Wearing a Water Filter

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Water is something that's easy to take for granted, especially in a developed country where the taps run clean and clear. But the story is very different in the rest of the world, where nearly one billion individuals lack access to clean and safe water, and women and children can spend hours each day toting gallons of liquid from source to home.

Sometimes the solutions are simple, though. Back in 2003, University of Maryland microbiologist Rita Colwell and her colleagues reported that teaching women in villages in Bangladesh to filter water through folded sari cloth reduced the incidence of cholera by 48 percent. Cholera is caused by the bacterium Vibrio cholerae, which attaches itself to the gut of a tiny zooplankton that lives in standing freshwater. Untreated, the disease kills 60 to 80 percent of those infected and is especially hard on the elderly and children younger than 5. The sari fabric filters out the zooplankton and reduces exposure to the bacteria.

But what happened after the researchers left and the village women stopped getting lessons and reminders on water filtration? A new study, published in mBio, answers that question.

The researchers returned to Bangladesh and surveyed 7,000 women who had participated in the study five years earlier. The scientists found that 31 percent of the women continued to filter their water and that 60 percent of those women used sari cloth. In addition, 26 percent of women who had been in the control group and not received any education about water filtration were now filtering their water. Fewer people were hospitalized for cholera over those five years, and even households that did not filter their water had a lower incidence of the disease if they lived among many people who had continued the practice.

But many of the women who used the sari filters used less than four layers of cloth, which could reduce their effectiveness. And the researchers witnessed only a few women actually using the sari cloth during the hours of observation in the follow-up study.

So, although the method works and many of the villagers continued to use it without reminders, Colwell suggests that "active reinforcement" would likely be needed to ensure the higher protection level seen in the earlier pilot study.

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