A safe solution: disinfection at home could provide Africa with cheap and abundant potable water.
Sweating and thirsty from the equatorial heat, I take the beverage an event organizer offers me. I'm glad to see that it's a soft drink. Quick has told me more than I want to know about the microbes that flourish in the local water.
A few minutes later, in the grassy clearing that serves as their stage, two actresses face off against three actors who have identified themselves as Typhoid, Cholera, and Amoeba. As the men grimace menacingly, the women recite tips about how to disinfect drinking water. The skit ends when the pathogen impersonators collapse under the women's verbal onslaught.
The drama played out in this western Kenyan village may smack of comedy, but the performers are engaged in a deadly serious public health campaign. The chlorine-based system they're promoting for water treatment could save millions of lives, some researchers say. In areas where the inexpensive, low-tech method has been introduced, it has cut diarrhea rates and won adherents, and it's now poised for a rapid deployment throughout Kenya.
With epidemiological evidence that supports the system's effectiveness, its promoters are working to deliver it to many people. As a journalism fellow working with the CDC Foundation and sponsored by the John S. and James L. Knight Foundation, I saw that effort in action when I followed Quick last September some 10,000 miles from his headquarters at the Centers for Disease Control and Prevention (CDC) in Atlanta.
LET THEM DRINK COKE For many Kenyans, and for much of the world's population, microbe-contaminated drinking water is a fact of life and, all too often, death. Recent calculations suggest that waterborne infectious organisms cause billions of diarrhea illnesses worldwide and more than 2 million diarrhea-related deaths each year. Infants and children are the hardest hit. The World Health Organization estimates that most of these deaths could be prevented if all people had access to safe drinking water and adequate sanitation.
However, the international organization also figures that approximately 1.1 billion people around the globe rely on ponds, streams, and other exposed and untreated sources for their drinking water. Despite concerted international efforts to expand access to wells and municipal waterworks, the number of people drinking water from so-called unimproved sources has remained more or less the same since 1990.
In September 2000, the United Nations set a 15-year goal of providing improved water supplies to half the people who currently lack them. That ambitious target mandates that, not allowing for population growth, about 125,000 new people gain access to safe water every day between now and 2015, Quick notes.
That would solve only part of the problem. In addition to the people who use an unimproved water source, 1 billion or more with access to pumps, wells, or municipal water works also frequently drink microbe-contaminated water, estimates Steve Luby, Quick's colleague at the CDC. Many households in the developing world draw contaminated water from poorly maintained pipelines. Furthermore, Luby says, such municipal systems and other communal sources of running water often work only intermittently, so families store water in the home. The CDC has found that water can become contaminated during storage, especially when its container is a bucket or other wide-mouthed vessel into which people dip hands or cups.
"The ultimate good would be for everyone to be able to open a tap in their house and have clean water come out," says Sally Cowal, a vice president of Population Services International (PSI), a Washington, D.C.-based nonprofit group. It will take years to fund and build the required infrastructure in many parts of the world, she notes.
QUICK FIX That's why Quick and his colleagues are championing a low-tech, interim solution to enhance drinking-water quality--one that can be marketed cheaply on a large scale. Their approach, referred to as the Safe Water System (SWS), emphasizes disinfection at the places where water is consumed. The two physical components of SWS are a chlorine-based disinfection solution and a storage container that prevents recontamination.
The concept behind SWS began to take shape during a series of CDC missions in the early 1990s in response to outbreaks of cholera and other diarrheal diseases in Latin America and Africa. Quick, then a newcomer to the CDC, and his fellow disease investigators observed that people who used water-storage vessels with wide mouths were more likely to get diarrhea than neighbors using narrow-mouthed containers were. Quite simply, people were more likely to stick hands or potentially contaminated objects into containers with larger openings.
To stop this route of disease transmission, the investigators developed a 20-liter plastic vessel with a narrow mouth and a spigot. After filling this container, people can disinfect the water and store it with minimal chance of recontamination. They can also draw water from the vessel without the need to dip cups or ladles into it.
Where such vessels are unavailable, some people familiar with SWS have developed homegrown alternatives. For example, Kenyan pottery collectives now produce narrow-mouthed, spigot-equipped versions of traditional clay pots.
Such vessels represent a step toward storing water safely but don't address the challenge of cleaning water from a contaminated source. For that, Quick and his colleagues turned to sodium hypochlorite, the highly reactive bleach that disinfects swimming pools and municipal water supplies in developed nations.
In fact, chlorine-treated water can taste and smell a bit like typical swimming pool water--an aspect that some users find unappealing. "But most people don't find it objectionable" once they recognize its impact on health, says Robert Tauxe, who supervises the CDC branch that also employs Quick and Luby. "Some even identify it as the taste of safety," Tauxe says.
Collaborating with nongovernmental organizations, such as CARE, and chemical companies, the CDC scientists have been testing SWS since the mid-1990s. In trial after trial, people who use the chlorine solution and appropriate vessels to treat and store drinking water experience roughly half as much diarrhea as neighbors who don't use the system.
In a study conducted in Zambia and published in the May 2002 American Journal of Tropical Medicine and Hygiene, for example, Quick and his colleagues reported that households equipped with chlorine solution and a good storage vessel had significantly less Escherichia coli bacteria in their water and 48 percent less diarrhea than did households not using these tools. In other studies, even chlorine use in other storage vessels significantly reduced diarrhea rates and could be expected to save lives, Quick says.
