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International Journal of Infectious Diseases: Volume 4, Number 1
Safe Drinking Water: An Attainable Goal, Key to Health and Development, Appears Farther Away
Richard L. Guerrant, MD; Sean R. Moore, MS; and Aldo A. M. Lima, MD, PhD

The article in this issue entitled "Limited Effectiveness of Home Drinking Water Purification Efforts in Karachi, Pakistan," by Luby et al, is a reminder that a readily attainable, highly cost-effective goal of safe drinking water seems ever farther from reach. This, despite the increasing recognition of the threats it poses not only to the fastest growing majority living in poverty around the world, but also to affluent travellers and consumers of the increasingly global food supply. The health benefits of improved water availability and sanitary facilities has been well recognized since the time of John Snow's interruption of the cholera epidemic in London in the 1850s.1-4 Effects of improved water supplies and sanitation range from a 21 to 30% reduction in diarrhea rates to adequate water and sanitation being a critical, necessary improvement to a much greater "multiplier effect" that enables other interventions, such as sanitation, handwashing, education, vaccines, etc., to effect their maximal benefit.2-4

Despite impressive attempts at boiling and filtering water in the homes, Luby et al emphasize the complexity of obtaining effectively safe drinking water, which often is contaminated and may not reduce risk of waterborne disease. Water quantity and availability may be even more important than water quality.2,3 Luby et al found that water supplies were severely limited and only intermittently available. Recontamination, which can be prevented by narrow-neck storage vessels,5 may have occurred in the Karachi study, as the authors acknowledge. The importance of residual antibacterial activity, such as chlorine, repeatedly has been shown.5,6 A study of home chlorination in northeast Brazil, with no change in diarrhea rates despite effective reductions in coliform contamination, showed that education and behavior modification (i.e., use of chlorinated water for drinking) are required for technologic advances to exert their benefit.6 Finally, the complexity of synergistic effects of improved sanitation may limit the benefits seen with a single change, such as transient water treatment, as by boiling or filtration.

Remarkably, despite the attainability of safe water with current resources, the ancient scourges of life-threatening waterborne diseases like typhoid fever and cholera continue, and many, like cholera, are worse than ever at the end of the twentieth century. This is repeatedly demonstrated with social disruption causing epidemics of cholera and shigellosis, with over 50,000 deaths in Rwanda in July 1994,7 nearly 9000 cases of typhoid fever with 95 deaths in Tajikistan, in 1997,8 and interrupted water supplies in Albania and Romania and other areas, which are affecting one in seven of Europe's 870 million people in 1999.9 Even life-saving oral rehydration solutions can be sources of pathogens multiplying to potentially dangerous levels.10-13

Nevertheless, adequate water availability and sanitary facilities do work; witness reductions in enteric diseases throughout developed areas and the complete absence of any secondary cases of cholera, despite the importation of 31 cases from an airline arriving in Los Angeles from Peru in 1992.1,14,15 A key problem noted by Luby et al is also the perception that things are better than they actually are. They note that, despite the United Nations estimate that 96% of persons living in urban Pakistan have access to safe water, only 16% of Karachi households in their study had clean water. Furthermore, organisms such as Cryptosporidium are highly resistant to chlorination and pose threats even in highly developed areas, as illustrated by the Milwaukee outbreak.16 Accurate information is key to solving the problems of safe drinking water for all. Future studies of cost effectiveness of interventions to provide safe drinking water should address not only quality, but also quantity, availability, storage, residual antimicrobial effects, patterns of use behavior, and sanitary facilities, as well as seasonal household contamination and methodologic details.

As with geohelminthic infections, the threat of enteric infections to children in poverty may well be far greater and long lasting on child development and physical and mental functional capacity than previously appreciated.17-20 Perhaps armed with this information researchers can begin to invest in the long overdue means to control these devastating infections as a global imperative to development on which all ultimately depend.

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