Date Published: November 9, 2010
Publisher: Public Library of Science
Author(s): Jamie Bartram, Sandy Cairncross
Abstract: As the first article in a four-part PLoS Medicine series on water and sanitation, Jamie Bartram and Sandy Cairncross argue that the massive burden of ill health associated with poor hygiene, sanitation, and water supply demands more attention from health professionals and policymakers.
Partial Text: This is the introductory article in a four-part PLoS Medicine series on water and sanitation.
Globally, around 2.4 million deaths (4.2% of all deaths)  could be prevented annually if everyone practised appropriate hygiene and had good, reliable sanitation and drinking water. These deaths are mostly of children in developing countries from diarrhoea and subsequent malnutrition, and from other diseases attributable to malnutrition.
While rarely discussed alongside the “big three” attention-seekers of the international public health community—HIV/AIDS, tuberculosis, and malaria—one disease alone kills more young children each year than all three combined. It is diarrhoea , and the key to its control is hygiene, sanitation, and water (HSW).
Figure 2 shows the average reductions in diarrhoea incidence found to be associated with HSW interventions in several literature reviews. The impact of “real world” interventions varies widely in response to local factors such as which pathogens are contributing to disease and the relative contribution of different transmission routes.
Environmentally caused mortality and malnutrition have substantial economic costs. In Ghana and Pakistan, for example, the indirect effect on child mortality of environmental risk factors mediated by malnutrition adds more than 40% to the cost of directly caused child mortality (Figure 4) . If one takes into account the effect of such malnutrition on impaired school performance and delayed entry into the labour market, the cost doubles to 9% of gross domestic product (GDP). With the possible exceptions of malaria and HIV/AIDS in Africa, it is hard to think of another health problem so prejudicial to household and national economic development.
In 2000, world Heads of State signed the Millennium Declaration, a global pact to reduce poverty. The associated Millennium Development Goals (MDGs) provide the policy framework and global benchmarks for this challenge.
The impacts of poor HSW are not restricted to the developing world. Take the example of hand washing, which reveals an inappropriate level of complacency concerning hygiene in developed nations. Two intervention studies of hand washing with soap conducted in child-care centres in the US  and Australia  found reductions in diarrhoea of roughly 50%, similar to the reductions found in developing countries . In another study, carers of young children in the UK washed their hands with soap after changing nappies on only 42% of occasions .
The many non-health benefits mentioned above mean that the health sector is not alone in its interest in HSW. In practice, the main investments in HSW are made by ministries of water or education, by local governments and urban utilities, and by households themselves, which provide the opportunity for the health sector to influence large-scale deployment of resources for health.
Health evidence confirms that the burden of disease associated with inadequate HSW is overwhelmingly (although not exclusively) carried by the poor and disadvantaged in the developing world and is a major contributor to the cycle of poverty. Stated this way, HSW are problems.