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JOURNAL OF MICROBIOLOGY & BIOLOGY EDUCATION, December 2015, p. 278-279 DOI: http://dx.doi.org/10.1128/jmbe.v16i2.919
A Simulation of Communicable Disease and Herd Immunity for the Microbiology Classroom or Laboratory Jeff Wiles Department of Natural Sciences, Middle Georgia State University, Macon, GA 31206
INTRODUCTION Although it is reasonably easy and safe to use live organisms in the microbiology laboratory, communicable diseases caused by the transmission of infectious microbes is an important topic that cannot be directly viewed in a laboratory environment. Direct contact transmission exercises (4) using fluorescent dyes such as Glogerm (www. glogerm.com) are useful in teaching the ease of transfer from person to person and the efficacy of proper hand washing. Other simulations use pen and paper to track who has been infected through handshakes during a period when the students are instructed to shake one another’s hands (1, 6). Liquid transfer exercises (7) model sexually transmissible diseases and stress the invisible nature of the infectious agent. None of these model how infections spread in real time from person to person as a consequence of the normal activities they undertake each day. Using a set of cards as proxies for infectious organisms allows students to see how easily and quickly a disease can spread through a susceptible population. After taking part in this exercise, the students should have a clearer understanding of how frequently they are in a situation where microorganisms can be transferred from person to person, how a single infectious individual can inadvertently cause an outbreak, and how vaccination and herd immunity block the spread of communicable diseases. This simulation was designed for use in Microbiology for the Health Sciences, but it should work equally well in high school health or biology classes, introductory college biology courses, or any microbiology course. Additionally, it can be used in a class that does not contain a laboratory portion. The course for which the exercise was designed has a normal enrollment of twenty-four students, but it is expected that both smaller and larger classes should be able to make good use of the simulation. The term “Game” was chosen specifically for this exercise to make it clear to both the participants and to anyone who came across a misplaced set of cards that this is Corresponding author. Mailing address: Biology Department, Middle Georgia State University, 100 University Parkway Macon, GA 31206. Phone: 478-471-2830. E-mail: [email protected].
a purely intellectual exercise and not an act of bioterrorism or other malicious event.
PROCEDURE To prepare for the exercise, a number of small cards roughly equal to the number of students in the class was made. Stiff, brightly-colored paper was used to increase durability and visibility. The small size made them easily portable and easily concealed. A single student in the class was given a large set of identical cards that listed out the rules for how to distribute them (Fig. 1). Keeping the game secret, as described in Rule One, prevented students from altering their behavior to avoid infection. It would be contrary to the goals of the course for students to stop studying in groups, exchanging notes, and helping each other in the laboratory. When the “infected” student came in contact with another student as described in Rule Two, the new student became “infected” as well. They received half of the cards possessed by the first student. Optimally, the original student passing cards on to the new student would also explain the rules. If the infecting student did not explain the game, the newly-infected student at least had the rules from the cards to rely on. Space limitations prevented the inclusion of rules of whether to round up or down when giving cards but this problem was avoided by using 2n cards at the start, where n was the smallest number required for
Welcome to The Infection Game RULE #1 Do not discuss The Infection Game with anyone. It will be a better simulation if fewer people know. RULE #2 If you talk to, touch, or sneeze/cough near one of your classmates, PRIVATELY (Rule #1!!) give them HALF of your infection cards. RULE #3 NEVER give away your last infection card; if you are already infected, DON’T take more cards from anyone. RULE #4 If you have exactly one infection card, email your instructor ASAP – [email protected] FIGURE 1. Layout and text of the infection cards.
©2015 Author(s). Published by the American Society for Microbiology. This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial-NoDerivatives 4.0 International license (https://creativecommons.org/licenses/by-nc-nd/4.0/ and https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode), which grants the public the nonexclusive right to copy, distribute, or display the published work.
