Rita Colwell: satellite early-warning, plankton link and simple cloth filtration cut cholera in Bangladesh

Rita Colwell, former director of the National Science Foundation and a microbiologist who has led long-term cholera studies, told attendees at a presidential lecture series that cholera is closely tied to environmental conditions and can be predicted months in advance by satellite measurements of sea-surface temperature, chlorophyll and sea-surface height.

Colwell said the bacterium that causes cholera, Vibrio cholerae, lives year-round in coastal and estuarine waters and attaches to small crustacean plankton called copepods. She described a predictive model that combines satellite data with ground measurements and historical hospital records in Bangladesh to forecast cholera peaks in the spring and fall. "We were able to predict months in advance," Colwell said, noting a test where the team estimated about 24 cases per thousand and later received ground counts of 25 to 26.

The model, Colwell said, links a chain of seasonal events: increased sunlight and warming of surface waters, a phytoplankton bloom followed by a zooplankton (copepod)…