This model reveals the differences between the daily cases and daily new cases. It also allows students to label an individual person in the population, examine the chance at which the person is infected, and follow the person through the epidemic.
Grades: 9-12;
The model starts with a human population consisting of susceptible (green color)people. Once a carrier (orange color) appears in the population, it will pass the disease to one of the susceptible people nearby (within a radius of 1.5) at the defined transmission rate. The carrier may become sick (infectious red color) after the defined incubation period. The sick people will be isolated, so they do not infect others. The sick people will remain ill for 14 days. By the 15th day of being sick, they die (disappear from the model) at the defined mortality or recover and become immune to the disease (blue color).
Buttons, Sliders, and Switches:
The population size slider is self-explanatory. So are the buttons of Set up/Reset, Run/Pause, and Run a day.
The Vaccination-rate slider and vaccination button determine the vaccination coverage of the population.
The Transmission-rate slider determines how likely a susceptible person is infected when exposed to the disease.
The Mortality slider determines how likely the infected people die on the 15th day.
The Incubation-period defines the number of days between a person is infected and becomes sick.
The Illness-period defines the number of days between a person becomes to show symptoms to recover.
The +1 Carrier button adds a carrier into the population.
The Select to watch a person button allows you to focus on an individual person. You may compare how often the person gets infected in different situations.
The Stop watching button allows you to stop watching the person.
First, choose the factors, such as population size, transmission rate, etc.
Click on "Set up/Reset" then "Run/Pause." The model is set to stop when there are no infectious people.
Observe the infection changes in the population in the plot and monitor.
Use "Run one day" to run the model in a controlled way and collect day-by-day data.
THINGS TO TRY
There are so many things you can try in this model. Here are only very a few quick ideas:
How does the number of daily cases differ from the number of daily new cases?
How does the change in the number of daily cases related to the change in the number of daily new cases?
How can the daily cases and/or daily new cases be used to measure the severity of an epidemic? Why?
Dr. Lin Xiang creates this model at the University of Kentucky. If you mention this model in a publication, we ask that you include the citations below.
Xiang, L. (2021). Infectious Disease Outbreak-daily cases and daily new cases. Department of STEM Education, University of Kentucky, Lexington, KY.
Questions? Comments? Email us.