Infectious Disease Outbreak-daily cases and daily new cases
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WHAT IS IT?
This model simulates the epidemic dynamics in a human population based on a revised SEIR model, i.e., in this model the infectious (I) are fully isolated at home or in hospitals so that they do not transmit the disease. This model reveals the differences between the daily cases and daily new cases. Besides, this model allows students to label an individual person in the population and examine the chance at which the person is infected and follow the person through the epidemic.
HOW IT WORKS
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 determines 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.
HOW TO USE IT
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?
RELATED MODELS
Find this model series at http://3dsciencemodeling.com
- Infectious Disease Outbreak-Basic Phenomenon
- Infectious Disease Outbreak-Transmission and mortality
- Infectious Disease Outbreak-Population Comparison
- Infectious Disease Outbreak-HealthCare, Isolation and Quarantine
- Infectious Disease Outbreak-Social distancing
- Infectious Disease Outbreak-Vaccination
- Infectious Disease Outbreak-SEIR model
CREDITS AND REFERENCES
Dr. Lin Xiang (lin.xiang@uky.edu) created this model at the University of Kentucky in 2021. 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.
This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/4.0/.
Comments and Questions
;; ;; This model is developed by Dr. Lin Xiang at the University of Kentucky. Contact: lin.xiang@uky.edu ;; ;; If you see this page rather than a "download" button when downloading the model, click the "download" icon ;; in your browser to download this model file. ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; turtles-own [ days-after-exposure days-of-sick labeled] Patches-own [ ] Globals [ watching max-daily-cases daily-new-cases max-daily-new-cases] to setup ca setup-turtles set watching false reset-ticks end to setup-turtles create-turtles population-size [set color 68 set size 1.25 set labeled 0 set shape "person" setxy random-xcor random-ycor ] end to go if ticks > incubation-period and count turtles with [color = red] = 0 [stop] set daily-new-cases 0 move transmission incubation sickness find-max-daily-cases tick end to move ask turtles with [shape = "person"] [right random 360 forward mobility] end to add-a-carrier ask one-of turtles ;choose a random person [set color orange ;set the color as orange (carrier color) ] end to transmission ask turtles with [color = orange] ;Hi, carriers [let susceptible-person one-of other turtles in-radius 1.5 with [color = 68] ;Are there any susceptible people near you (within a radius of 1.5)? if susceptible-person != nobody ;If there is at least one [ask susceptible-person ;ask the suscetiple person [ if random 100 < transmission-rate ;at the defined transmission rate [set color orange] ;to become a carrier (orange color) ] ] ] end to incubation ask turtles with [color = orange] ;Hi carriers [ifelse days-after-exposure < incubation-period ;If the number of days after you get infected is smaller than the defined incubation period [set days-after-exposure days-after-exposure + 1] ;increase the number of days after exposure by 1 [set color red set shape "house" ;otherwise, become infectious (red color) set daily-new-cases daily-new-cases + 1 ;count daily neew cases if daily-new-cases > max-daily-new-cases ;find the max daily new cases [set max-daily-new-cases daily-new-cases] ] ] end to sickness ask turtles with [color = red] ;Hi sick people, [ifelse days-of-sick <= illness-period ;if you have not been sick for 15 days [set days-of-sick days-of-sick + 1] ;remain sick and increase the number of sick days by 1 [ifelse random 100 < mortality ;otherwise, at the define mortality rate [die] ;die [set color blue set shape "person"] ;or recover ] ] end to vaccination let num-of-susceptible (count turtles with [color = 68]) ;find the number of susceptible people let num-of-vaccinated (num-of-susceptible * vaccination-rate * 0.01) ;calculate number of susceptubel people to be vaccinated ask n-of num-of-vaccinated turtles with [color = 68] ;find these many susceptible people [set color blue] ;set as immune (blue) end to find-max-daily-cases if count turtles with [color = red ] > max-daily-cases ;Count the infectious.If it is greater than the current record of max daily cases [set max-daily-cases count turtles with [color = red ]] ;update the max daily case end to watch-an-infected-person watch one-of turtles with [color = red] end to label-a-person if any? turtles = false [user-message "Nobody is here." stop] if mouse-inside? [ if mouse-down? [ let labeled-person min-one-of turtles [distancexy mouse-xcor mouse-ycor] if labeled-person != nobody [ ask labeled-person [set label "me" set labeled 1] ;label the 1st selected person as me watch labeled-person] ]] if count turtles with [labeled = 1] >= 1 [stop] ;disable the button when one person is labelled. end to unselect ask turtles [set labeled 0 set label ""] rp end
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