Disease detectives science olympiad is one of the more misunderstood events on the roster, since most students assume it's a general biology or health event until they sit down with a released test and realize it's closer to a statistics exam wearing a public health costume. Run in partnership with the CDC, the event tests real epidemiological reasoning: reading outbreak data, calculating rates, and evaluating whether a suspected cause actually holds up. This guide covers the event's three-part format, the core concepts you actually need to know, and how to study for it using the same materials the CDC built for exactly this purpose.
What Disease Detectives Actually Tests
According to Science Olympiad's own event page, Disease Detectives has participants "use their investigative skills in the scientific study of disease, injury, health, and disability in populations or groups of people." It's built in direct partnership with the CDC, which is part of why the event tests real epidemiology rather than general science trivia.
The event splits into three roughly equal parts:
| Part | Focus | What You're Doing |
|---|---|---|
| 1. Background and Surveillance | Foundational epidemiology concepts | Defining terms, understanding how disease is tracked |
| 2. Outbreak Investigation | Applying concepts to a scenario | Reading data, calculating rates, identifying the likely source |
| 3. Patterns, Control, and Prevention | Response and prevention reasoning | Explaining how an outbreak should be contained going forward |
A disease detectives science olympiad team that treats this as a memorization event usually underperforms. The test rewards students who can apply the same handful of concepts to a scenario they've never seen before, not students who memorized last year's answer key.
The Three-Part Event Format
Part 1 sets up the vocabulary and framework you'll use for the rest of the test: the agent-host-environment triad (what's causing the disease, who's susceptible, and what conditions let it spread) and the chain of transmission. Part 2 hands you a scenario, real or realistic outbreak data, and asks you to work through it: interpreting epi curves, line listings, and cluster maps to figure out what's actually happening. Part 3 shifts from diagnosis to response, asking what public health steps would actually control or prevent the outbreak you just investigated.
Divisions and Team Structure
Disease Detectives runs in both Division B (grades 6 through 9) and Division C (grades 9 through 12). The core concepts overlap heavily across both divisions, but Division C pushes further into statistical calculation and expects faster, more independent reasoning through complex data. A team moving from Division B to Division C should expect the same event skeleton with real jumps in both speed and depth.
Core Epidemiology Concepts You Need to Know
A handful of concepts show up across nearly every Disease Detectives test, and knowing them cold matters more than broad outside reading.
Attack rate, relative risk, and odds ratio. All three measure some version of "how much more likely is a person to get sick," but they're calculated differently and answer slightly different questions. Confusing them is one of the most common ways students lose points on calculation questions.
The Bradford Hill Criteria. A set of considerations, strength of association, consistency, temporality, and several others, used to evaluate whether a suspected cause of an outbreak is actually likely to be the real cause, rather than a coincidence. This shows up constantly in Part 3 reasoning.
PFGE gels, SNP mapping, and the PulseNet concept. Laboratory techniques used to determine whether cases across different locations are actually the same outbreak strain, a real tool epidemiologists use and one the test expects you to recognize and interpret.
Reading an Epi Curve
An epi curve graphs the number of new cases against time during an outbreak, and its shape is the whole point. A curve with one sharp spike suggests a single point-source exposure, everyone got sick from the same source around the same time. A curve with a slower climb and a longer tail suggests person-to-person spread, where each new case creates the possibility of more. Learning to read that shape quickly, rather than working it out from scratch each time, is one of the highest-value study habits for this event.
How to Study for Disease Detectives
Science Olympiad's own event page hosts released invitational tournament tests going back several years, a glossary of epidemiologic terms, and recorded webinars on outbreak investigation. Working through actual released tests, not generic epidemiology review material, is the single most direct way to prepare, since the test's specific question style is consistent year over year even as the scenarios change.
