2007a). A second meta-analysis of 21 studies, focusing on the impact of home chlorination strategies on children less than 5 years old, found an aggregated reduction of diarrheal disease of 29 percent (range 13 to 42 percent) in that age group, as well as an 80 percent reduction in the frequency of fecal contamination in stored household water samples (Arnold and Colford, 2007).

Proof of health impact and microbiologic effectiveness in research studies provides a strong scientific base, but, to make a difference in the real world, point-of-use treatment methods have to be economically “scalable” and sustainable. An analysis of the cost-effectiveness of water quality interventions found that for sub-Saharan Africa and Southeast Asia, both source and point-of-use interventions were cost-effective, and that a household-based chlorination strategy was the most cost-effective intervention (Clasen et al., 2007b). Larger scale, sustainable implementation models for these point-of-use treatment technologies are the subject of ongoing operational research. Social marketing through the commercial sector by the non-profit nongovernmental organization (NGO), Population Services International has successfully brought locally manufactured hypochlorite-based water treatment products to millions of people across the world (Lantagne et al., 2007). Subsidized or free distribution has been utilized to reach populations affected by natural disasters, and vulnerable populations including persons living with HIV/AIDS, pregnant women, and the poorest poor. Education and distribution through clinics, schools, and other community institutions also boost awareness and adoption.

Integrating Safe Water with Hand Washing Promotion and Other Interventions

Hand washing has been a fundamental public health intervention since Ignaz Semmelweiss (1818–1865) demonstrated that the risk of puerperal fever could be lowered by implementing hand washing with soap among labor and delivery personnel (Semmelweis, 1983). The health impact of hand washing is still readily demonstrable, particularly in children. For example, a large randomized trial that included weekly home visits to promote hand washing was conducted in the slums of Karachi, Pakistan, with approximately 300 households allocated to each of two intervention groups receiving free soap and one control group (Luby et al., 2004). In this trial, in children less than 15 years old in the intervention group, diarrheal disease was reduced by 53 percent, in children less than 12 months old by 39 percent, and in severely malnourished children by 42 percent compared to the children in the control group. The health benefits went beyond diarrheal illness. Compared with controls, children in the intervention group who were less than 5 years old had a 50 percent lower incidence of pneumonia and children less than 15 years old had a 34 percent lower incidence of impetigo (Luby et al., 2005). A meta-analysis of 7 intervention trials and 10 observational studies produced similar results, suggesting that hand washing reduces the risk of diarrhea by 43 percent, severe enteric infections by 49 percent, and shigellosis by 58 percent (Curtis and Cairncross, 2003). Because the implementation approaches used in many of the aforementioned studies were expensive and intensive, it would not be possible to scale up and sustain them by themselves. However, hand washing can be effectively co-promoted with safe water programs and integrated with other public health interventions.

Integrating Safe Water and Hand Washing Promotion in the Clinical Setting

Integration of combined safe water and hand hygiene interventions into health facilities has proven to be feasible and effective. In 2004, the CDC collaborated with the Kenyan Ministry of Health and CARE Kenya to co-promote safe water and hand washing with soap at a district hospital (Parker et al., 2006). Project implementers installed special clay water pots in all outpatient departments and hospital wards and provided sodium hypochlorite solution (with the brand name WaterGuard®) for water treatment and soap for hand washing (Figure 1-8). Hospital nurses were trained in water treatment and hand washing and instructed to provide this teaching to their clients. Exit interviews with 220 clinic clients found that 85 percent of mothers had received education about water treatment, 80 percent on hand washing with soap, and 76 percent on both topics. Two weeks after the exit interviews, home visits were conducted with a random sample of 98 clinic clients and confirmed that 68 percent were using WaterGuard® (by measuring chlorine residuals in stored water), 44 percent of respondents could demonstrate the six steps of hand washing taught by the nurses, and 81 percent could demonstrate at least four hand washing steps. One year later, 71 percent of evaluation households were found to still have detectable chlorine residuals in treated water, 34 percent of respondents could demonstrate all six steps of hand washing, and 98 percent could demonstrate four steps. Five years later, the intervention is still in place at the district hospital (CDC, unpublished data). In the interim, CARE Kenya continued to implement this intervention in hospitals, health centers, and dispensaries. To date, an additional 108 health facilities have installed hand washing and drinking water stations. The curriculum used to train nurses in these programs has been adapted for use in at least five other countries in sub-Saharan Africa and Asia.

FIGURE 1-8. Supervising nurse at a drinking water station at a community clinic in Nyanza Province, Kenya.


Supervising nurse at a drinking water station at a community clinic in Nyanza Province, Kenya. The water is disinfected with a chlorine product, which the clinic also sells, and the clay (more...)

In 2007, a project was launched in antenatal clinics in Malawi to provide free hygiene kits consisting of safe water storage containers, WaterGuard® solution, soap, two sachets of oral rehydration salts, and education to pregnant mothers attending the clinics (Figure 1-9; Sheth et al., 2008). Pregnant mothers also received free refills of WaterGuard® and soap when they returned for follow-up visits. An evaluation of 400 clinic clients showed that, from baseline to follow-up, there was an increase in confirmed use of WaterGuard® from 2 to 61 percent, confirmed purchase and use of WaterGuard® from 2 to 32 percent (suggesting the potential sustainability of water treatment behavior), and the ability to demonstrate correct hand washing procedure from 22 to 68 percent. A concurrent study of friends and relatives of clinic clients showed an increase of WaterGuard® use from 2 to 25 percent and of the ability to demonstrate correct hand washing procedure from 18 to 60 percent, suggesting diffusion of knowledge and practices (Dr. Anandi Sheth, CDC, personal communication, January 2009). A program to offer hygiene kits of WaterGuard® solution and soap as incentives to motivate mothers to bring their infants to clinic is currently underway in western Kenya.

