Rita Colwell explores cholera and climate change in School of Public Health lecture

The UW School of Public Health and the department of environmental & occupational health sciences hosted their annual Omenn Lecture on April 17. The event featured Rita Colwell who gave a lecture titled “Oceans, climate and health: The cholera model.”

Colwell served as the 11th director and first female director of the National Science Foundation from 1998 to 2004 and is now a professor at the University of Maryland. She has authored or co-authored 20 books and over 800 publications. She holds 63 honorary degrees. 

Colwell earned her Ph.D. in marine microbiology at UW in 1961. Since then, Colwell’s research has revolutionized the scientific community’s understanding of infectious diseases in the environment, particularly cholera.

Cholera is an infectious disease caused by the bacterium Vibrio cholerae and is spread through contaminated water and food. Infection can cause severe diarrhea and vomiting that results in dehydration and even death. Those most at risk are those living in areas with unsafe drinking water and poor sanitation. In 2023 there were over 500,000 cases of cholera worldwide, and over 4,000 deaths.

Colwell opened her speech by informing the audience that, during COVID-19, the world was actually undergoing two pandemics. Particularly in developing countries, the seventh cholera pandemic was well underway. This pandemic has been a scourge for many populations around the world since 1961.

“Pandemics, we can anticipate, will continue,” Colwell said. “It certainly is necessary for you workers here in the School of Public Health and all of us to make sure that vaccine research and vaccine development, distribution, and availability continues.”

When Colwell began her research in the 1960s, the accepted truth was that cholera was transmitted from person to person. In reality, as Colwell discovered, the hosts for cholera are zooplankton, especially copepods. However, this discovery was not seen as an acceptable hypothesis, and — as a woman — it was difficult for her to change minds in the medical community.

To settle this dispute, Colwell described leading a three-year filtration experiment in Bangladesh from 1999 to 2002. Researchers taught women who collected water in 65 villages to use sari cloth to filter it before consumption. That study provided sufficient evidence that filtration reduced the incidence of cholera by about 48%.

“I think that was the beginning of the acceptance that the plankton were the vector, that the bacterium Vibrio cholerae does exist in the environment,” Colwell said. 

Later on, Colwell described how, in partnership with NASA, her team conducted a series of experiments that used satellite data to accurately predict the risk of cholera outbreaks. Through monitoring increases in plankton populations, the team was able to warn officials in several countries of impending outbreaks, giving them time to prepare.

The event was part of a series of lectures given in honor of Gilbert Omenn, who formerly served as the dean of the UW School of Public Health from 1982 to 1997. Omenn, who was present for the lecture, spoke positively of Colwell’s speech. 

“I thought it was a really important message,” Omenn said. “In all of our focus on environmental chemicals we sometimes forget about the microorganisms that are equally important. They’re a big challenge and you can do something about them.”

To end the lecture, Colwell gave dire warnings about how climate change is causing increases in the incidence of infection across bacteria species. She described a northern case limit that predicts the area where conditions allow for infection from Vibrio bacteria. This limit is shifting 50 meters upward annually as the temperature of the oceans rises, with the cholera species now being found off the coast of Florida.

“It is possible to predict that we are going to have our home-grown cholera outbreaks in the Gulf of Mexico,” Colwell said. “We need to be alerted to the potential of this.” 

Reach reporter Rowan Jackson at science@dailyuw.com. X: @Rowan_P_Jackson. Bluesky: @rowan-p-jackson

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