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Training “Disease Detectives”

Medically reviewed by Susan Kerrigan, MD and Marianne Madsen on February 2, 2023

When an outbreak hits, a team of skilled scientists is often the first to identify it. These men and women hunt for invisible killers. They use the latest technology and analytic techniques. They also use good-old fashioned deduction. They are members of The Centers for Disease Control and Prevention’s Epidemic Intelligence Service (EIS). They are the “disease detectives.” 


These highly educated epidemiologists fly into hot spots across the U.S. and around the world. Their work is vital, because no matter how remote the source of an infectious outbreak, in our interconnected global society it represents a risk to everyone.


What Do EIS Investigators Do?


On the ground, EIS investigators interview patients. They uncover their recent whereabouts and determine who else they came in contact with. By creating this detailed contact tracking, they can determine who else has been exposed. As the CDC explains, “EIS officers serve on the front lines of public health, protecting Americans and the global community, while training under the guidance of seasoned mentors. When disease outbreaks or other public health threats emerge, EIS officers investigate, identify the cause, rapidly implement control measures, and collect evidence to recommend preventive actions.”


During the Korean War, Alexander Langmuir started the EIS to assess the threat of biological warfare. He pioneered what he called “shoe leather epidemiology.” He believed CDC investigators shouldn’t rely on second-hand info. They needed to go into the field, obtain their own data, and learn as much as they could about the local environment. This was the only way they could solve an outbreak or other crisis. 


Langmuir also believed EIS officers should learn in the field. Today just 10% of the two-year fellowship is devoted to classroom study, examining case studies, and e-learning. The rest is a combination of hands-on assignments and assessing real world events under the guidance of an experienced supervisor. As the CDC explains, “EIS fellows might work in assigned public health projects, deploy to a field site to provide epidemiological assistance for disease outbreaks, or provide disaster relief following natural and industrial events.”


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COVID-19 - Preventing Spread

COVID-19 - Preventing Spread

The History Of “Disease Detectives”


Soon after its founding, the EIS was sent to investigate a deadly mistake. By 1955, the new polio vaccine was credited with saving thousands of children. Then, inadvertently, it began killing them. Five children died from polio after receiving the vaccine. Others were crippled. Even more confounding, other children were getting polio after playing with the recently vaccinated. Five of them died as well. Surgeon General Leonard Scheele had Langmuir create a surveillance system. In just a few days, he and his investigators traced the vaccine to Cutter Laboratories in California. There they discovered that the plant had accidentally produced 120,000 doses of live polio virus instead of the safe inactive form. Because of EIS action, thousands of lives were saved. The quick action bolstered EIS’s reputation.


Since its founding, over 3,500 people have been trained as EIS investigators. The fellowship is highly selective. Many candidates have already earned doctorates or have extensive field experience. Every year the CDC recruits scientists, medical doctors, nurses, and even veterinarians. Every year, around 600 people apply online for the two-year fellowship. About 200 applicants are later invited to CDC headquarters in Atlanta for interviews. Around 70 are chosen for the program. Most go on to leadership roles at the CDC or work for state and local governments as health department directors, epidemiologists, or a variety of other public health roles. For forty years, the CDC has aided other countries developing their own two-year field epidemiology training programs. Today there are programs in over 60 countries around the world. 


Just a year before the COVID-19 outbreak, Rear Admiral Anne Schuchat spoke to National Public Radio about her time as a disease detective. Currently the assistant surgeon general of the United States Public Health Service, and director of the National Center for Immunization and Respiratory Diseases (NCIRD), she was an EIS investigator during the SARS outbreak of 2003. Over 100 other EIS investigators went to hot spots around the world. Centered mainly in Asia, SARS would infect over 8,000 and kill 800. Like COVID-19, it was a disease without a vaccine to prevent it or a medicine to treat it. Schuchat went to Beijing, a city of 14 million where schools and businesses were shut down and TV shows were being created specifically to entertain the people confined to their home. The work of the CDC helped curb the outbreak. The epidemic inspired the 2011 movie Contagion, and actress Kate Winslet modeled her role as a disease detective on Schuchat.


The CDC sends disease detectives at the request of state and local governments. They are able to bring a broader perspective to symptoms and infections that may be unfamiliar to health care pros with limited experience outside of their own countries. CDC investigators joined their counterparts in South Korea during the COVID-19 outbreak. Although the CDC asked to assist where the virus is believed to have begun, their request was denied. Despite their cooperation during the SARs epidemic 17 years ago, in early 2020 the Chinese government refused to allow the disease detectives into the country. CDC investigators were dismayed not only because they were unable to help during the initial outbreak but also because working with Chinese health experts could have improved the American response when COVID-19 reached the U.S.


Written by John Bankston

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