FIGURE 1-9. Water and hygiene kit currently being distributed to expectant women at antenatal clinics in Malawi, including WaterGuard® chlorine disinfectant, Safe Water storage vessel with spigot and lid, and packet with soap and oral rehydration solution.


Water and hygiene kit currently being distributed to expectant women at antenatal clinics in Malawi, including WaterGuard® chlorine disinfectant, Safe Water storage vessel with spigot (more...)

Integrating Safe Water and Hand Washing Promotion into Schools

In 2003, a pilot program at a single private school in Kenya suggested that combined programs of safe water treatment and hand washing with soap were feasible (Migele et al., 2007). In this program, drinking water stations and hand washing stations were provided to the school; teachers were trained about water treatment and hand washing and taught their pupils about these two topics; and safe water clubs were formed so pupils could engage in water and hygiene learning projects. Over the course of the project, trips to the doctor decreased by more than half and the school saved more than $5.00 per pupil. Following this pilot, similar programs were implemented in 60 public primary schools in Kenya (Figures 1-10A and B). An evaluation in 2005–2006 showed that, from baseline to follow-up, pupils’ knowledge of correct water treatment procedure increased from 21 to 65 percent, and of the need to wash hands after using the toilet increased from 73 to 90 percent (O’Reilly et al., 2008). Among parents, increases were observed from baseline to follow-up in reported current use of WaterGuard® (6 percent increasing to 14 percent, p < 0.01), confirmed use of WaterGuard® (5 to 8 percent, p = 0.20), and having soap in the home (74 to 90 percent, p < 0.01). From baseline to follow-up, pupil absentee rates decreased by 35 percent, compared to a 5 percent increase in neighboring control schools.

FIGURE 1-10. Two students in the Safe Water Club at Sino SDA Primary School in Nyanza Province collect and treat the water for the school each morning to (A) fill the handwashing station reservoir and (B) the clay pot with treated water for drinking.


Two students in the Safe Water Club at Sino SDA Primary School in Nyanza Province collect and treat the water for the school each morning to (A) fill the handwashing station reservoir and (more...)

In China, a randomized trial in primary schools where safe water was already available compared schools with a standard program of hand washing education; an expanded program of education, soap, and peer hygiene monitors; and controls schools with no hand washing promotion (Figure 1-11; Bowen et al., 2007). The trial showed that students in the expanded program had significantly fewer episodes and days of absence than did students in control schools; students in schools with the standard program had intermediate rates of both indicators that did not exhibit a statistically significant difference from either of the other two groups. Similar assessments are underway in the Philippines and Pakistan, and an assessment of the long-term impact of hand washing programs on growth and cognitive development is in the planning stages.

FIGURE 1-11. Students at a primary school in Fujian Province, China, washing their hands at the start of the lunch hour.


Students at a primary school in Fujian Province, China, washing their hands at the start of the lunch hour. SOURCE: Figure courtesy of Dr. Anna Bowen, CDC.

Bundling Safe Water and Hand Washing Promotion in the Community Setting

Another strategy that holds promise is to integrate hand washing with soap with other interventions in community programs. The Nyando Integrated Child Health and Education (NICHE) program promotes several proven products for child health: WaterGuard®solution, PuR® flocculent disinfectant (Procter and Gamble, Cincinnati, Ohio), Aquatabs® (Medentech, Ltd., Wexford, Ireland), safe water storage containers, soap, insecticide-treated bed nets, micronutrient Sprinkles (Heinz Co., Toronto, Canada), and de-worming with albendazole (CDC, 2007). These products are part of a basket of goods sold door-to-door to community members at a low price by HIV self-help groups as an income-generating activity. The self-help groups also provide health education and work with schools, local clinics, churches, and local political leaders to expand the promotional messages as widely as possible. Assessment of the success of this program is in progress.

Health Benefits Related to Safer Foods

Safer Weaning Foods

Water is used to prepare many foods in the home, including weaning food. Weaning is a particularly hazardous time for growing children and has been associated with an increase in diarrheal illness and an associated delay in growth (Martorell et al., 1975). Wet foods and gruels used as weaning foods may often be contaminated with fecal coliforms (Henry et al., 1990). In Peru, cereals and purees prepared especially for infants were more contaminated than were the foods prepared for the rest of the family (Black et al., 1989). Household drinking water used in the preparation of weaning foods is one of several important sources of contamination (Motarjemi et al., 1993). It is likely that using safe water and washed hands to prepare these foods would reduce their contamination. It is possible that some of the general reduction in diarrheal illness observed when household water disinfection is practiced is the result of safer foods and safer drinking water. An intervention study remains to be done that evaluates the microbial quality of weaning foods prepared in homes with and without point-of-use water disinfection.

Safer Foods on the Street

Street vendors provide fast, inexpensive, and convenient food and drink in much of the developing world, filling the same social niche that fast food restaurants do in the developed world. Street-vended foods can be safe if they are cooked hot and served fast (Abdussalam and Kaferstein, 1993). However, many are not, and unsafe water often appears to play a supporting role. High levels of contamination with fecal indicator bacteria have been demonstrated in surveys of street-vended food and beverages (Garin et al., 2002), and disease resulting from consuming them has been well documented. In the early 1980s, eating street-vended flavored ices was a risk factor for typhoid fever in children in Santiago, Chile (Black et al., 1985). In 1989, in Manila, Philippines, a cholera epidemic in an area not served by piped water was linked to consuming street-vended foods, particularly to a rice noodle dish, and to mussel soup (Lim-Quizon et al., 1994). In 1991, consuming street-vended foods and beverages was a risk factor for epidemic cholera in Piura, Peru, where the municipal water supply was not chlorinated, and the ice used in beverages may have been particularly risky (Ries et al., 1992). In 1993, a cholera epidemic in Guatemala City, where the municipal water supply was chlorinated, was linked to eating street-vended foods and flavored ices (Koo et al., 1996). From 2001 to 2003, endemic paratyphoid fever was linked to eating foods prepared outside the home, largely as street-vended foods, while typhoid fever was associated with lack of clean water and sanitation inside the home in Jakarta, Indonesia (Vollaard et al., 2004b). The street vendors of Jakarta often had fecally-contaminated hands, ice, and drinking water, and poor hand hygiene (Vollaard et al., 2004a).

