Reduction of cholera in Bangladeshi villages by simple filtration.

Using old saris to filter drinking water from rivers and ponds has halved cholera cases in remote Bangladeshi villages. A 3 year study by US National Science Foundation found the best filtering is when the sari was folded so the water passes through 4 layers of cloth. In laboratory tests, this removed >99% of the cholera-causing bacteria. The bacteria cling to plankton that are too big to go through the fabric. The study showed that in practice this filtering reduces infections as the rate of new cholera cases in the 27 villages asked to filter water through saris was half that before the trial. Also encouraging was the villagers' response to the educational program, as once they were shown the bugs swimming around in the untreated water, they realised the importance of filtering. PNAS 2003;100:1051-1055.