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Ecology of Infectious Disease: Data Mining the National Notifiable Diseases Surveillance System (NNDSS) for Ecological Patterns

Author(s): M. Caitlin Fisher-Reid

Bridgewater State University

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This is a multi-day, small-group, jigsaw assignment that uses publicly available data from the CDC's National Notifiable Diseases Surveillance System (NNDSS; to detect ecological patterns of human infectious disease. I use this module in a junior/senior level evolutionary medicine course to help students connect ecological concepts (e.g., population density, environmental transmission pathways) to human infectious disease. I have deliberately selected five diseases which show strong, weak, or no seasonal patterns in infection case rate. I provide students with 5 years of data for each disease, at the national level and for 6 states with a similar magnitude of human population size, but different magnitudes of population density and from different climate regions, including the state the majority of my students are from, Massachusetts.

Over four 75-minute class periods, students work in small groups to first learn about their disease and explore their data, and then compare the five diseases in new jigsaw groups. The first day is spent introducing the module and having students work together to learn about their disease. I provide guiding questions to help them focus on the relevant information on the internet. At the end of the first day, and into the second day, the groups produce graphs which demonstrate presence/absence of ecological patterns. By the end of the third day, each group writes a brief report interpreting these results in context of what they learned about their disease. This is submitted to me for assessment using the attached rubric, and is shared among original disease group members during the jigsaw day. The final day is the jigsaw day. I reshuffle the student groups so that every new group has at least one member representing each of the five diseases. The representatives share their original group's findings using the report, and spend the class trying to determine if there are any commonalities or take-home messages they could give a concerned community member about the ecology of human infectious disease.

Throughout the four day period, I circulate among the groups, serving as a sounding board for their analysis and graphing ideas. I specifically tell them that they should only work on this assignment during these four class periods (they have separate writing assignments that I want them to focus on at home). I have run this exercise successfully in both the virtual (Zoom with breakout groups) and in-person classroom. Each year, I update the spreadsheets to include the most recent five years of data so that the students are focusing on the most recent data. I have a 20-student class, so the original disease groups are groups of 4 students, and the jigsaw groups are groups of 5 students. Depending on class size and goals of the instructor, additional diseases/focal states/years could be added to this assignment relatively easily by downloading the relevant data from the NNDSS.

The following documents are attached in a Zip folder, and when teaching, I post all of these files to our LMS for students to access during class (except for the Excel spreadsheet, Instructor_Diseases_Plotted.xlsx):

  • NNDSS Assignment 2021.docx: guidelines for first three class periods
  • NNDSS Introduction.pptx: first class intro slides (~5 min)
  • NNDSS Jigsaw.docx: guidelines for jigsaw day (fourth and final class period)
  • NNDSS Report Rubric 2021.docx: grading rubric for the disease report produced by the original groups by the end of Day 3.
  • Data: Five compiled Excel spreadsheets of national and state case data for five diseases over five years (2016-2020). One file per disease, with seven sheets of data organized by country and state.
    • Diseases included: chlamydia, cryptosporidiosis, gonorrhea, pertussis, sallmonellosis.
    • States included: AZ, MD, MA, MO, SC, WA.
    • Additional diseases and states can be accessed at NNDSS site.
  • Instructor_Diseases_Plotted.xlsx: Instructor file of plotted national data for each of the five focal diseases showing weekly case rates for each of the five years. I use this file to get a feel for the patterns for each disease ahead of time so that I can give the students hints while they work if they are not sure how to proceed.

This assignment was inspired by a similar one using the NNDSS data for figure making and data exploration developed by Sheila Schreiner at Salem State University and presented at the June 2017 Project Kaleidescope (PKAL) Massachusetts Regional meeting.


Data from 2016-2020. More recent data can be downloaded from NNDSS at

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