Using sari cloth to filter water protects household from cholera: Study

A five-year follow up study in Bangladesh finds that women are literally wearing the answer to better health for themselves, their families and even their neighbors. Using the simple sari to filter household water protects not only the household from cholera, but reduces the incidence of disease in neighboring households that do not filter. The results of this study appear in the inaugural issue of mBio-, the first online, open-access journal published by the American Society for Microbiology (ASM).

"A simple method for filtering pond and river water to reduce the incidence of cholera, field tested in Matlab, Bangladesh, proved effective in reducing the incidence of cholera by 48 percent. This follow-up study conducted 5 years later showed that 31 percent of the village women continued to filter water for their households, with both an expected and an unexpected benefit," says Rita Colwell of the University of Maryland, College Park, a researcher on the study.

In 2003, Colwell and her colleagues reported the results of a field study that demonstrated by simply teaching village women responsible for collecting water to filter the water through folded cotton sari cloth, they could reduce the incidence of cholera in that group by nearly half. Though the results were promising at the time of the research, there was concern that the practice of sari water filtration would not be sustained in later years.

Five years later they conducted the follow-up study to determine whether sari water filtration continued to be practiced by the same population of participants and, if it were, whether there would continue to be a beneficial effect of reduced incidence of cholera.

Over 7,000 village women collecting water daily for their households in Bangladesh were selected from the same population used in the previous study. Survey data showed that 31 percent continued to filter their water, of which 60 percent used a sari. Additionally, they found that of the control group (the one that did not receive any education or training in the first study) 26 percent of households now filter their water.

"This is a clear indication of both compliance with instructions and the sustainability of the method, but it also shows the need for continuing education in the appropriate use and benefits of simple filtration," says Colwell.

The researchers also looked at the incidence of cholera in households during the 5-year follow-up period. While not statistically significant, they found the incidence of hospitalizations for cholera during that period reduced by 25 percent.

"With the lower rate of filtration in this follow-up study, it is not surprising that the observed reduction in disease rate was not as high as the 48 percent observed in the original trial, suggesting that active reinforcement would have been effective in ensuring higher protection," says Colwell.

They also found an indirect benefit. Households that did not filter their water but were located in neighborhoods where water filtration was regularly practiced by others also had a lower incidence of cholera.

"Results of the study showed that the practice of filtration not only was accepted and sustained by the villagers but also benefited those who filtered their water, as well as neighbors not filtering water for household use, in reducing the incidence of cholera," says Colwell.