278
Journal of Microbiology & Biology Education
Volume 16, Number 2
WILES: COMMUNICABLE DISEASE AND HERD IMMUNITY SIMULATION
each student to be able to end up with at least one card. After ten calendar days, more than 75% of the class was “infected.” In an in-class discussion, the principles behind direct contact transmission were reiterated, and points that the simulation models poorly were also covered: there are not fomites in the simulation; talking does not transmit infectious microbes unless there is droplet transmission; one does not instantly become infectious when infected. Once the exercise had been performed as described above, herd immunity was demonstrated. The Infection Game cards were reclaimed by the instructor. A single card from a separate set of Vaccination Cards labeled either “Immune” or “Not Immune” (Fig. 2) was then distributed to all but one randomly-chosen student. The immunity cards used were a mix of 90% Immune and 10% Not Immune. The single student who did not receive a Vaccination Card was given all the Infection cards and the simulation was repeated. After ten calendar days, there were no new infected individuals. Another in-class discussion described how herd immunity can protect susceptible individuals from infection. Having the students contact the instructor once they are down to a single Infection card gives the instructor some insight as to how the exercise is proceeding. The end date can be delayed or moved up if the dissemination of Infection cards is moving more slowly or more quickly than expected.
CONCLUSION With the recent rise in outbreaks of vaccine-preventable diseases (2, 3), understanding how pathogenic microbes are passed from person to person is more important than ever. The concepts are straightforward enough that a traditional lecture is usually sufficient, but opportunities to let students participate directly in the process, whether in a laboratory environment or in a simulation such as this one, always help solidify ideas. The number of interactions between individuals where infectious organisms could be transmitted is not immediately apparent. This exercise
FIGURE 2. Layout and text of the vaccination cards.
Volume 16, Number 2
helps students realize how much interpersonal contact occurs in daily life. The difference in the rate of infection in a susceptible population and the rate in an immune population is marked and reinforces the importance of immunization not only for personal benefit, but as a societal responsibility. Feedback from students who have participated in this exercise has been positive. They can often deduce that something is going on around them and are excited when they are let in on the “secret” at last. They welcome the chance to have hands-on experiences and are generally surprised by how quickly the “infection” spreads through the class. Simulations have been used in other classrooms from middle school (5) to doctoral programs (8). Scores on assessments after participating in simulation improve (8), and students report having a better understanding of the topic (5).
ACKNOWLEDGMENTS The author declares that that there are no conflicts of interest.
REFERENCES 1. Bay Mills Community College. [Online.] https://www. bmcc.edu/Headstart/Trngds/Diseases/pg7-26.htm. Accessed 24 September 2015. 2. Cherry, J. D. 2012. Epidemic pertussis in 2012 — the resurgence of a vaccine-preventable disease. New Engl. J. Med. 367:785–787. 3. Gastañaduy, P. A., et al. 2014. Measles — United States, January 1–May 23, 2014. MMWR Morbid. Mortal. Wkly. Rep. 63(22):496–499. 4. Leboffe, M. J., and B. E. Pierce. 2010. Microbiology: laboratory theory and application, Third Edition, p 12–13. Morton Publishing Company, Englewood, CO. 5. Neulight, N., Y. B. Kafai, L. Kao, B. Foley, and C. Galas. 2006. J. Sci. Educ. Technol. 16(1):47–58. 6. NIMBioS. 2011. Science Friday Blogs. [Online.] http://www. sciencefriday.com/blogs/09/07/2011/epidemic-the-handshakegame.html. Accessed 24 September 2015. 7. Northern Arizona University. n.d. Modelling the transmission of a communicable disease. [Online.] http:// www2.nau.edu/lrm22/lessons/disease/disease_lab.html. Accessed 24 September 2015. 8. Seybert, A. L., and C. M. Barton. 2007. Simulation-based learning to teach blood pressure assessment to doctor of pharmacy students. Am. J. Pharmaceut. Educ. 71(3):48.