SWS has earned some esteemed followers, including retired waterborne disease researcher Eugene J. Gangarosa, who calls it "a landmark development." Decades ago, Gangarosa contributed to the development of oral rehydration salts, a packaged blend of sugars and electrolytes that when mixed with water can prevent life-threatening dehydration in cholera victims. While that treatment is now credited with saving more than a million lives a year, "this new safe water system that CDC has developed has even greater potential" to prevent deaths from waterborne pathogens, Gangarosa says.
MILES TO GO Like many innovations with potential to improve public health, Quick's system must make the pitfall-fraught transition from the proof of concept to real-world implementation. The cost, accessibility, and acceptability of SWS all factor into how widespread it becomes.
Supporters of SWS are using mass media, from billboards to radio advertising, to supply and promote its water-purification tools through distribution channels already in use for other commercial products. "You can't just go community by community," says Quick. "You need some sort of mass production and mass distribution."
To that end, CDC recently reached an agreement with PSI, which already tends a network of kiosks in Kenya that sell condoms and insecticide-treated mosquito nets. Beginning this spring, PSI will also supply chlorine solution throughout the country. Each 33-cent bottle of the solution, branded WaterGuard, could last a typical Kenyan family several weeks.
Both organizations suggest that the partnership could have a rapid impact. PSI obtained funding to roll out a similar program in Malawi in southeastern Africa last September, and marketing of SWS was in full swing in that country by November, says PSI's Cowal.
Meanwhile, Quick is on the road much of the year, bouncing along decaying asphalt or dirt arteries on his way from one project site to the next. Malawi, Madagascar, Rwanda, and Zambia already have nationwide SWS programs, and Kenya is among 11 other countries in Africa, Asia, and Latin America with regional ventures. Afghanistan is scheduled to join that number this year.
SCENT OF ACCEPTANCE No matter how well a public health practice is designed, tested, and marketed, its potential impact is limited by how widely it's put to use.
With SWS, the powerful and immediate benefit--avoiding the common and sometimes lethal problem of diarrhea--appears to make an impression on people.
This seemed evident to me one morning in Tororo, Uganda, about 2 weeks after I encountered the dancing chlorine bottle in Ogongo. Quick and I had gathered with a team of research assistants working with him and the CDC on a study of SWS. This team was charged with monitoring diarrhea rates and collecting stool samples from area residents, half of whom had been provisioned with chlorine solution.
Few reports of diarrhea had been coming in, even from the residents who hadn't been given bottles of chlorine or SWS storage vessels. Quick quizzed the assistants in search of clues to understand why.
Some participants who initially complained of the taste of the treated water were now refusing to drink any water that didn't give off a telltale whiff of chlorine. They'd noticed a reduction in how frequently they had diarrhea and concluded that SWS was the answer. One worker recalled how a study participant carried along a personal supply of chlorine-treated water on a trip to a relative's funeral.
Then another worker shared an insight: Some residents receiving chlorine were sharing their treated water with people in the study's control group, who weren't supposed to receive the intervention until the study's end. The people in the latter group had apparently also noticed the beneficial effects of the treatment and availed themselves of it through their neighbors' generosity.
By blurring the line between people getting and not getting chlorine-treated water, the villagers' actions were confounding the data. But they also seemed to indicate that the SWS strategy had achieved acceptance among its most critical audience, its potential beneficiaries. By fostering that outcome, perhaps Quick's endeavor has already made the step from scientific study to public health program.
RELATED ARTICLE: Do-it-yourself.
A grab bag of water treatments
Heat, ultraviolet radiation, filtration, or some combination of these can disinfect water, just as chlorine can. A few researchers consider these alternatives safer because chlorine can react with organic material in murky water and produce organochlorine compounds, which carry cancer risks. That hazard has elicited hesitation among some health workers in countries where the Atlanta-based Centers for Disease Control and Prevention (CDC) is promoting chlorination. However, most researchers agree that any risks from chlorination byproducts over a lifetime of drinking treated water are more than compensated for in developing countries by the reduced risk of death from diarrheal diseases at an early age.
Straining water through a cloth or using some other method to remove sediments before adding chlorine mitigates the formation of potentially harmful byproducts and also reduces how much chlorine is required for treatment. Furthermore, according to a report by Rita R. Colwell and her colleagues in the Feb. 4 Proceedings of the National Academy of Sciences, cloth straining by itself can reduce cholera infections by 48 percent.
Some people use other low-tech disinfection methods to kill bacteria that can't be removed by straining water. Boiling kills pathogens, but fuels for heating often are too expensive or hard to obtain. Such fuels can also pose environmental and health risks.
Practitioners of solar disinfection put water into used soft-drink bottles or other clear containers--sometimes painted black on one side to improve heat absorption--and set them out in the sun. In strong sunlight, heat and ultraviolet radiation can render microbe-contaminated water potable in as little as 3 hours. Kenyan children who treated water this way suffered diarrhea 20 to 30 percent less often than did those who drank from bottles they left in the shade, Ronan M. Conroy and his colleagues at the Royal College of Surgeons in Dublin, Ireland, reported in 1996.
Filtering water through densely packed sand or storing it for several weeks also appears to improve water quality in certain conditions, says Conroy, but for many other alternatives in use, researchers "just don't have data on whether these things work."
Furthermore, such methods may purify water without preventing recontamination during storage, says CDC's Robert Tauxe. One advantage of chlorine is that some of the chemical remains in the water and continues to work as an antimicrobial agent. "If there is any recontamination, the chlorine will knock it out," says Tauxe.--B.H.
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|Date:||Mar 1, 2003|
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