Harvard Public Health Review Winter 2007
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The lessons of oral rehydration therapy--The co-discoverer of a simple solution to a global killer passes all he has learned to public health's next generation

bangladeshi flood victim
TROUBLED WATERS Diarrheal diseases are rampant wherever humans encounter sewage-born pathogens, including deadly E. coli, rotavirus, and vibrio cholerae, the cholera bacterium. In Bangladesh, where 147 million people inhabit an area smaller than Iowa, many lack clean water.

A pinch of salt, a fistful of sugar, a jug of clean water. The simple elixir known as oral rehydration solution (ORS)--recently ranked No. 2 in a British Medical Journal survey of greatest health advances of the last 150 years--has saved tens of millions of people from death by infectious diarrheal diseases since the early 1970s. At the cost of a few cents, almost anyone alert enough to swallow can survive cholera, which can kill a man in four hours by draining him dry.

In a landmark paper published in the Lancet in 1968, the Harvard School of Public Health's Richard Cash and his chief collaborator, David Nalin, reported the results of clinical trials in Bangladesh, then East Pakistan. In rigorous tests, they showed that this simple solution worked as well as sterile intravenous fluids, a scarce and costly option in the Third World. Though researchers at Harvard and elsewhere had worked out the principles behind oral rehydration in the 1950s, the pair, then U.S. Public Health Service physicians in their 20s, were the first to administer ORS clinically in a reliably effective way.

Richard Cash
BRINGING SCIENCE TO THE PEOPLE HSPH’s Richard Cash, a pioneer of lifesaving oral rehydration therapy, now trains researchers throughout the developing world. In January of 2007, Cash will receive the annual Prince Mahidol Award in public health from the King and Queen of Thailand, in Bangkok, sharing the honor with researchers David Nalin and Dilip Mahalanabis.

"Those were heady times," remembers Cash, a senior lecturer in the Department of Population and International Health at HSPH, sitting in his cluttered office next to a three-foot-high statue of Shitala, the Indian goddess of smallpox. "We thought, 'This is great! Everybody's going to use this, right? We can all go home now.' But everybody didn't use it."

To get ORS to the masses, he says, researchers faced huge obstacles: A medical culture that clung to IV therapy as superior to what they perceived as a primitive oral form; a very high prevalence of illiteracy, especially among women; and no way to distribute ORS packets to remote, roadless areas.

In a presentation to a group of India's health leaders last spring, Cash chronicled a 10-year effort to surmount those daunting hurdles, using ORS to drive home a point as relevant today as it was years ago. What low-income nations need most is not "parachute research" handed down from rich, industrialized countries, but assistance in building their capacity to do research at home, where the problems are.

"You can't sit here in the U.S., do your research, and expect your ideas to work a thousand miles away," Cash tells his students. "The questions you ask come from the environment you're in. You're much less likely to ask the right questions if you're not there."

With one foot in Boston, the other in South Asia, Cash practices what he preaches. Since 2000, he's been spending the Winter session with HSPH students in Kerala, India, home to a public health school where he has taught for nine years. Today, in tiny Bangladesh, he's helping to launch another such school--one he hopes will, like Harvard, become a training ground and research hub for students from all over the world.

40 Million rescued since 1978
In a cover story on October 16, 2006, the European edition of Time reported that oral rehydration therapy has rescued at least 40 million people from the grip of water- and sewage-born pathogens since its adoption by the World Health Organization (WHO) in 1978. Since then, WHO estimates, annual deaths worldwide among acute diarrhea's chief victims--children under age 5--have plummeted from 5 million to 1.9 million.

Why, then, does the illness still kill so many in developing countries worldwide every year?

The answer, Cash says, is anything but simple. One billion people lack clean water; more than 2.4 billion lack a basic toilet. Oral rehydration therapy is not a cure, only a means to hydrate tissues while the immune system battles bacteria or viruses. And promoting ORT presents unique challenges in every country--issues research can help address, Cash notes.

In Bangladesh, in 1971, 10 million people fled to neighboring India to escape civil war. Crowded into camps, they seemed doomed to perish from hunger and a massive cholera outbreak. But in a desperate, grand-scale test of ORT organized by Johns Hopkins researchers based in Calcutta, 95 percent of the refugees survived.

Here was dramatic proof that ORT worked in the field. Still, it took a 10-year campaign by the International Centre for Diarrhoeal Disease Research in Bangladesh (ICDDR,B) and the nongovernmental organization now known as BRAC to turn a scientific discovery into a home remedy. Beginning in 1980, BRAC sent an army of 10,000 female health workers into the Bengali countryside, where they taught ORT to 13 million illiterate mothers. Children, too, learned the ORS recipe through one-room schools set up by BRAC that today number 37,000. In time, this simple solution became part of the national lore. At least 75 percent of families use ORS to treat diarrhea, according to government surveys.

The lesson, Cash says, is that no matter the problem--diarrheal infections, HIV, malaria--answers must be tailored to cultural norms, values, and practices. By way of example, he points to tuberculosis. Because treatment for the disease takes at least six months, helping patients complete their therapy is a major challenge. To ensure compliance, villages in Bangladesh enlist volunteers to serve as coaches. Moreover, patients (or, if they are too poor, their communities) must pay a modest bond up front, which they get back only upon completing treatment. At that point, their coach also earns a small sum.

"You must peg the payment at a level people can afford, but make it high enough that they'll miss it if they fail to follow through," explains Cash. In the United States, he says, a strategy that relied on community support to ensure patients' compliance "would never fly, given our emphasis on privacy and personal freedoms. But in a culture where the community is important to one's survival and the need to control infectious diseases is extremely urgent, this strategy can work."

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Karin Kiewra is the associate director of development communications at HSPH and editor of the Review.

Photograph: REUTERS-Jayanta Shaw

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