Journal of Microbiology & Biology Education
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JOURNAL OF MICROBIOLOGY & BIOLOGY EDUCATION, December 2015, p. 278-279 DOI: http://dx.doi.org/10.1128/jmbe.v16i2.919
A Simulation of Communicable Disease and Herd Immunity for the Microbiology Classroom or Laboratory Jeff Wiles Department of Natural Sciences, Middle Georgia State University, Macon, GA 31206
INTRODUCTION Although it is reasonably easy and safe to use live organisms in the microbiology laboratory, communicable diseases caused by the transmission of infectious microbes is an important topic that cannot be directly viewed in a laboratory environment. Direct contact transmission exercises (4) using fluorescent dyes such as Glogerm (www. glogerm.com) are useful in teaching the ease of transfer from person to person and the efficacy of proper hand washing. Other simulations use pen and paper to track who has been infected through handshakes during a period when the students are instructed to shake one another’s hands (1, 6). Liquid transfer exercises (7) model sexually transmissible diseases and stress the invisible nature of the infectious agent. None of these model how infections spread in real time from person to person as a consequence of the normal activities they undertake each day. Using a set of cards as proxies for infectious organisms allows students to see how easily and quickly a disease can spread through a susceptible population. After taking part in this exercise, the students should have a clearer understanding of how frequently they are in a situation where microorganisms can be transferred from person to person, how a single infectious individual can inadvertently cause an outbreak, and how vaccination and herd immunity block the spread of communicable diseases. This simulation was designed for use in Microbiology for the Health Sciences, but it should work equally well in high school health or biology classes, introductory college biology courses, or any microbiology course. Additionally, it can be used in a class that does not contain a laboratory portion. The course for which the exercise was designed has a normal enrollment of twenty-four students, but it is expected that both smaller and larger classes should be able to make good use of the simulation. The term “Game” was chosen specifically for this exercise to make it clear to both the participants and to anyone who came across a misplaced set of cards that this is Corresponding author. Mailing address: Biology Department, Middle Georgia State University, 100 University Parkway Macon, GA 31206. Phone: 478-471-2830. E-mail: [email protected].
a purely intellectual exercise and not an act of bioterrorism or other malicious event.
PROCEDURE To prepare for the exercise, a number of small cards roughly equal to the number of students in the class was made. Stiff, brightly-colored paper was used to increase durability and visibility. The small size made them easily portable and easily concealed. A single student in the class was given a large set of identical cards that listed out the rules for how to distribute them (Fig. 1). Keeping the game secret, as described in Rule One, prevented students from altering their behavior to avoid infection. It would be contrary to the goals of the course for students to stop studying in groups, exchanging notes, and helping each other in the laboratory. When the “infected” student came in contact with another student as described in Rule Two, the new student became “infected” as well. They received half of the cards possessed by the first student. Optimally, the original student passing cards on to the new student would also explain the rules. If the infecting student did not explain the game, the newly-infected student at least had the rules from the cards to rely on. Space limitations prevented the inclusion of rules of whether to round up or down when giving cards but this problem was avoided by using 2n cards at the start, where n was the smallest number required for
Welcome to The Infection Game RULE #1 Do not discuss The Infection Game with anyone. It will be a better simulation if fewer people know. RULE #2 If you talk to, touch, or sneeze/cough near one of your classmates, PRIVATELY (Rule #1!!) give them HALF of your infection cards. RULE #3 NEVER give away your last infection card; if you are already infected, DON’T take more cards from anyone. RULE #4 If you have exactly one infection card, email your instructor ASAP – [email protected] FIGURE 1. Layout and text of the infection cards.
©2015 Author(s). Published by the American Society for Microbiology. This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial-NoDerivatives 4.0 International license (https://creativecommons.org/licenses/by-nc-nd/4.0/ and https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode), which grants the public the nonexclusive right to copy, distribute, or display the published work.
