Editors: J.M. Tchuenche and C. Chiyaka, pp. 133-150 2009 Nova Science Publishers, Inc.
W HEN Z OMBIES ATTACK !: M ATHEMATICAL
M ODELLING OF AN O UTBREAK OF Z OMBIE
Philip Munz1 ∗ Ioan Hudea1 † Joe Imad2 ‡ Robert J. Smith?3 § ,
School of Mathematics and Statistics, Carleton University,
1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
Department of Mathematics, The University of Ottawa,
585 King Edward Ave, Ottawa ON K1N 6N5, Canada
Department of Mathematics and Faculty of Medicine, The University of Ottawa, 585 King Edward Ave, Ottawa ON K1N 6N5, Canada
Zombies are a popular ﬁgure in pop culture/entertainment and they are usually portrayed as being brought about through an outbreak or epidemic. Consequently, we model a zombie attack, using biological assumptions based on popular zombie movies. We introduce a basic model for zombie infection, determine equilibria and their stability, and illustrate the outcome with numerical solutions. We then reﬁne the model to introduce a latent period of zombiﬁcation, whereby humans are infected, but not infectious, before becoming undead. We then modify the model to include the effects of possible quarantine or a cure. Finally, we examine the impact of regular, impulsive reductions in the number of zombies and derive conditions under which eradication can occur. We show that only quick, aggressive attacks can stave off the doomsday scenario: the collapse of society as zombies overtake us all.
A zombie is a reanimated human corpse that feeds on living human ﬂesh . Stories about zombies originated in the Afro-Caribbean spiritual belief system of Vodou (anglicised ∗
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Philip Munz, Ioan Hudea, Joe Imad et al.
voodoo). These stories described people as being controlled by a powerful sorcerer. The walking dead became popular in the modern horror ﬁction mainly because of the success of George A. Romero’s 1968 ﬁlm, Night of the Living Dead . There are several possible etymologies of the word zombie. One of the possible origins is jumbie, which comes from the Carribean term for ghost. Another possible origin is the word nzambi which in Kongo means ‘spirit of a dead person’. According to the Merriam-Webster dictionary, the word zombie originates from the word zonbi, used in the Louisiana Creole or the Haitian Creole. According to the Creole culture, a zonbi represents a person who died and was then brought to life without speech or free will.
The followers of Vodou believe that a dead person can be revived by a sorcerer . After being revived, the zombies remain under the control of the sorcerer because they have no will of their own. Zombi is also another name for a Voodoo snake god. It is said that the sorcerer uses a ‘zombie powder’ for the zombiﬁcation. This powder contains an extremely powerful neurotoxin that temporarily paralyzes the human nervous system and it creates a state of hibernation. The main organs, such as the heart and lungs, and all of the bodily functions, operate at minimal levels during this state of hibernation. What turns these human beings into zombies is the lack of oxygen to the brain. As a result of this, they suffer from brain damage.
A popular belief in the Middle Ages was that the souls of the dead could return to earth one day and haunt the living . In France, during the Middle Ages, they believed that the dead would usually awaken to avenge some sort of crime committed against them during their life. These awakened dead took the form of an emaciated corpse and they wandered around graveyards at night. The idea of the zombie also appears in several other cultures, such as China,...