Even if street vendors understand the principles of safe food preparation, there is little that they can do without access to safe water for preparing food, washing their hands, and cleaning their utensils and dishes (Mahon et al., 1999). In 1994, we conducted a survey of the knowledge and practices of street vendors in two Guatemalan towns. Most vendors and their customers were aware of the importance of using clean water and hand washing, but none of the vendors did so, perhaps because none had treated water available. In 1996, we provided a cohort of street vendors in Guatemala City with Safe Water® system containers and chorine-based disinfectant (Sobel et al., 1998). Vendors were given soap and encouraged to wash their hands with the clean water, as well as use it to prepare the drinks they sold, made from fruits and cereals. We tested the stored water, beverages, and hands of the 41 intervention vendors and 42 similar but unequipped control vendors for evidence of fecal contamination before and during the six-week intervention period. The intervention was associated with a significant decrease in fecal coliforms in the stored water, and in the beverages that they were selling, though there was little change in the contamination of their hands. The intervention was well accepted. The vendors thought it increased their sales by increasing customer confidence. In a spontaneous innovation, some vendors offered the hand washing platform to their customers, so they could wash their hands before eating. Five months later, the original intervention group of vendors was still using the water disinfection system. Though no assessment of health impact was attempted, the intervention trial showed that making clean water and soap available at the street vendors’ point of use resulted in a less contaminated product. This intervention can be easily adopted as a public health policy and incorporated into ongoing efforts to educate and license street vendors.

Safer Food Processing

Water is used in many stages of food production and processing. For fresh produce that is eaten without further cooking, the quality of the water that is used to spray, wash, and chill the food is linked directly to its safety. This means that the microbiological quality of the water in the developing world is of immediate consequence to consumers in the industrialized world, as well as affecting the health of consumers in the country where the produce is grown. In 2001, 17 percent of fresh and frozen vegetables and 23 percent of the fresh and frozen fruit consumed in the United States was imported, largely from Latin America (Jerardo, 2003). In Europe, a growing fraction of fresh produce is imported from Africa. Outbreaks of foodborne diseases have been associated with important lapses in maintaining the safety of water used to process foods before they were imported. Investigating these outbreaks and tracing them back to their sources is difficult and requires effort, luck, and the cooperation of many parties, so it is likely that the identified outbreaks represent only the tip of the metaphorical iceberg (Tauxe et al., 2008).

Shigellosis and Parsley

In 1998 in Minnesota, two outbreaks occurred of a febrile bloody diarrheal illness caused by the fecal bacterium Shigella sonnei. In one outbreak, an epidemiological investigation linked illness with eating foods made with parsley, while in the other, parsley was strongly suspected though not proven; the parsley source for both events was the same (Naimi et al., 2003). The state health department used molecular methods to fingerprint the Shigella bacteria and showed that the Shigella strains from the two outbreaks were indistinguishable. Public health authorities around the continent were alerted and quickly reported six more outbreaks caused by Shigella sonnei with the same DNA fingerprint as the first two. In each outbreak, parsley was implicated or was strongly suspected. In addition, two other outbreaks of gastroenteritis in Minnesota caused by a second microbe, enterotoxigenic Escherichia coli, also appeared to be linked to parsley. In all, 486 persons were ill with shigellosis and 77 with enterotoxigenic E. coli diarrhea. The combination of two different enteric diseases linked to the same food item across multiple states and countries suggested that contamination by raw sewage had somehow occurred near the point of production. The parsley in these outbreaks was traced to the likely source, a farm in Mexico. Investigators from the Food and Drug Administration (FDA), Mexico, and CDC visited that farm. The farm used local municipal water to rinse and chill the parsley, though the chlorination of the municipal system was inadequate and intermittent. The farm also placed ice made from apparently unchlorinated water on the parsley to ship it chilled to the United States. It is likely that the local water and/or ice contaminated the parsley. Preventing such contamination would require a guaranteed potable water supply for washing and chilling the produce. It seems self-evident that water used to process fresh foods that are eaten without further cooking must be safe to drink.

Jaundice and Green Onions

In 2003, large outbreaks of hepatitis A infections affected customers of restaurants in Tennessee, Georgia, North Carolina, and Pennsylvania (Amon et al., 2005; Wheeler et al., 2005). A total of 1,023 cases were reported. In Pennsylvania, at least 124 of the 601 identified patients were hospitalized, and 3 died. Symptoms were jaundice, abdominal pain, fever, and the prolonged malaise characteristic of this infection in adults. In each location, illness was linked to eating green onions, which were traced back through the supply chain to likely source farms in northern Mexico. In rural Mexico, hepatitis A is a common infection in young children, acquired as a result of poor sanitation and unsafe drinking water, and usually causes relatively mild diarrhea. Investigation of the farms by the FDA, Mexican authorities, and CDC revealed dubious quality of water used in packing sheds and ice machines, poor sanitation and hand washing facilities, and the possibility that young children in diapers were sitting on harvested produce (FDA, 2003). Prevention strategies include ensuring that water used for washing and icing the produce is potable, improving local sanitation and health conditions of farm worker families, and separating young children from harvested food.

