Cholera infects 100,000 people annually, so when Dr. Rita Colwell told an audience at the September 2007 Café Scientifique that she convinced Bangladeshi women to use folded sari cloth from their old dresses to prevent cholera, listeners were impressed. After all, cholera epidemics in third world countries result from contaminated water that can be purified with million-dollar treatment plants. 

Colwell’s sari solution, however, cut incidence of the waterborne disease in half among participating Bangladesh villages along the Ganges River during Colwell’s study. 

Colwell spoke to an audience of about 125 community members and guests at the Big Sky Ski and Summer Resort, at MT INBRE’s Northern Rocky Mountain Conference on Infectious Disease and Environmental Health.

During Colwell’s tenure as the 11th Director of the National Science Foundation from 1998 to 2004, she focused on K-12 science and mathematics education, graduate science and engineering education and increased participation of women and minorities in science and engineering. She currently chairs Canon U.S. Life Sciences, Inc. and serves as Distinguished University Professor at both the University of Maryland at College Park and Johns Hopkins University Bloomberg School of Public Health.

Colwell told the Café audience that it was during her many studies of cholera epidemics that she hypothesized that Vibrio cholerae had a symbiotic relationship with plankton, which thrive during warm surface water conditions found as a result of El Niño weather systems, and in the future as a result of global warming.

“Perhaps this would explain the peculiarities of massive cholera outbreaks some years and some years not,” she said, noting that she encountered “a major surprise during a dive off the coast of Oregon in a submarine.” She was astonished to find copepods—a warm-water organism—existing in the deep sea around sea-floor thermal vents.

“We confirmed the existence of Vibrio cholerae on the sea floor that has two chromosomes,” she said. Her team of scientists traced the chemistry of the organism and found that it correlated to a phytoplankton bloom occurring during surface water’s warming.

“The zooplankton—the miniature cattle of the sea that eat phytoplankton—that’s where cholera epidemics occur,” the aquatic microbiologist explained. The cholera bacterium lives in the gut of the zooplankton microscopic aquatic animals.

By employing satellite imaging of sea surface temperatures and overlaying the resulting temperature maps to maps delineating cholera epidemics, Colwell found that during the warmest years, the worst epidemics occurred. Her team was able to accurately forecast how many people would contract cholera on a given day through temperature maps and phytoplankton bloom.

While Colwell’s high-tech surveys allowed modeling to predict the conditions conducive to cholera epidemics, it was a low-tech solution that may have saved a large number of people in rural villages of Bangladesh. 

“We tested a variety of cloth to filter untreated water,” she explained. “We tested t-shirts, Chinese poplin and sari, the cloth women use in dresses. We found that old sari, folded four or five times gave them a 20 micro filter. We reduced cholera by 50 percent that year. We think we can build a predictive model for cholera around the world.”

Colwell’s message carried with it an alert that while there’s good news, the bad news is that infectious disease will be on the rise due to global warming when some water-borne infectious diseases may become more virulent. It is highly feasible, she said, for public health in the 21st century to employ her modeling approach with equally good success for many if not most infectious diseases.

“Unless you are a member of the Flat Earth Society, you accept the facts of global warming,” she said. “When that occurs, 17 to 20 percent of lands are affected by a sea- level rise of one meter. There is no hiding from climate change.”

 

The Café Scientifique was co-sponsored by Montana INBRE and Montana State University COBRE programs.