Alum of the Month

Alum of the Month
  • August 2014: Barbara E. Mahon '78

    Barbara E. Mahon ’78 is a senior physician-epidemiologist at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia. The focus of her work is tracking diseases transmitted through contaminated food and water, like Salmonella and E. coli infection, cholera, typhoid, and botulism.

    After graduating magna cum laude in biology from Harvard in 1982, Mahon was awarded a one-year fellowship to study women’s sports in Africa. Though she enjoyed science, Mahon was still undecided about her career path, but her travel to Kenya, Tanzania, Uganda, Zimbabwe, and Sudan proved to be pivotal. “I was struck by all of the health problems and the huge challenges to public health. I had the chance to travel to Southern Sudan, which had recently opened to visitors after 17 years of civil war and isolation. It was a time of relative peace there, but it was tough and remote. While I was there, a family brought their veiled 8-year-old daughter to see me, thinking maybe I was a doctor and could help. When they lifted the veil, the child’s eye was in terrible shape—swollen, red, and weeping. I could do nothing to help. I wanted to learn medicine so that I could do something to make a difference.”

    Returning to the states, Mahon received her M.D. from the University of California, San Francisco. She trained first in pediatrics and then in epidemiology, receiving her master’s from the UC Berkeley School of Public Health. In 1994, she entered CDC’s “disease detective” training program, the Epidemic Intelligence Service, where she investigated outbreaks and did other field investigations. After that training, she worked in academic pediatrics and epidemiology, seeing patients, doing research, and teaching. “I found myself in different places at different times for different reasons, which enabled me to study and learn about different areas of infectious disease. When I was an assistant professor at the Indiana University School of Medicine, there was a very strong group doing research on sexually transmitted diseases, so I worked with them and studied STDs during pregnancy and their impact on newborns. When I moved to the Boston University School of Public Health, I focused on vaccine-preventable diseases.” In 2009, Mahon returned to the Centers for Disease Control in the Enteric Diseases Epidemiology Branch, becoming deputy chief in 2011.

    In her position at CDC, Mahon works in a variety of roles, including the training and supervision of others in an underlying quest to keep food and water safe for the public. She notes, “We track diseases in part so that we can detect outbreaks and ask questions like, ‘What specific events led to this outbreak, and how can we prevent those events from happening again?’ Outbreaks make up only a small fraction of the illnesses, but they give us important clues about the foods and other exposures that are making people sick. Salmonella is a good example—it can contaminate almost any food, so what are the most important foods that are making people sick? The answers are not obvious without a large amount of data and careful analysis. My personal role is to provide guidance and to help formulate and define questions that will lead to useful answers. I spend a lot of time thinking about how to do studies and how to explain our results clearly.”

    Mahon was back in Kenya recently, where she led a team investigating antibiotic resistance in Salmonella in young children with bloodstream infections and meningitis. “In Africa the mortality rate for these kinds of infections is about 20 percent. The antibiotic resistant Salmonella is essentially untreatable with the antibiotics that are generally available in Kenya. This is a real concern, and it can spread fast. In the states, CDC is working with other agencies to address antibiotics resistances. It’s a complicated issue, and it’s a major threat and something I think we will all be hearing more about.”

    Although the pathogens she works on can be transmitted by many routes, the study of foodborne illness often takes precedence for Mahon. “There are about 1,000 reported foodborne outbreaks a year in the U.S., but many more go undetected, uninvestigated, or unreported. Multi-state outbreaks make the news, but they are the minority. Most outbreaks happen at the state or local level.” Mahon and her team received a CDC award for their emergency response work on the 2011 Listeria outbreak from cantaloupes.

    What precautions does Mahon take personally to be safe? “It is interesting to have a potluck with my group. Really, the risk for serious foodborne illness is fairly low in healthy people, and I am probably no more careful with food preparation than the average person who keeps a clean kitchen. But when I serve older or sick people or infants, who are at a higher risk, I am very careful. I worry about people drinking raw milk. There is really good reason to pasteurize milk.”

    Beyond concern about antibiotic resistance, Mahon worries most about the flu. “I think of all the infectious diseases, I am most scared of the flu and other respiratory viruses like SARS and MERS. We were lucky that the last flu pandemic wasn’t worse. In the 2009-2010 season, pregnant women were hit hard. But that virus wasn’t nearly as bad as the flu of 1918, when somewhere between 50 and 100 million people died. It was one of the most devastating epidemics in history.”

    As for Hotchkiss, Mahon says, “My class is very close. When I look at what my classmates have done and are doing out in the world, I see an amazing range of interesting and valuable contributions. Personally, I learned how to apply myself to an intellectual challenge at Hotchkiss, and that it feels good to work hard. I spent a lot of time writing, which has definitely been useful in everything I have done in my career. When I took Biology 350 with Jim Morrill, it clicked - he was a very important teacher for me. I think when I was at Hotchkiss, there was a bit of a bias toward careers in business and law, but that seems to be changing, and that’s good. I’d like to see more people involved in science.”

    To learn more, please visit:

    CDC food safety page
    CDC raw milk page
    CDC antibiotic resistance threats report

    Posted August 1, 2014

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