Salmonella Newport Infections and Mangoes

One outbreak is a cautionary tale showing how phytosanitary food regulations intended to prevent one problem created another. In 1999, a large outbreak of Salmonella Newport infections sickened at least 78 persons in 13 states and was linked to imported mangoes (Sivapalasingam et al., 2003). The mangoes came from one large orchard in Brazil that also exported mangoes to Europe, where no cases were identified by public health authorities. Investigation of the orchard by Brazilian authorities, FDA, and CDC revealed a difference in how the mangoes were handled that depended on their destination. To prevent the introduction of Mediterranean fruitflies, U.S. regulations mandated that the mangoes be disinfested. However, mangoes destined for Europe were not disinfested, because Mediterranean fruit flies are native to Europe. In the past, the mangoes were fumigated with ethylene dioxide gas, which has toxic effects on workers and the ozone layer, as well as on fruit flies. In the 1990s, the United States began to require dipping mangoes in a hot water bath instead. At the Brazilian orchard, the hot water dip was followed by a cold water dip to cool the mangoes. The sudden transfer of a hot mango into a cold water bath makes the interior of the fruit contract slightly, pulling water inside along with any bacteria that are present (Penteado et al., 2004). Although the quality of the water is critical to the safety of the fruit, treatment specifications did not mandate reliably safe water. The hot water was not chlorinated, and the cold water was only chlorinated once a week, though the tank was open to the tropical environment and was used daily. A point-of-use system that continuously disinfects and protects the water is needed to prevent the contamination of the fruit. One hopes that this is required wherever disinfestation via a hot water dip is mandated.

As these outbreaks demonstrate, the safety of the water used to process foods is related to the health of the consumer. These scenarios offer a window into the safety of food production, whether the food is then consumed locally or exported. Using potable water for processing and chilling is a fundamental good food manufacturing practice. The health of the workers is also likely to be important, so providing clean drinking water, hand washing, and sanitation for workers and their families is not only humanitarian but also a prudent business practice.

Summary and Conclusions

The experiences outlined above show that substantial progress is possible with low-cost, sustainable, and effective interventions. They provide broad health benefits including fewer diarrheal illnesses and respiratory and skin infections, in both children and adults, and they decrease school absenteeism in students and teachers. Hand washing promotion can be easily added to a program that provides safe water at the point of use. Clinics and schools are good venues for introducing these interventions, to educate the public in their use, to target persons at high risk, and to improve institutional hygiene. Social entrepreneurs can distribute and sell safe water treatment products and soap along with other point-of-use health products. Safe water and hand washing is likely to make weaning foods and street-vended foods safer. In addition to local health benefits, safer water for drinking and food processing in the developing world makes fresh produce safer when exported to the developed world.

These interventions are also likely to stimulate social development. Local production and sale of containers and disinfectants can create micro-economies. Successful interventions help people recognize the value of making their drinking water safe and keeping it safe, building a constituency for reliably safer water. Treating household drinking water can be a daily reminder of the desirability of a long-term solution. Rather than slowing demand for treated piped water, the practice of point-of-use disinfection may be an impetus for small community water systems and micro-utilities of increasing social and technical complexity.

However, implementation to date has been limited, and few programs have been scaled up to the national level. Considering all the point-of-use interventions together, only about 1 percent of the billion persons lacking access to safe water have been reached to date (Clasen, 2008). Progress will accelerate if the health-care providers can engage and partner with the water department authorities, bridging the two bureaucracies that are often separate realms. One important step is to introduce water interventions in health clinics, which would likely reduce the risk of disease transmission, model healthy behavior for patients and their families, and bring the medical community into immediate contact with water issues. Progress will also accelerate if household water treatment can be coupled with other major health intervention programs, and promoted as an investment for community health. It can be a low-cost addition to programs for childhood vaccination, malaria control, and for programs to improve the quality of life in persons with AIDS. It can be integrated with maternal and child health programs, preventing illness in the youngest and most vulnerable children. Beyond the clinic, water treatment strategies can be promoted by pharmacists, traditional healers, and birth attendants.

Progress in reaching the benchmarks of the Millennium Development Goals will also be faster if safe drinking water at point of use and handwashing are recognized and promoted as useful strategies. These interventions can reduce a substantial fraction of the childhood morbidity and probably can reduce the mortality that is targeted by Goal #4.9 Goal #710 aims to increase access to safe drinking water, but even if the water comes from “improved” sources there is a demonstrated risk for contamination as it is collected, transported, and stored in the home. Therefore, this goal would have even more health impact if it were amended to focus on increasing access to water that is safe at the moment that it is consumed.

Finally, progress will be faster if decision makers find that interim point-of-use water disinfection is a logical step along the path towards safe piped water in every home.


  1. Simon P. Tapped out: the coming world crisis in water and what we can do about it. New York: Welcome Rain Publishers; 1998.
  2. White GF, Bradley DJ, White AU. Drawers of water: domestic water use in East Africa. Chicago: University of Chicago Press; 1972. [PMC free article: PMC2567632] [PubMed: 11884976]


