Education Outreach

Abstract

BioTechniquesVol. 47, No. 3 Education OutreachOpen AccessEducation OutreachDawn AldermanDawn AldermanAffymetrix Corporation, Branford, CT, USASearch for more papers by this authorPublished Online:25 Apr 2018https://doi.org/10.2144/000113239AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInReddit Communicability of Infectious DiseasesThis month we focus on a simulation exercise designed to teach people how easy it is to spread communicable diseases. Whether it is the influenza virus, H1N1, or AIDS, this simulation will demonstrate how multiple encounters with an infected person can lead to the spread of disease. The aim is to help young children understand the importance of hand washing and good personal hygiene.The exercise is appropriate for kindergarten through undergraduate students and is adaptable to large- or small-sized classes (1). It is important to set up the experiment for a predetermined class size, because you must prepare one cup of liquid for each student participating in the exercise. Each student will be supplied with an “exchange” cup containing a liquid, except for one student who will start the exercise with an “infected liquid” exchange cup. During preparation, fill all exchange cups halfway with water, except for the infected liquid exchange cup, which is filled halfway with either an acidic solution (if using phenolphthalein as the indicator reagent) or a starch solution (if using iodine). There should be no indication (labeling, color, etc.) of which cup has the infected solution.Disease exchangeThe unidentified liquid in the cups represents the bodily fluids that may be exchanged either through poor hygiene or by sexual encounters. Each student randomly chooses a partner to exchange his or her liquid with. The exchange is a mixing of the two partners' liquids. Each student should make a total of six exchanges (never exchanging with the same person twice). After each exchange, he or she should place a small sample from his or her cup into a clean sample cup. When all of the exchanges are complete, the student should add a drop of the appropriate indicator solution (phenolphthalein or iodine) to the seven sample cups (be sure to have a water control) to identify if he or she has been infectedThe class can then collect and graph the data. The results will be as follows: for a large class after 2 exchanges, 4 people will be infected, after 4 exchanges 16 people will be infected, and after 6 exchanges 64 people will be infected (assuming each infected student only exchanges each time with an uninfected student). Note that data will vary from class to class.The students are generally in awe at how quickly the communicable diseases spread. The educator can take this opportunity to explain to the students that this is a simulation and that in real life disease would not spread so rapidly. The educator can then ask the students to consider why the diseases would not transmit at such a rapid rate.Note that there is no way to identify the initially infected individual after the exchanges are complete. In order to find out who the originally infected person is, have each student take a sample before the exchanges begin. A small class setting would require a reduction in exchanges to eliminate the entire class being infected.VaccinationsTo demonstrate the effects of vaccination, the simulation can be repeated with one student having a cup marked “vaccinated” or “vaccine”. This cup should contain only water. The student should participate in the exercise, but should not actually exchange liquid. Although there is no actual mixing of the liquids, the exchange between the vaccinated student and the non-vaccinated student counts as an exchange for both. The addition of a vaccinated student will demonstrate the effectiveness of a vaccination against a virus and allow for the educator to segue into discussions about vaccines and how they are created and used.The supplies for this exercise can be found at the local store (starch/iodine). The exercise can also be introduced as a higher level study by using chemical reagents (acid/phenolphthalein). Best results are achieved if all exchanges are complete before adding the indicator reagent.AcknowledgmentsSpecial thanks to Ms. Jen Diana at the University of New Haven, CT for identifying this exercise and introducing it to us.