We were able to go back five years later with funding provided by the Thrasher Foundation and determine through interviews that between 60% and 70% were still filtering. Most were using the technique we had introduced but we also found that control villages where we hadn’t instructed them to filter had actually begun to do so.
By analyzing the data, we discovered there was herd immunity. If you were a family that did not filter but you were surrounded by families who did, you were protected. This was because the transmission, person-to-person, was significantly reduced in that situation. We could say with great confidence that filtration played a major role in the reduction of cholera. The paper showing the herd effect and the sustainability of this initiative was published in the online Journal of the American Academy of Microbiology.
Rita Colwell on folding saris and saving lives
Saris are meant to be worn. But did you know that the garment can also be used to radically reduce the spread of cholera?
In 2003, environment microbiologist, scientific educator, and distinguished professor at the University of Maryland Rita Colwell conducted a study in which 7,000 women in Bangladesh were trained to filter the water they gathered every day through a cotton sari folded four times, which reduced the spread of cholera by almost 48%.