By Mark Shwartz

Each year, diarrhea kills an estimated 1.8 million people worldwide. More than 90 percent of the victims are children younger than 5 in developing countries. What makes the problem especially tragic is that it seems so preventable. Diarrhea usually results from drinking water contaminated with human feces, coming in contact with a person with poor personal hygiene, or exposure to a contaminated surface. About 1 billion people lack access to adequate freshwater supplies, and approximately 2.8 billion do not have access to basic sanitation, so the problem is particularly daunting. 

Enter Jenna Davis and Ali Boehm from the Stanford School of Engineering. In 2006, Davis (an authority on sanitation in the developing world) and Boehm (an expert on microbial contamination in freshwater and coastal environments) were awarded an Environmental Venture Projects grant (EVP) to find solutions to the problem of diarrhea-related deaths among children in Africa. The research team includes Gary Schoolnik, a professor of medicine internationally recognized for his work on infectious diseases; Abby King, a professor of epidemiology; and Cynthia Castro, a research associate at the Stanford School of Medicine. 

The focus of the EVP study is Dar es Salaam, the largest city in Tanzania. Historically, residents of the peri-urban communities surrounding Dar have relied on water from surface sources or shallow wells that are in close proximity to household pit latrines. "That means when people defecate, the waste stays under the house," said Davis, an assistant professor of civil and environmental engineering and a Woods Institute fellow. "As a result, those shallow wells are very vulnerable to microbial contamination." 

To address the situation, city water and sanitation officials have drilled a series of borewells that tap into clean aquifers deep below the surface. High-quality water is then pumped into storage tanks connected to sets of four to six taps. "Most of the water from the borewells meets the World Health Organization guidelines for E. coli bacteria in drinking water," said Boehm, an assistant professor of civil and environmental engineering. "Concentrations are typically less than 1 bacterium per 100 milliliters water." 

For a little money, residents can go to the taps and carry clean water back to their homes. By and large, people use the borewell water for cooking and drinking. But so far, there has been little improvement in their overall health. City water officials want to know why and have turned to the Stanford team for answers. 

Household surveys 

In summer 2008, Davis, Boehm, and a team of students and post-graduates traveled to Dar to study 300 households over a 10-week period. The research team hired Tanzanian enumerators to conduct surveys and interact directly with the households. The enumerators visited each household four times. On the first visit, they collected behavioral information, primarily from female heads of households ("the mothers"), and tested stored water and the hands of family members for indicators of fecal contamination.    

Approximately 7,000 water and hand samples were collected during the study. Laboratory analysis revealed very high levels of bacterial contamination on the hands and in the stored drinking water of study participants, even though the deep borewell water collected at the source was generally of good quality.       

 "There appears to be something in the transport and storage that is contaminating the water," Davis explained. "It's probably happening when people use their fecal-contaminated hands to scoop water out of their home containers. Another possibility is that the stored water containers used for fetching water are not cleaned regularly."      

A major challenge facing each household is distance. Some homes are 200 yards from clean tap water, and a typical water container weighs 44 pounds when full. "We know that when people haul water from a distance, the first thing they do is drink it, then they cook, and then they wash their kids, themselves, and sometimes their animals," Davis said. "So they may not have enough water for adequate personal hygiene." 

For the second round of visits, the researchers separated the households into four groups. Each group was given generic information about how germs are spread through the five F's-feces, flies, field, food, and fingers. "We used pictures showing several ways to prevent the spread of germs, such as handwashing at critical times and protecting the quality of stored water," Davis explained. "One of the four groups received only the generic information. A second cohort got the generic information plus the results of their water test. The third cohort got the generic information and their hand test results. The fourth group got everything-generic information, the water test results, and the hand test results. The idea builds on basic health behavior-change theory: The more tailored and less generic the message is, the more effective it should be at motivating change." 

'More is not better' 

The preliminary results were surprising. Groups that received hand data or water data alone seemed to have a more positive response than the households that got both hand and water test results. "It turns out that more is not better," Davis said. "Even though we spent an equal amount of time discussing water-related strategies and hand hygiene-related strategies, there was a bigger behavioral change on the hand hygiene side than on the water side."     

In September 2008, she and her colleagues were awarded a three-year, National Science Foundation grant to expand the number of households and the length of the study. "We're aiming for a full year, which would allow us to monitor behaviors in both the dry and wet seasons," she said. Data collection will begin in mid-2009, and the results could lead to low-cost policy solutions that ultimately reduce the incidence of diarrhea for tens of millions of children in sub-Saharan Africa and throughout the developing world.     

None of this would have been possible without the initial EVP grant, according to the researchers. "I would never have had the opportunity to expand my work on pathogens in coastal waters to pathogens in drinking water without the EVP award," Boehm said.       

"There was no project in Africa before we had the EVP," Davis added. "It was the glue that brought Abby King into a conversation with Ali Boehm and me. In that conversation, we realized that we had an opportunity to incorporate health behavior change into the study. The EVP really got us rolling by encouraging this broader dialogue and broader thinking."