278
Journal of Microbiology & Biology Education
Volume 16, Number 2
WILES: COMMUNICABLE DISEASE AND HERD IMMUNITY SIMULATION
each student to be able to end up with at least one card. After ten calendar days, more than 75% of the class was “infected.” In an in-class discussion, the principles behind direct contact transmission were reiterated, and points that the simulation models poorly were also covered: there are not fomites in the simulation; talking does not transmit infectious microbes unless there is droplet transmission; one does not instantly become infectious when infected. Once the exercise had been performed as described above, herd immunity was demonstrated. The Infection Game cards were reclaimed by the instructor. A single card from a separate set of Vaccination Cards labeled either “Immune” or “Not Immune” (Fig. 2) was then distributed to all but one randomly-chosen student. The immunity cards used were a mix of 90% Immune and 10% Not Immune. The single student who did not receive a Vaccination Card was given all the Infection cards and the simulation was repeated. After ten calendar days, there were no new infected individuals. Another in-class discussion described how herd immunity can protect susceptible individuals from infection. Having the students contact the instructor once they are down to a single Infection card gives the instructor some insight as to how the exercise is proceeding. The end date can be delayed or moved up if the dissemination of Infection cards is moving more slowly or more quickly than expected.
CONCLUSION With the recent rise in outbreaks of vaccine-preventable diseases (2, 3), understanding how pathogenic microbes are passed from person to person is more important than ever. The concepts are straightforward enough that a traditional lecture is usually sufficient, but opportunities to let students participate directly in the process, whether in a laboratory environment or in a simulation such as this one, always help solidify ideas. The number of interactions between individuals where infectious organisms could be transmitted is not immediately apparent. This exercise
FIGURE 2. Layout and text of the vaccination cards.
Volume 16, Number 2
helps students realize how much interpersonal contact occurs in daily life. The difference in the rate of infection in a susceptible population and the rate in an immune population is marked and reinforces the importance of immunization not only for personal benefit, but as a societal responsibility. Feedback from students who have participated in this exercise has been positive. They can often deduce that something is going on around them and are excited when they are let in on the “secret” at last. They welcome the chance to have hands-on experiences and are generally surprised by how quickly the “infection” spreads through the class. Simulations have been used in other classrooms from middle school (5) to doctoral programs (8). Scores on assessments after participating in simulation improve (8), and students report having a better understanding of the topic (5).
ACKNOWLEDGMENTS The author declares that that there are no conflicts of interest.
REFERENCES 1. Bay Mills Community College. [Online.] https://www. bmcc.edu/Headstart/Trngds/Diseases/pg7-26.htm. Accessed 24 September 2015. 2. Cherry, J. D. 2012. Epidemic pertussis in 2012 — the resurgence of a vaccine-preventable disease. New Engl. J. Med. 367:785–787. 3. Gastañaduy, P. A., et al. 2014. Measles — United States, January 1–May 23, 2014. MMWR Morbid. Mortal. Wkly. Rep. 63(22):496–499. 4. Leboffe, M. J., and B. E. Pierce. 2010. Microbiology: laboratory theory and application, Third Edition, p 12–13. Morton Publishing Company, Englewood, CO. 5. Neulight, N., Y. B. Kafai, L. Kao, B. Foley, and C. Galas. 2006. J. Sci. Educ. Technol. 16(1):47–58. 6. NIMBioS. 2011. Science Friday Blogs. [Online.] http://www. sciencefriday.com/blogs/09/07/2011/epidemic-the-handshakegame.html. Accessed 24 September 2015. 7. Northern Arizona University. n.d. Modelling the transmission of a communicable disease. [Online.] http:// www2.nau.edu/lrm22/lessons/disease/disease_lab.html. Accessed 24 September 2015. 8. Seybert, A. L., and C. M. Barton. 2007. Simulation-based learning to teach blood pressure assessment to doctor of pharmacy students. Am. J. Pharmaceut. Educ. 71(3):48.
Journal of Microbiology & Biology Education
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