  1. Bierlich B. Notions and treatment of Guinea worm in northern Ghana. Social Science and Medicine. 1995;41(4):501–509. [PubMed: 7481944]
  2. CIA (Central Intelligence Agency) The World Factbook: Ethiopia. 2009a. [accessed July 14, 2009]. https://www​​/publications​/the-world-factbook/geos/et.html .
  3. CIA (Central Intelligence Agency) The World Factbook: Ghana. 2009b. [accessed July 14, 2009]. https://www​​/publications​/the-world-factbook/geos/gh.html .
  4. Dawson CA. Thesis submitted to the Department of Anthropology. University of Calgary; Alberta Canada: 2000. Becoming Konkomba: recent transformations in a Gur Society of Northern Ghana.
  5. Emerson PM, Bailey RL, Walraven GE, Lindsay SW. Human and other feces as breeding media of the trachoma vectorMusca sorbens. Medical and Veterinary Entomology. 2001;15(3):314–320. [PubMed: 11583450]
  6. Emerson PM, Burton M, Solomon AW, Bailey R, Mabey D. The SAFE strategy for trachoma control: using operational research for policy, planning and implementation. Bulletin of the World Health Organization. 2006;84(8):613–619. [PMC free article: PMC2627433] [PubMed: 16917648]
  7. Hopkins DR, Ruiz-Tiben E. Strategies for dracunculiasis eradication. Bulletin of the World Health Organization. 1991;69(5):533–540. [PMC free article: PMC2393261] [PubMed: 1835673]
  8. Hopkins DR, Ruiz-Tiben E, Downs P, Withers PC Jr, Roy S. Dracunculiasis eradication: neglected no longer. American Journal of Tropical Medicine and Hygiene. 2008a;79(4):474–479. [PubMed: 18840732]
  9. Hopkins DR, Ruiz-Tiben E, Eberhard ML, Roy S. Update: progress toward global eradication of dracunculiasis, January 2007-June 2008. Morbidity and Mortality Weekly Report. 2008b;57(43):1173–1176. [PubMed: 18971919]
  10. Hunter JM. Geographical patterns of Guinea worm infestation in Ghana: an historical contribution. Social Science and Medicine. 1997;44(1):103–122.
  11. Mabey DC, Solomon AW, Foster A. Trachoma. Lancet. 2003;362(9379):223–229. [PubMed: 12885486]
  12. O’Loughlin R, Fentie G, Flannery B, Emerson PM. Follow-up of a low cost latrine promotion programme in one district of Amhara, Ethiopia: characteristics of early adopters and non-adopters. Tropical Medicine and International Health. 2006;11(9):1406–1415. [PubMed: 16930263]
  13. Skalník P. On the inadequacy of the concept of the traditional state-illustrated with ethnographic material on Nanun, Ghana. Journal of Legal Pluralism. 1987;25 and 26:301–325.
  14. Watts SJ. Dracunculiasis in Africa in 1986: its geographical extent, incidence, and at-risk population. American Journal of Tropical Medicine and Hygiene. 1987;37(1):119–125. [PubMed: 2955710]
  15. WHO (World Health Organization) Trachoma. 2009. [accessed April 21, 2009]. http://www​​/causes/priority/en/index2.html .


  1. Bradley DJ. Health aspects of water supplies in tropical countries. In: Feachem RG, McGarry MG, Mara D, editors. Water, wastes and health in hot climates. New York: Wiley; 1977a. pp. 3–17.
  2. Bradley DJ. The health implications of irrigation schemes and man-made lakes in tropical environments. In: Feachem RG, McGarry MG, Mara D, editors. Water, wastes and health in hot climates. New York: Wiley; 1977b. pp. 18–29.
  3. Cairncross S, Kochar V, editors. Studying hygiene behaviour: methods, issues, and experiences. Thousand Oaks, CA: Sage Publications; 1994.
  4. Curtis V, Cairncross S. Effect of washing hands with soap on diarrhoea risk in the community: a systematic review. Lancet Infectious Diseases. 2003;3(5):275–281. [PubMed: 12726975]
  5. Ensink JHJ, Aslam MR, Konradsen F, Jensen PK, van der Hoek W. Working Paper 46. Colombo, Sri Lanka: International Water Management Institute; 2002. Linkages between irrigation and drinking water in Pakistan.
  6. Feachem RG, Bradley DJ, Garelick H, Mara DD. Health aspects of excreta and wastewater management. Chichester, UK: John Wiley; 1983.
  7. Jelliffe DB, Blackman V. Bahima disease. Possible “milk anemia” in late childhood. Journal of Pediatrics. 1962;61:774–779. [PubMed: 13964591]
  8. McGranahan G, Jacobi P, Songsore J, Surjadi C, Kjellen M. The citizens at risk: from urban sanitation to sustainable cities. London: Earthscan; 2001.
  9. Moriarty P, Butterworth J, van Koppen B. Technical Paper Series, no. 41. Delft, the Netherlands: IRC International Water and Sanitation Centre; 2004. Beyond domestic: case studies on poverty and productive uses of water at the household level.
  10. Rabie T, Curtis V. Handwashing and risk of respiratory infections: a quantitative systematic review. Tropical Medicine and International Health. 2006;11(3):258–267. [PubMed: 16553905]
  11. Szewzyk U, Szewzyk R, Manz W, Schleifer K-H. Microbiological safety of drinking-water. Annual Review of Microbiology. 2000;54:81–127. [PubMed: 11018125]
  12. Thompson J, Porras IT, Tumwine JK, Mujwahuzi MR, Katui-Katua M, Johnstone N, Wood L. 30 years of change in domestic water use and environmental health in East Africa. London: International Institute for Environment and Development; 2001. Drawers of water II.
  13. White GF, Bradley DJ, White AU. Drawers of water: domestic water use in East Africa. Chicago: University of Chicago Press; 1972. [PMC free article: PMC2567632] [PubMed: 11884976]


