Eric Willhelm
Jerrick Morsey
Teacher
The program
Steps to run program:
Blue,white and yellow dots belong to one of the groups.Green is normal and red is sick and cyan (light blue) go to the attractors.
Introduction
Our project is the simulation of the spread of a disease within a community. In recent years, the spread of infectious diseases has become a major fear due to new diseases, such as the SARS epidemic. Therefore, the intent of our simulation is to provide information regarding how to deal with such diseases.
Since many diseases that people fear spread through the air, we chose to model droplet transmission with our simulation. Transmission by droplet contact involves droplets from an infected person’s cough or sneeze contacting surfaces of another person’s nose or mouth; these droplets quickly settle out of the air. These droplets are generally greater than 5 microns in size and usually move up to 3 feet before settling. This method of transmission is the method that is used by the pathogen that causes SARS.
Our program uses stochastic modeling to simulate droplet transmission of a disease among a population of individuals within a town. The program moves people within the community and organizes them into various groups while the disease progresses. It allows the modification of several parameters to quantify those parameters’ effect on the rate of disease spread. Some of these parameters are population size, number of groups, size of groups, and length of contagiousness
Project Description
The program was initially intended to determine the point at which an airborne disease would reach epidemic levels. However, the definition of “epidemic” used by the CDC (an unusual spike in the number of cases of a given disease in a given region) told us that we were already modeling an epidemic, regardless of its behavior. Therefore, the focus of the project shifted to the determination of methods to help control such an epidemic on a municipal scale. Another problem was the nature of “airborne transmission”; a disease that uses airborne transmission can be carried in the air for long distances. However, SARS, the disease whose dangers inspired this program, does not use airborne transmission. It uses “droplet-contact transmission”, in which the disease is carried in droplets briefly suspended in the air from an infected person’s cough or sneeze. Our simulation has therefore been created to determine how to control a SARS-like epidemic by altering various parameters withi! n our simulation to determine those parameters’ effect on the percentage of infected people within a community.
The simulation was designed to represent a community. As in a real community, numerous people move about randomly. Although in reality people move in ordered and purposeful ways, the combined movements of all people can seem random when taken as a whole.
People do not move with complete randomness, however. In reality, people congregate in various ways. We assume that people congregate in two basic ways: the “boxed group” and the “attractor”. The boxed group involves a group of people that periodically meet within a given area separate from the general public. This would be similar to a school, church, stadium, or theater, since sets of people generally come and go in unison at specific times. The attractor involves a set location where individual people come and go, but there is generally a group of people open to the public. The attractor would be similar to a store, airport, or office, where there are constantly people but not the same set of people.
Recommendations
In order to gain more insight into the problem of disease spread with our simulation, we could run more sets of simulations.
Given more time, we could run more simulations. We could explore the behavior of diseases that require different amounts of time to remain contagious, and we could examine the disease’s behavior among communities with populations of different sizes. We could also alter multiple parameters to determine better solutions to the problem of disease spread.
We could also alter the simulation itself. A major problem that we could never solve was how to deal with differences in gender, age, and race with regard to susceptibility to disease; we simply treated all people the same within the simulation. Another problem was that we could never deal with “fomites”, or inanimate objects, such as tables or chairs, that become briefly contaminated when infected droplets from a person’s cough or sneeze land on them after they settle out of the air; they are capable of carrying a droplet-transmitted disease. [3] However, we were not able to deal with any of these problems due to time constraints.
References
[1] Part II. Recommendations for Isolation Precautions in Hospitals
[4]Methods of Disease Transmission
[5]What is SARS (Severe Acute Respiratory Syndrome)
[6]Outbreaks vs. Epidemics – Whether it’s time to freak about the flu.