Extracurricular activities have the potential to introduce young persons to EPHS careers [4,8–11]. The National Science Olympiad (NSO; www.soinc.org) is an extracurricular program dedicated to improving the quality of K-12 science education, increasing interest in science, creating a technologically literate workforce, and providing recognition for outstanding achievement by both students and teachers [9,11,12]. NSO includes a series of regional, state, and national tournaments involving 23 separate science or engineering events. The Disease Detectives event has been a part of the competition since 2000. CDC has provided training and resources for coaches and regional and state event developers, and works with NSO to update rules and content. CDC staff develop events for national tournaments and host first-place high school teams on a tour of its Atlanta, Georgia, headquarters. The majority of the work is provided by the thousands of teacher and parent coaches, event supervisors, and state directors who train, plan, organize, conduct, and manage the program.

The Disease Detectives event started as a high school level competition with a focus on applied epidemiology. Concepts included in The Principles of Epidemiology in Public Health Practice, third Edition [13] represent a substantial amount of the subject matter. NSO Disease Detectives competitions include a written exam and follow a scenario-based, case-study format with objective questions and detailed scoring rubrics. Students compete in teams of two and are encouraged to collaborate and consult with their teammates during competition.

The high school student success with the NSODD event led CDC to sponsor introduction of the event into middle school competition in 2006. The intent was to expose students to the fundamental principles and concepts of EPHS for seven years (three years in middle school and four years in high school) and include more complex and sophisticated principles in the high school competitions (Table 2). In 2012 for example, experimental error, including the concepts of bias and confounding, was introduced into high school competitions, and in 2014 basic descriptive and analytic statistics became part of the competition. Plans are to make NSODD more interactive, possibly by adding a component where teams would propose projects to address specific public health problems before the tournament. During 2015e2016, approximately 7500 middle and high schools competed in NSODD. Because each NSODD team included at least two students, approximately 15,000 middle and high school students were exposed to EPHS.

Our experience demonstrates that, when presented in the proper context, middle and high school students can master the material presented in the majority of introductory epidemiology courses. NSO has demonstrated success in bringing students into public health careers. For the first time, in 2016, the first candidate known to have participated in NSODD as a high school student was accepted into CDC’s Epidemic Intelligence Service (EIS) program, a 2-year, post-doctoral program in applied epidemiology (https://www.cdc.gov/EIS/).

Medical and veterinary students have potential to become or work with public health professionals but might not have been exposed to applied EPHS activities during their training. Established in 1975, the CDC EEP provides training for medical and veterinary students in EPHS through applied epidemiology service learning. The EEP also introduces medical and veterinary students to EIS and careers in public health [14].

During their EEP rotation, students engage in applied epidemiology through projects that may include working with surveillance systems, collection and analysis of data, developing guidelines for public health problems, or conducting literature reviews and metaanalyses. If feasible, EEP participants are also deployed with EIS officers to the field for outbreak investigations [15–17]. During the 6- to 8- week rotation at CDC, EEP participants attend CDC seminars, including weekly epidemiology grand rounds presentations given by EIS officers that are based on field investigations or analytic studies (i.e., Tuesday Morning Seminar).

EEP is an effective means to generate interest inpublic health and CDC. From June 1975 through May 2016, 1795 students joined the EEP. Of these, 221 (12.3%) became EIS officers by July 2016, with 17 in EIS training. Of 204 EEP alumni who graduated EIS by July 2016,134 (65.7%) were employed in public health as their first job after EIS.

EEP provides real-world experience in public health and applied epidemiology through service learning and agency seminars. Hands-on activities give EEP participants an understanding of the work of CDC public health professionals. Examples of projects conducted by recent EEP participants include data analysis on the clinical presentation of botulism, developing a risk assessment tool for a study on rabies in Haitian dogs, a qualitative analysis of cancer-control plans and analysis of Brucella canis exposure data from diagnostic labs across the United States. Field deployments enable participants to work with EIS officers during outbreak responses, see first-hand how CDC works with partners, and practice their clinical skills in a public health setting. Seminar attendance allows participants to gain the perspective needed to work at the intersection of clinical medicine and public health.

EEP engages students early during their training to prepare them for future careers, whether they choose to work in clinical or public health settings. Students are better able to work collaboratively across disciplines and gain an introduction to the work of public health practitioners, develop a better understanding of prevention, and gain first-hand knowledge of public health systems and approaches used. EEP participants learn about population health and are better positioned to actively participate in and lead the health system.