The main, or central, idea of the passage is Rita Colwell discovered that filters made from saris could reduce the risk of cholera. How does the detail in bold develop the main idea?
Cholera is a deadly disease caused by the consumption of bacteria-laden water. In areas where sanitation is poor and clean water is scarce, cholera outbreaks occur regularly. In 2003, microbiologist Rita Colwell discovered a surprisingly simple and effective way of preventing some of these outbreaks. She and her team found that the bacteria that cause cholera attach to organisms called copepods, which flourish in standing water, such as ponds. If the copepods are removed from the water, many of the cholera bacteria will be removed as well. Copepod removal is relatively easy; it can be achieved by filtering the water through cloth. While working in Bangladesh, Colwell found that the cloth used for saris, traditional dresses worn by Bangladeshi women, worked particularly well for filtration. Colwell's team published a study showing that the use of sari filters reduced the incidence of cholera in rural areas of Bangladesh by approximately fifty percent.