Disease Detectives

Disease Detectives

2017 Test 2017 Key 2018 Test 2018 Key


Disease Detectives is an analytical life science event that delves into the field of epidemiology - the study of the distribution and determinants of health and disease conditions in a population and ways to control them. Studying for this event will take you through the ins and outs of investigating a disease outbreak, delving into topics such as public health surveillance, different epidemiological studies, and disease transmission. Taking the test during competition will challenge your ability to analyze epidemiological data, draw significant conclusions, and translate those conclusions into viable actions to prevent and control the disease. In the end, I hope Disease Detectives introduces you to the interdisciplinary and global aspects of the public health and inspires you to become an actual disease detective, a job that will always be extremely important to our society.

How to study for the exam - Preparation

While you could just refer to the rules for a comprehensive list of topics you need to study for this event, I thought I could aid your preparation process by splitting this section into 3 parts: 1) A list of specific areas and topics that I believe are important but often overlooked, 2) General study strategies, and 3) Cheat sheet organization strategies.

1) A list of specific areas and topics that I believe are important but often overlooked: this is not an all-encompassing list, this is purely compiled from my experiences in taking many, many Disease tests, so feel free to take what you want from my advice.

  • Statistics - chi square, t test, z intervals, p values, etc. I feel this is the most overlooked topic in this event. I would recommend knowing at least basic statistical methods, since that's the main way you are going to determine if your data is significant. While most tests probably won't have you perform an actual statistical test on your data, the hardest ones will and you can easily get those extra points if you know your statistics!
  • Diseases - It's surprising that in an event called DISEASE detectives that many people forget that knowing information on actual diseases is a huge part of investigating an outbreak. Have a good understanding of various diseases and how they work, including its pathogen, life cycle, path of transmission, symptoms, and treatments. While it's not necessary to remember all the diseases known to man, I would focus on the big and prominent ones (ex. Malaria, HIV/AIDS, E. coli, ebola, etc.). While this knowledge may not be tested directly, you need a good understanding of the disease to handle an outbreak of it; how to tackle an outbreak of salmonella is very different than a Legionnaires outbreak. I would also highly suggest dedicating a section of your cheat sheet to a list of as many different diseases you can fit in with basic info about them, especially random diseases that you would never remember about but could pop up on a test (it has saved me and my partners MANY times).
  • Steps of outbreak investigation - The point I want to make on this topic is to REALLY know the steps. Most people just memorize the steps or put it on their cheat sheet, but to do well on a test you really need to understand the importance of each step and how it applies to a real investigation.
  • Surveillance - Before, this topic was largely ignored on the event, but looking at the rules this year, it seems like it's going to be more emphasized. And rightly so because surveillance is literally how epidemiologists stay updated with the world, so make sure you know more than just the definition; understand the mechanisms and its role in public health.
  • Study designs - This can often be a HUGE portion of the test, and its also high stakes because if you chose the wrong study design for your outbreak, all your calculations and analysis afterwards will also be wrong. Make sure you understand the fundamental differences between study types, what situations they're used in, the pros/cons of each, what kind of data they generate, and what conclusions they can be used to draw.
  • Calculated data - Rates, ratios, and proportions may all seem like the same thing to you right now, but in epidemiology, they are fundamentally different in nature. Most epidemiological data is going to be in the form of a rate/proportion/ratio, so know all the different types and understand when and what they are used for.
  • Control and Prevention - Some say this is the most crucial part of the investigation, and I completely agree. It's easy to remember a few generic prevention methods (*cough* education *cough*) and write those on every single test, but the responses that will score the most points include prevention methods that show you understand the nature of the disease, its impact on the population, and how best to control it. Remember to be as specific as possible and keep in mind the specific population you are targeting with these prevention methods.
  • As an ending point, I would like to remind you the importance of understanding what epidemiology is as a field of study. A lot of people can overlook this because they get caught up in all the vocab and details, but at the end of the day, to be a good Disease Detective, you need to know that epidemiology is a study of populations and why that is useful.

2) General study strategies: Even after knowing what information you need to acquire, creating a plan of attack can often be overwhelming and seem impossible. But it is possible! Below are some suggestions on some general methods of studying.

  • If you are a newbie to this event, start with vocab lists!! It's hard to understand deeper topics if you don't know what the difference between a epidemic and a outbreak is (trick question: there's not really a difference. According to the CDC, it's purely a matter of how severe public health officials want the population to see the issue).
  • Look at case studies , whether on previous tests or on CDC reports. Case studies often have every single step of outbreak investigation recorded, including what the public health officials did and why the did it written in a manner that can connect each piece by logic that you couldn't have seen by just studying each part.
  • PRACTICE TESTS. AND MORE PRACTICE TESTS. They'll expose you to questions and problems that you may have never seen before, which you will now have in your tool kit for the real competition!
  • Keep up to date on recent outbreaks! Many people forget that there are real outbreaks happening around us constantly. A huge outbreak that happened last year will most likely show up on your tests (ex. ebola), so make sure you are staying updated.

3) Cheat sheet organization strategies:

  • I really only have one piece of advice on this topic - focus on only including straight definitions and facts, but don't crowd the sheet with deeper understandings and connections that you should know by heart. Ex: you can list the different types of errors/biases and their definitions on the sheet, but you don't need to include specific examples of those errors in a study because you should have a good enough understanding of the errors that you can figure out the type of error in any example.

What to expect during the test - During the competition

Competition day can be stressful. But technically, this should be the easy part: you've already learned all the information, now you just have to apply it. Here are a couple of pieces of advice for the big day:

  1. The first thing you should do during any test is quickly analyze how long the test looks. This will help you better pace yourself. Keep in mind: just because the questions are multiple choice doesn't mean it won't take a lot of time!
  2. Always split the test with your partner. If the test is short and you have extra time, check through each other's problems, but initially splitting the test usually is the most efficient use of time. For Disease Detectives specifically, never split a single case study between partners, unless absolutely necessary. Everything in a case study is connected and having one person know everything will be easier and way more useful.
  3. Don't freak out if the question isn't in a format you're familiar with or doesn't directly ask you what you learn - ANALYZE, DON'T REGURGITATE. Apply your knowledge and understanding to the question, and worst comes to worst you can get partial credit :)

Some helpful resources


  • Principles of Epidemiology - official textbook by the CDC and free to download online (it's the first link that pops up if you Google it). Not everything in the textbook is necessarily relevant and important, but it's not a difficult read and will give you a good background and understanding of what epidemiology is. CDC is sponsoring the event after all!
  • Basic Epidemiology - official textbook by the WHO and also free to download online. Personally I would say the CDC textbook covers the topics more succinctly, but it doesn't hurt to have another source of information.

Other resources:

  • Here is a statistics sheet that was on soinc.org a couple of years ago, I found it super useful as a brief summary of the different tests that you would need to know
  • Here is a CDC glossary of epidemiologic vocabulary terms - great place to start out if you don't know anything of public health!
  • CDC Morbidity and Mortality Weekly Reports (MMWR) - these are official report that the CDC posts on their website every week on outbreaks and studies that going on right now. They are super helpful for identifying outbreaks that are relevant now, and there's even an app you can download on your phone. You can read it like the news :)

About the author

Evelyn Zhang is an undergraduate at Stanford University, majoring in Human Biology. She is a national champion in Disease Detectives.

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