GENERAL: This lab continues computer based explorations of statistical prediction of epidemics, a tool used by epidemiologists. This week’s exercise will be carried out using computer software called STELLA. The program is a pre-configured model system that allows students to identify fitted parameters to a published data set for an epidemic in a boarding school. The probability of disease transmission in this dynamic model is less than 100%, therefore the percolation model used in the previous activity is not valid in this study.

OBJECTIVES: In the previous exercise, you used a computer model to explore a limited epidemic. In this week’s scenario, you will be introduced to a dynamic system, that includes estimating the number of person-to-person contacts and calculating the expected number of new infections each day. The influence of additional variables (e.g., time delay from exposure to onset of the symptoms; natural or vaccine-induced immunity; quarantine) will be studied to understand how they influence the computer model.

INTRODUCTION: In this exercise, you will focus on a case where disease transfer is influenced by several variables within a population, thus creating a dynamic system. The scenario: One student enrolled in a boarding school catches an infection from a sibling during a visit home. The student returns to school, moves around among fellow students, thus interacting with an ever-changing subset of other students, exposing them to the infection. Some of his fellow students become infected; others do not.

EQUIPMENT AND PROCEDURE:

Further instructions and follow-up activities will be given to you at the time of the lab by Dr. Selinger and her assistants.

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