Mad Dogs and Chicken Heads
Modelling Disease Outbreaks and Vaccination Campaigns
School of Biological Sciences
The University of Manchester
Although rabies still causes thousands of deaths globally every year, it has essentially been eradicated from most industrialized countries. Part of the success story is due to an unusual project undertaken by the Swiss prompted by a series of large outbreaks in the 1970s: the large-scale vaccination of wild foxes to stop the epidemic. In this directed case study, students use an easily accessible MS Excel-based model to understand key epidemiological parameters of rabies outbreaks in wild foxes. The simple model allows students also to predict what proportion of foxes needs to be vaccinated to eradicate the virus from the population. The case fits into both ecological and microbiological (epidemiological) courses and offers opportunities to explore zoonotic diseases and "One Health" questions. The mathematical basis of the differential equations in the models is explained, although prior knowledge of calculus is not essential. A key learning outcome is the critical understanding of both the power and limitations of simple epidemiological models. This case was written for an online course but could also be used as a face-to-face activity if students have access to computers in class.
- Define what zoonotic diseases are and explain how animal disease carriers complicate the management of epidemics.
- Describe what the key parameters used in epidemiological modelling mean: transmission coefficient, recovery rate, latency period, basic reproductive number R0, and critical population size ST.
- Critically discuss the simplifying assumptions, predictive power, and limitations of simple epidemiological models.
- Interpret the patterns predicted by an epidemiological model in a biologically meaningful way.
- Explain how an epidemiological model can guide public health policy; specifically, advise what proportion of foxes needs to be vaccinated to eradicate the rabies virus from a population.
KeywordsEpidemiology; mathematical modelling; SIR model; rabies; vaccination; zoonosis; One Health; wildlife disease; fox; foxes; transmission coefficient; recovery rate; latency period; basic reproductive number; critical population size
Educational LevelUndergraduate lower division, Undergraduate upper division
FormatPDF, PowerPoint, Excel
Type / MethodsDirected, Laboratory
Subject HeadingsBiology (General) | Ecology | Epidemiology | Wildlife Management |
Case teaching notes are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.
Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.
See the case study teaching notes for details on the use of the PowerPoint presentation and two Excel workbooks below.
rabies_epidemiology_2.xlsx (~8 MB)
Answer keys for the cases in our collection are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.
The following video(s) are recommended for use in association with this case study.
- The Strange—but Necessary—Task of Vaccinating Wild Seals
Vaccination of endangered Hawaiian Monk seals against morbillivirus in the wild. Running time: 2:59 min. Produced by National Geographic, 2016.
- Introduction to an Infectious Disease Model, Part I
Simple introduction to the ideas behind an SIR infectious disease model and its dynamics. Running time: 11:10 min. Produced by Duane Nykamp, 2013.
- Week 1 Video 5: Reproductive Number
A brief and clear explanation of the epidemiological parameter R0. Running time: 4:49 min. Produced by Center for Infectious Disease Dynamics, 2014
- Rabies in a Human Patient
Case history of an Iranian patient bitten by a rabid wolf. 1961[?] educational film. [Warning: graphic content.] Running time: 3:31 min. Produced by D M Reynolds; University of California (System) Extension Media Center (OCLC Number: 220258689), 2012.
- Course of Fox Rabies and its Elimination in Switzerland
Rabies cases 1967-1999 mapped onto physical map of Switzerland. Suggest to play at 2x speed. Running time: 7:09 min. Produced by girasouls, 2012.