Inspiration for the model: The Last of Us, a video game for PlayStation 4.
In this example, we used a system dynamics model to predict a spread of a dangerous infection called Cordyceps Brain Infection, which is immune to any type of antibiotics. In the beginning, the virus was carried by only one person (Infected), which inhaled spores from a plant called cordyceps fungus.
The Infected show their first symptoms after two days, as the infection attacks higher brain functions, making the infected highly aggressive and incapable of reason or rational thoughts.
The infection can be transmitted via bodily fluids; such as saliva, or by inhaling spores from the afore mentioned plant.
It is believed that the infection can last up to 10 years, before the host dies.
Parameters such as Infectivity, Contact Rate and Immunization Rate can be adjusted, but as we are dealing with a highly infectious disease, the starting values are 0.97 (infectivity - in 97% of the cases, the infection will spread to another host); 5 (each infected attacks 5 susceptible person per day); and 0.0001 (only 1 infected per 10,000 infected gets the treatment, as the vaccine can be afforded only by the richest people on the Earth).
Simulation time is set to 50 years. The purpose of this model is to simulate what kind of an effect a deadly infection would have on World's population, if the medicine could not find a cure, or if the cure would be available only for the richest people on the Earth.
The simulation result shows that the Earth's population has been decimated with the disease, and that there are only 7,5 million people left on Earth.