  1. Abdussalam M, Kaferstein FK. Safety of street foods. World Health Forum. 1993;14(2):191–194. [PubMed: 8185771]
  2. Alcayaga S, Alcayaga J, Gassibe P. Revista Chileana Infectiologia. Vol. 1. 1993. Cambios del perfil de morbilidad en algunas patologias de transmisión enterica con posterioridad a un brote de colera. Servicio de Salud Metropolitano Sur. Chile; pp. 5–10.
  3. Amon JJ, Devasia R, Xia G, Nainan OV, Hall S, Lawson B, Wolthuis JS, Macdonald PD, Shepard CW, Williams IT, Armstrong GL, Gabel JA, Erwin P, Sheeler L, Kuhnert W, Patel P, Vaughan G, Weltman A, Craig AS, Bell BP, Fiore A. Molecular epidemiology of foodborne hepatitis A outbreaks in the United States, 2003. Journal of Infectious Diseases. 2005;192(8):1323–1330. [PubMed: 16170748]
  4. Anon.Goal 4: Reduce child mortality. 2008. [accessed December 14, 2008]. http://go​ .
  5. Arnold BF, Colford JM Jr. 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. American Journal of Tropical Medicine and Hygiene. 2007;76(2):354–364. [PubMed: 17297049]
  6. Beatty ME, Jack T, Sivapalasingam S, Yao SS, Paul I, Bibb B, Greene KD, Kubota K, Mintz ED, Brooks JT. An outbreak of Vibrio cholerae O1 infections on Ebeye Island, Republic of the Marshall Islands, associated with use of an adequately chlorinated water source. Clinical Infectious Diseases. 2004;38(1):1–9. [PubMed: 14679441]
  7. Black RE, Cisneros L, Levine MM, Banfi A, Lobos H, Rodriguez H. Case-control study to identify risk factors for paediatric endemic typhoid fever in Santiago, Chile. Bulletin of the World Health Organization. 1985;63(5):899–904. [PMC free article: PMC2536445] [PubMed: 3879201]
  8. Black RE, Lopez de Romana G, Brown KH, Bravo N, Bazalar OG, Kanashiro HC. Incidence and etiology of infantile diarrhea and major routes of transmission in Huascar, Peru. American Journal of Epidemiology. 1989;129(4):785–799. [PubMed: 2646919]
  9. Bowen A, Ma H, Ou J, Billhimer W, Long T, Mintz E, Hoekstra RM, Luby S. A cluster-randomized controlled trial evaluating the effect of a handwashing-promotion program in Chinese primary schools. American Journal of Tropical Medicine and Hygiene. 2007;76(6):1166–1173. [PubMed: 17556631]
  10. CDC (Centers for Disease Control and Prevention) Baseline data from the Nyando Integrated Child Health and Education Project–Kenya, 2007. Morbidity and Mortality Weekly Report. 2007;56(42):1109–1113. [PubMed: 17962803]
  11. Clasen TF. Scaling up household water treatment: looking back, seeing forward. Geneva: World Health Organization; 2008.
  12. Clasen TF, Cairncross S. Household water management: refining the dominant paradigm. Tropical Medicine and International Health. 2004;9(2):187–191. [PubMed: 15040554]
  13. Clasen T, Roberts I, Rabie T, Schmidt W, Cairncross S. Interventions to improve water quality for preventing diarrhoea. Cochrane Database of Systematic Reviews. 2006;3:CD004794. [PubMed: 16856059]
  14. Clasen T, Schmidt W-P, Rabie T, Roberts I, Cairncross S. Interventions to improve water quality for preventing diarrhoea: systematic review and meta-analysis. British Medical Journal. 2007a;334(7597):782. [PMC free article: PMC1851994] [PubMed: 17353208]
  15. Clasen T, Haller L, Walker D, Bartram J, Cairncross S. Cost-effectiveness of water quality interventions for preventing diarrhoeal disease in developing countries. Journal of Water and Health. 2007b;5(4):599–608. [PubMed: 17878570]
  16. Crump JA, Luby SP, Mintz ED. The global burden of typhoid fever. Bulletin of the World Health Organization. 2004;82(5):346–353. [PMC free article: PMC2622843] [PubMed: 15298225]
  17. Crump JA, Otieno PO, Slutsker L, Keswick BH, Rosen DH, Hoekstra RM, Vulule JM, Luby SP. Household based treatment of drinking water with flocculant-disinfectant for preventing diarrhoea in areas with turbid source water in rural western Kenya: cluster randomised controlled trial. British Medical Journal. 2005;331(7515):478. [PMC free article: PMC1199021] [PubMed: 16046440]
  18. Curtis V, Cairncross S. Effect of washing hands with soap on diarrhoea risk in the community: a systematic review. Lancet Infectious Diseases. 2003;3(5):275–281. [PubMed: 12726975]
  19. Cutler D, Miller G. The role of public health improvements in health advances: the twentieth-century United States. Demography. 2005;42(1):1–22. [PubMed: 15782893]
  20. de Macedo CG.Presentation of the PAHO regional plan. Proceedings of the conference: confronting cholera, the development of a hemispheric response to the epidemic; Miami, Florida: North-South Center, University of Miami; 1991. pp. 39–44.
  21. FDA (Food and Drug Administration) FDA update on recent hepatitis A outbreaks associated with green onions from Mexico. 2003. [accessed February 4, 2007]. www​​/NEWS/2003/NEW00993.html .
  22. Gaffga NH, Tauxe RV, Mintz ED. Cholera: a new homeland in Africa? American Journal of Tropical Medicine and Hygiene. 2007;77(4):705–713. [PubMed: 17978075]
  23. Garin B, Aidara A, Spiegel A, Arrive P, Bastaraud A, Cartel JL, Aissa RB, Duval P, Gay M, Gherardi C, Gouali M, Karou TG, Kruy SL, Soares JL, Mouffok F, Ravaonindrina N, Rasolofonirina N, Pham MT, Wouafo M, Catteau M, Mathiot C, Mauclere P, Rocourt J. Multicenter study of street foods in 13 towns on four continents by the food and environmental hygiene study group of the international network of Pasteur and associated institutes. Journal of Food Protection. 2002;65(1):146–152. [PubMed: 11808786]
  24. Henry FJ, Patwary Y, Huttly SR, Aziz KM. Bacterial contamination of weaning foods and drinking water in rural Bangladesh. Epidemiology and Infection. 1990;104(1):79–85. [PMC free article: PMC2271730] [PubMed: 2307187]
  25. Jerardo A.Import share of U.S. food consumption stable at 11 percent. 2003. [accessed February 1, 2007]. www​​/FAU/July02/FAU6601 .
  26. Koo D, Aragon A, Moscoso V, Gudiel M, Bietti L, Carrillo N, Chojoj J, Gordillo B, Cano F, Cameron DN, Wells JG, Bean NH, Tauxe RV. Epidemic cholera in Guatemala, 1993: transmission of a newly introduced epidemic strain by street vendors. Epidemiology and Infection. 1996;116(2):121–126. [PMC free article: PMC2271612] [PubMed: 8620902]
  27. Lantagne D, Quick R, Mintz ED. Household water treatment and safe storage options in developing countries: a review of current implementation practices. In: Parker M, Williams A, Youngblood C, editors. Water stories: expanding opportunities in small-scale water and sanitation projects. Washington, DC: Environmental Change and Security Program, Woodrow Wilson International Center; 2007.
  28. Lim-Quizon MC, Benabaye RM, White FM, Dayrit MM, White ME. Cholera in metropolitan Manila: foodborne transmission via street vendors. Bulletin of the World Health Organization. 1994;72(5):745–749. [PMC free article: PMC2486571] [PubMed: 7955024]
  29. Luby SP, Agboatwalla M, Painter J, Altaf A, Billhimer WL, Hoekstra RM. Effect of intensive handwashing promotion on childhood diarrhea in high-risk communities in Pakistan: a randomized controlled trial. Journal of the American Medical Association. 2004;291(21):2547–2554. [PubMed: 15173145]
  30. Luby SP, Agboatwalla M, Feikin DP, Billheimer W, Altaf A, Hoekstra RM. Effect of handwashing on child health: a randomized controlled trial. Lancet. 2005;366(9481):225–233. [PubMed: 16023513]
