The phone rings on the evening of Feb. 28, 2020.
“We need you to deploy to Seattle. Meet your team at Roybal tomorrow and additional details will be provided.”
For weeks, the Centers for Disease Control and Prevention had been tracking the spread of the novel coronavirus closely. The disease detectives of the Epidemic Intelligence Service (EIS) program were on alert, sitting by their phones anxiously awaiting “the call.” When the phone rang, imminent deployment followed. Within 24 hours, each team member called that night — including one of us, Eric Chow — had boarded a plane to Seattle. We had not yet realized that we would be investigating the first known outbreak of Covid-19 in the United States.
Over the past 75 years, the CDC’s EIS program has trained more than 4,300 people to be the next generation of public health leaders. While the program began as a response to the threat of biological warfare during the Korean War, it has evolved to become a critical part of CDC’s public health response structure, answering calls for public health emergencies in the U.S. and around the world.
In 1951, Alexander D. Langmuir, then chief epidemiologist at the CDC, led the creation of EIS with the goal of training a cadre of skilled epidemiologists ready to investigate the cause of disease, how it spreads, who it impacts, and, ultimately, how to prevent these health threats from hurting our communities.
In the years that followed, mirroring the growth and evolution of CDC focus areas, the EIS program expanded training to include infectious disease threats, animal illnesses, and noncommunicable disease subjects such as chronic disease, injuries, gun violence, substance use, worker safety, environmental toxins, and more.
Since its inception, EIS has prioritized hands-on training in which officers, over their two-year journey, work alongside subject matter experts from CDC, state, local, tribal, and territorial health departments to lead investigations of diseases and outbreaks. In some cases, the health threat is unknown at the outset — hence the “disease detectives” nickname. The program’s logo, worn-out shoe leather, symbolizes the boots-on-the-ground work that has long characterized the hands-on training experience of the officers.
EIS has also adapted to meet the growing needs of the field of public health as evidenced by the training backgrounds of incoming classes. The first EIS class included 22 physicians and one sanitary engineer. More recent classes include doctoral-level scientists, veterinarians, pharmacists, entomologists, dentists, nurses, and other health professionals.
As epidemiologists, we are trained to ask the “Why?” and “How?” questions that uncover causes of disease, identify factors associated with hospitalization and death, assess impact on underserved communities, and ultimately control disease. Through EIS, these investigative skills are developed and honed on the job, which, over the past seven decades, have included landmark public health investigations: smallpox, HIV/AIDS, childhood lead poisoning, Ebola outbreaks, influenza pandemics, Legionnaires’ disease, toxic shock syndrome, hantavirus pulmonary syndrome, the 2001 anthrax attacks, hurricane-related health events, e-cigarette or vaping product use-associated lung injury (EVALI), the Covid-19 pandemic, the 2022 global outbreak of mpox, and many more.
In many cases, EIS officers led the investigations that described new diseases, uncovered the causative agents of an emerging condition, or stopped the outbreak.
Outside of historic disease events, public health is routinely responding to outbreaks and community health concerns that extend into our everyday lives.
In 2019, a multistate mumps outbreak investigation traced more than 60 cases to a local wedding and contained the outbreak through a measles, mumps, and rubella vaccination campaign in the affected community.
In 2022, an outbreak of gastrointestinal illness among rafters and backpackers in the Grand Canyon prompted a public health investigation where local health, state health, two EIS officers, CDC, and National Park Service colleagues collaborated to conduct interviews, environmental assessments, adapted rapid prevention messaging, and pooled sample testing of portable toilets to reveal the causative agent as norovirus.
These field investigations not only provide valuable learning experiences for EIS officers but also help control outbreaks and limit the spread of diseases. From boots-on-the-ground response to investigative analyses and study design, to partnership building and communication of key preventative measures, officers take away key skills and experiences that then shape their public health careers.
Arguably, the greatest impact of the EIS program has been filling critical public health roles both within and outside the United States with its graduates. Following completion of training, 97% continue in careers in public health while others might bring their experience to academic research or clinical practice. For state, tribal, local, and territorial health departments, EIS-trained epidemiologists serve in critical leadership roles that meet our communities where they are. Roughly 13% of recent graduates work in state, territorial, tribal, and local health positions. In 2026, 1 in 3 state epidemiologists and almost half of the current state public health veterinarians are EIS alumni.
Historically, the EIS program has also served as a pipeline for highly skilled, experienced professionals into leadership and technical roles at CDC and other federal agencies. Among three graduating classes preceding 2025, 61% work at CDC and 8% work at other federal agencies. Between 1966 and 2025, four of the 12 CDC directors were EIS alumni including William Foege, who is credited with leading efforts that ultimately eradicated smallpox.
The EIS program will celebrate its 75th anniversary this week at its annual conference in Atlanta. This is an event that typically draws more than 2,000 alumni and public health leaders in person to hear about the current work and late breaking investigations that EIS officers are leading. From cutting-edge field investigations to application of complex analytical methodologies and forward-thinking outreach techniques, this flagship offers an opportunity to share and exchange information that advances public health practice and makes our communities healthier.
The EIS conference is also where a new class of EIS officers join the ranks, meet the vast alumni network, and determine where they will be doing their training over the next two years. Beyond the training itself, EIS forges strong bonds and relationships within and between classes that contribute to a tightly knit alumni network connected by their time in EIS training. EIS conference offers a rare opportunity to bring together the alumni network in Atlanta to build on the relationships necessary for rapid communication and coordination in emergencies.
As we celebrate 75 years of training disease detectives, we reflect on the many ways in which the CDC’s EIS program has helped shape public health practice. Our partnerships are strengthened through collaboration with many public health colleagues, including laboratory leaders graduating from our sister program the Laboratory Leadership Service. EIS and its alumni network have endured the constant ebb and flow of changes across the public health system while sustaining a legacy defined by scientific discovery and safer communities. Whether the threat is an environmental exposure or communicable disease, the EIS program and its people ensure that someone is always ready to answer the call.
Eric J. Chow, M.D., M.S., M.P.H., is an alumnus of the Epidemic Intelligence Service program (2018-2020) and serves as the president-elect for the Epidemic Intelligence Service Alumni Association. Ariella Perry Dale, Ph.D., M.P.H., is an alumna of the Epidemic Intelligence Service (2020-2022) and serves as the president of the Epidemic Intelligence Service Alumni Association. Matthew Donahue, M.D., is an alumnus of the Epidemic Intelligence Service program (2019-2021) and serves as the secretary-treasurer for the Epidemic Intelligence Service Alumni Association.
