I went to the National Association of Biology Teachers (NABT) Professional Development Conference in Atlanta, GA this year and it was great! My husband tagged along and explored the city on the MARTA train while I went to the conference, and we stayed an extra night so that we could see the botanical gardens and the Martin Luther King Jr. National Historic Site. I’m finally getting around to blogging about some of my favorite sessions, so this will be the first in a series of posts.
Rita R. Colwell, Ph.D., was one of the keynote speakers. Dr. Colwell is a professor and a former director of NSF, and her talk focused on the biology and ecology of Vibrio cholerae and how we can predict outbreaks of cholera. Apparently Vibrio cholerae and other Vibrio species are often symbiotic with copepods, and can be endemic to estuarine areas where these copepods live regardless of whether they are causing human infections. Traditionally, people have thought of Bangladesh as the native range of V. cholerae, but it probably occurs elsewhere, and they have found similar Vibrio species off the coast of Iceland and in deep sea areas near the U.S. gulf coast.
The copepods eat zooplankton, which are dependent on phytoplankton, which bloom when temperatures are warm. Based on this information as well as some other factors, Dr. Colwell and colleagues built a model predicting that cholera outbreaks would be most likely when events such as large festivals put a strain on sewer systems following periods of warm weather. Graphs showed that the model matched actual outbreaks quite well. It’s now even possible to use satellite data to predict outbreaks because the color of the ocean changes during phytoplankton blooms.
The recent outbreak of cholera in Haiti coincided with the highest temperatures in 60 years. In addition, the earthquake stirred up soil that led to the rivers in Haiti having a slightly basic pH, and in the lab, a pH of 8 is used to isolate V. cholerae from other species.
Dr. Colwell’s talk was extensive, and included data about the genetics of cholera, how genes that cause virulence in human disease are actually beneficial to copepods, high frequencies of multiple pathogens in cholera patients, reducing cholera incidence by filtering water through sari cloth in India, etc. I am definitely going to have to look up some of her papers.