  31. Lule JR, Mermin J, Ekwaru J, Malamba S, Downing R, Ransom R, Nakanjako D, Wafula W, Hughes P, Bunnell R, Kaharuza F, Coutinho A, Kigozi A, Quick R. Effect of home based water chlorination and safe storage on diarrhea among persons with human immunodeficiency virus in Uganda. American Journal of Tropical Medicine and Hygiene. 2005;73(5):926–933. [PubMed: 16282305]
  32. Mahon BE, Sobel J, Townes JM, Mendoza C, Gudiel Lemus M, Cano F, Tauxe RV. Surveying vendors of street-vended food: a new methodology applied in two Guatemalan cities. Epidemiology and Infection. 1999;122(3):409–416. [PMC free article: PMC2809634] [PubMed: 10459643]
  33. Martorell R, Habicht JP, Yarbrough C, Lechtig A, Klein RE, Western KA. Acute morbidity and physical growth in rural Guatemalan children. American Journal of Diseases of Children. 1975;129(11):1296–1301. [PubMed: 1190161]
  34. Migele J, Ombeki S, Ayalo M, Biggerstaff M, Quick R. Diarrhea prevention in a Kenyan school through the use of a simple safe water and hygiene intervention. American Journal of Tropical Medicine and Hygiene. 2007;76 (2):351–353. [PubMed: 17297048]
  35. Mintz ED, Reiff FM, Tauxe RV. Safe water treatment and storage in the home: a practical new strategy to prevent waterborne disease. Journal of the American Medical Association. 1995;273(12):948–953. [PubMed: 7884954]
  36. Mintz ED, Bartram J, Lochery P, Wegelin M. Not just a drop in the bucket: expanding access to point-of-use water treatment systems. American Journal of Public Health. 2001;91(10):1565–1570. [PMC free article: PMC1446826] [PubMed: 11574307]
  37. Moe CL, Rheingans R. Global challenges in water, sanitation and health. Journal of Water and Health. 2006;4(Suppl 1):41–57. [PubMed: 16493899]
  38. Motarjemi Y, Kaferstein F, Moy G, Quevedo F. Contaminated weaning food: a major risk factor for diarrhoea and associated malnutrition. Bulletin of the World Health Organization. 1993;71(1):79–92. [PMC free article: PMC2393433] [PubMed: 8440042]
  39. Naimi TS, Wicklund JH, Olsen SJ, Krause G, Wells JG, Bartkus JM, Boxrus DJ, Sullivan M, Kassenborg H, Besser JM, Mintz ED, Osterholm MT, Hedberg CW. Concurrent outbreaks of Shigella sonnei and enterotoxigenic Escherichia coli associated with parsley: implications for surveillance and control of foodborne illness. Journal of Food Protection. 2003;66(4):535–541. [PubMed: 12696674]
  40. O’Reilly CE, Freeman MC, Ravani M, Migele J, Mwaki A, Ayalo M, Ombeki S, Hoekstra RM, Quick R. 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. Epidemiology and Infection. 2008;136(1):80–91. [PMC free article: PMC2870759] [PubMed: 17306051]
  41. PAHO (Pan American Health Organization) Health situation in the americas: basic indicators 2008. 2008. [accessed February 15, 2009]. http://www​​/topics/paho2008healthstats​/en/index.html .
  42. Parker AA, Stephenson R, Riley PL, Ombeki S, Komolleh C, Sibley L, Quick R. Sustained high levels of stored drinking water treatment and retention of hand-washing knowledge in rural Kenyan households following a clinic-based intervention. Epidemiology and Infection. 2006;134(5):1029–1036. [PMC free article: PMC2870483] [PubMed: 16438747]
  43. Penteado AL, Eblen BS, Miller AJ. Evidence of Salmonella internalization into fresh mangos during simulated postharvest insect disinfestation procedures. Journal of Food Protection. 2004;67(1):181–184. [PubMed: 14717371]
  44. Ries AA, Vugia DJ, Beingolea L, Palacios AM, Vasquez E, Wells JG, Garcia Baca N, Swerdlow DL, Pollack M, Bean NH. Cholera in Piura, Peru: a modern urban epidemic. Journal of Infectious Diseases. 1992;166(6):1429–1433. [PubMed: 1431259]
  45. Rosenau MJ. Preventative medicine and hygiene. New York: D. Appleton and Company; 1928. p. 111.
  46. Semmelweis I. Etiology, concept and prophylaxis of childbed fever (1861) Madison, WI: University of Wiscons; 1983. in Press.
  47. Sepulveda J, Bustreao F, Tapia R, Rivera J, Lozano R, Olaiz G, Partida V, Garcia-Garcia L, Valdespino JL. Improvement of child survival in Mexico: the diagonal approach. Lancet. 2006;368(9551):2017–2027. [PubMed: 17141709]
  48. Sheth AN, Russo E, Menon M, Kudzala AC, Kelly JD, Weinger M, Sebunya K, Masuku H, Wannemuehler K, Quick R.Successful promotion of water treatment and hand hygiene through a pilot clinic-based intervention for pregnant women seeking antenatal care-Malawi, May 2007-March 2008, Abstract #16. 57th Annual Conference, American Society for Tropical Medicine and Hygiene; New Orleans. December 7–11, 2008; 2008.
  49. Sivapalasingam S, Barrett E, Kimura A, Van Duyne MS, De Witt W, Ying M, Frisch A, Phan Q, Gould E, Shillam P, Reddy V, Cooper T, Hoekstra M, Higgins C, Sanders JP, Tauxe RV, Slutsker L. A multistate outbreak of Salmonella enterica serotype Newport infections linked to mango consumption: impact of a water-dip disinfestation technology. Clinical Infectious Diseases. 2003;37(12):1585–1590. [PubMed: 14689335]
  50. Sobel J, Mahon B, Mendoza CE, Passaro D, Cano F, Baier K, Racioppi F, Hutwagner L, Mintz E. Reduction of fecal contamination of street-vended beverages in Guatemala by a simple system for water purification and storage, handwashing, and beverage storage. American Journal of Tropical Medicine and Hygiene. 1998;59(3):380–387. [PubMed: 9749629]
  51. Swerdlow DL, Mintz ED, Rodriguez M, Tejada E, Ocampo C, Espejo L, Greene KD, Saldana W, Seminario L, Tauxe RV, Wells JG, Bean NH, Ries AA, Pollack M, Vertiz B, Blake PA. Waterborne transmission of epidemic cholera in Trujillo, Peru: lessons for a continent at risk. Lancet. 1992;340(8810):28–32. [PubMed: 1351608]
  52. Tauxe RV, O’Brien SJ, Kirk M. Outbreaks of food-borne diseases related to the international food trade. In: Doyle M, Erickson M, editors. Imported foods: microbial issues and challenges. Washington, DC: American Society for Microbiology Press; 2008.
  53. UNDP (United Nations Development Programme) Goal 4: reduce child mortality. 2009a. [accessed February 24, 2009]. http://www​ .
  54. UNDP (United Nations Development Programme) Goal 7: ensure environmental sustainability. 2009b. [accessed February 24, 2009]. http://www​ .
  55. Vollaard AM, Ali S, van Asten HA, Ismid IS, Widjaja S, Visser LG, Surjadi Ch, van Dissel JT. Risk factors for transmission of foodborne illness in restaurants and street vendors in Jakarta, Indonesia. Epidemiology and Infection. 2004a;132(5):863–872. [PMC free article: PMC2870173] [PubMed: 15473149]
  56. Vollaard AM, Ali S, van Asten HA, Widjaja S, Visser LG, Surjadi C, van Dissel JT. Risk factors for typhoid and paratyphoid fever in Jakarta, Indonesia. Journal of the American Medical Association. 2004b;291(21):2607–2615. [PubMed: 15173152]
  57. Wheeler C, Vogt TM, Armstrong GL, Vaughan G, Weltman A, Nainan O, Dato V, Xia G, Waller K, Amon J, Lee TM, Highbaugh-Battle A, Hembree C, Evenson S, Ruta MA, Williams IT, Fiore AE, Bell BP. An outbreak of hepatitis A associated with green onions. New England Journal of Medicine. 2005;353(9):890–897. [PubMed: 16135833]
  58. WHO (World Health Organization) World health statistics 2008. 2008. [accessed February 15, 2009]. http://www​​/whostat/EN_WHS08_Table1_Mort.pdf .
  59. Wright J, Gundry S, Conroy R. Household drinking water in developing countries: a systematic review of microbiological contamination between source and point-of-use. Tropical Medicine and International Health. 2004;9(1):106–117. [PubMed: 14728614]