The CDC's NERD Academy is a second real resource worth using directly: an eight-module curriculum built for grades 6 through 12 that walks through exactly the concepts this event tests, what counts as an outbreak versus an epidemic, how public health data gets collected and visualized, and how contact tracing actually works. It's built by the same agency that partners on the event, which makes it a closer match to what the test expects than a generic biology textbook chapter on infectious disease.
Common Mistakes Teams Make
Studying general biology instead of the specific concepts tested. Disease Detectives isn't a general health or biology event. Time spent reviewing broad disease facts is time not spent on epi curves, rate calculations, and the Bradford Hill Criteria, which is what actually shows up on the test.
Mixing up attack rate, relative risk, and odds ratio. These three get confused constantly because they're conceptually related. Practice each one with real numbers until the difference is automatic, not something you have to reason through mid-test.
Skipping the released practice tests. Generic epidemiology quizzes online don't match this event's specific question style. The actual released invitational tests on soinc.org are a far more accurate practice tool than anything written for a general audience.
Treating Part 3 as an afterthought. Prevention and control reasoning is a full third of the test, and it's the part students most often run out of time for after spending too long on Part 2's calculations.
Frequently Asked Questions
What is Disease Detectives in Science Olympiad?
A Science Olympiad event, run in partnership with the CDC, where teams apply epidemiology skills to investigate disease outbreaks. Students interpret outbreak data, calculate rates, and reason through prevention and control questions across a three-part test.
What divisions is Disease Detectives offered in?
Both Division B (grades 6–9) and Division C (grades 9–12), with the same core epidemiology skills tested at both levels, though Division C questions typically go deeper into statistical calculation.
What topics does Disease Detectives cover?
Reading epi curves and line listings, understanding the agent-host-environment triad and chain of transmission, calculating rates like attack rate, relative risk, and odds ratio, and applying the Bradford Hill Criteria to evaluate whether a suspected cause of an outbreak actually holds up.
Do I need a science background to compete in Disease Detectives?
No formal epidemiology background is required going in, but the event rewards students comfortable with statistics and data interpretation. Most competitive teams study specifically for it using Science Olympiad's own released practice materials.
What's the difference between Division B and Division C Disease Detectives?
The core topics overlap heavily, but Division C tests more advanced statistical reasoning and expects faster, more independent interpretation of complex outbreak data. Division B introduces the same concepts at a level appropriate for younger students.
What is an epi curve?
A graph showing the number of new cases of a disease over time during an outbreak. Its shape tells you how the outbreak likely spread, a single point-source exposure looks different from an outbreak that kept spreading person to person.
How is Disease Detectives scored?
Through a mix of graph and chart interpretation, written explanations, calculations, and closed-ended questions across the event's three parts. Exact scoring weights are set in each year's official rules manual, published by Science Olympiad.
Where can I find official practice materials for Disease Detectives?
Science Olympiad's own event page hosts released invitational tournament tests, a glossary of epidemiologic terms, and webinar recordings. The CDC's NERD Academy curriculum also covers the underlying epidemiology concepts in a format built for grades 6 through 12.
The Bottom Line
Disease Detectives rewards the same habit that makes a strong independent research project work: understanding a small set of real concepts well enough to apply them to something you haven't seen before, instead of memorizing answers to questions you have. Students who put in the reps with actual released tests and the CDC's own curriculum consistently outperform students who reviewed general biology and hoped it would transfer. That same skill, reading real data and reasoning carefully about cause and effect, is exactly what a first independent research project asks of you.
If Disease Detectives sparks a real interest in epidemiology or public health, that's worth turning into an actual project rather than letting it end when the competition season does. Our guide to starting a research project in high school walks through exactly how, and the Aspire Research Fellowship pairs you with a PhD mentor and a recent ISEF champion over 12 weeks to do it, open to grades 8 through 11, with more than 20,000 students through the program so far.
Apply to the Aspire Research Fellowship →
For the full picture of how Science Olympiad works beyond this one event, see our guide to what Science Olympiad actually is, or explore research topics for high school students if this event has you thinking about a project of your own.