Vice President, Health Programs.


Population estimated at 85.2 million as of June 2009 (CIA, 2009a).


Population estimated at 23.8 million as of June 2009 (CIA, 2009b).


Ross Professor of Tropical Hygiene Emeritus.


The findings and conclusions in this publication are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.


Corresponding author. Deputy Director, Division of Foodborne, Bacterial and Mycotic Diseases (DFBMD), National Center for Zoonotic, Vector-borne and Enteric Diseases (NCZVED), 1600 Clifton Road, Mailstop C-09, Atlanta, Georgia 30333; E-mail: vog.cdc@1tvr; Tel: 404-639-3818; Fax: 404-639-2577.


Enteric Disease Epidemiology Branch, DFBMD, NCZVED, CDC.


Leader, Diarrheal Diseases Team, Enteric Disease Epidemiology Branch, DFBMD, NCZVED, CDC.


Reduce by two-thirds the mortality rate among children under five (UNDP, 2009a).


Target 7a: Integrate the principles of sustainable development into country policies and programmes; reverse loss of environmental resources; Target 7b: Reduce biodiversity loss, achieving, by 2010, a significant reduction in the rate of loss; Target 7c: Reduce by half the proportion of people without sustainable access to safe drinking water and basic sanitation; Target 7d: Achieve significant improvement in lives of at least 100 million slum dwellers, by 2020 (UNDP, 2009b).

Copyright © 2009, National Academy of Sciences.
Bookshelf ID: NBK28455


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