Many of my experts came to the same conclusion, that prions would be a likely culprit in this kind of crisis.
Prions are very nasty little pathogens believed to be the driving force behind a variety of neurodegenerative diseases called transmissible spongiform encephalopathies (TSEs). They’re proteinaceous infectious microscopic particles, meaning that they are proteins similar in some ways to a virus, but prions have no nucleic acid. These diseases slowly attack brain tissue, often leaving spongelike holes (hence spongiform).
Mad cow disease (bovine spongiform encephalopathy) or BSE, is a prion disease affecting cattle. In 1986 an outbreak of BSE was diagnosed in England during which some 178,000 cows were believed to have been infected from a protein feed supplement that contained rendered remains of scrapie-infected sheep brains. Scrapie is a prion disease that affects sheep.
Prion diseases in humans can cause (among other things) loss of balance, disrupted coordination, blindness, dementia, sleep disorders, among other symptoms. All known prion diseases are invariably fatal.
The theory of disease-causing protein particles was established in 1982 by Stanley Prusiner, a neurologist at the University of California at San Francisco, who coined the term prion,5 and who went on to win the 1997 Nobel Prize in Physiology and Medicine for his discoveries.
There are three forms of TSEs affecting humans: sporadic, familial, and iatrogenic.
Sporadic cases strike about one person per million; the cause is unknown, and no treatment for it exists. At the moment these account for close to 85 percent of all TSE cases.
Familial cases, which account for 10 percent of TSEs, are passed down through bloodlines in ways not yet understood since inherited traits are genetic and prions have no DNA. There’s even a version called fatal familial insomnia (FFI), an ultrarare disease found in only a couple of dozen bloodlines worldwide, and in which the victim cannot ever fall asleep, not even when medicated. The victim becomes delusional and erratic, and lingers in a living hell of unending wakefulness until, months later, exhaustion and brain damage causes death.
The remaining 5 percent are iatrogenic cases, which result from the accidental transmission of the causative agent via contaminated surgical equipment or as a result of cornea or dura mater transplants or the administration of human-derived pituitary growth hormones.6
The body’s immune system does not react to prion diseases the way it does to other diseases. The immune system doesn’t kick in and the disease spreads rapidly. Once it takes hold, there is no treatment.
And killing a prion is incredibly difficult. In labs, where growth hormones are cultivated from extracted pituitary glands, solvents of various kinds are used to purify the tissue; these solvents kill everything…except prions. Even formaldehyde won’t kill them. Radiation treatment and bombardment with ultraviolet light doesn’t kill them. Scientists have tried just about everything, including treating diseased brain tissues with all manner of chemicals including industrial detergent—and the prions endure. They don’t even die with the host organism. Bury a corpse with a prion disease and dig up the bones a century later…and the prions are still there. They are, after all, just proteins.
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Art of the Dead—Chad Michael Ward
Rate of Infection
“I think zombie culture speaks to people on a primeval level and people can’t help but be drawn to it. Most zombie tales tend to be end of the world fables and that’s something that’s permeated our culure forever. I’ve always loved the slow, shuffling zombie—very apocalyptic, but the new fast versions cropping up in recent movies bring the fear to a whole new level. In the end, I think I’d have to go with fast.”
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Prions and Cannibalism
One prion disease, kuru, found in the South Pacific, has a frightening link to eating human flesh. Among one tribe in the eastern highlands of Papua New Guinea it was the custom to show respect for deceased family members by eating them. Unfortunately this transmitted the disease from the organs and flesh of the dead to their living—but doomed—relatives. This practice has since been stopped and no further infections have occurred.
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One of the many prion-related areas that has not yet been fully explored is the effect of radiation on prions. If it turns out that radiation in one of its many forms can mutate this disease, then we might be back with Romero’s space probe from Night of the Living Dead. So far, luckily, no evidence supports this.
Prion diseases in animals include:
Bovine spongiform encephalopathy (BSE) in cattle (mad cow disease)
Chronic wasting disease (CWD) in elk, moose, wapati, and mule deer
Exotic ungulate encephalopathy (EUE) in nyala, oryx, and greater kudu
Feline spongiform encephalopathy in cats
Scrapie in sheep
Transmissible mink encephalopathy (TME) in mink
Prion diseases in humans include:
Alpers syndrome, an autosomal recessive, mitochondrial DNA depletion disorder
Creutzfeldt-Jakob disease (CJD) and its varieties:
–Iatrogenic Creutzfeldt-Jakob disease (iCJD)
–Variant Creutzfeldt-Jakob disease (vCJD)
–Familial Creutzfeldt-Jakob disease (fCJD)
–Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common prion disease in humans
Fatal familial insomnia (fFI) is an autosomal dominant inherited disease
Sporadic fatal insomnia (sFI) a noninherited type of fatal insomnia
Gerstmann-Sträussler-Scheinker syndrome (GSS) is associated with autosomal dominant inheritance
Kuru—the word kuru means “trembling with fear” in the language of the Fore people, trembling is a symptom of dying brain tissue
Expert Witness
Dr. B. Burt Gerstman, an epidemiologist from San Jose State University, remarks, “Prions represent unknowns…and people fear unknowns. Prions are strange creatures—they have no DNA but are capable of replication (not reproduction). We still know very little about prion transmission and pathogenesis. We do know they are resistant to routine disinfection and can withstand harsh environmental conditions. I believe they can even survive autoclaving, which is sort of the standard for aseptic technique. These are strange creatures…no DNA yet capable of self-replication under circumstances which we understand relatively little about.”
According to Dr. Pawel P. Liberski7 of the Department of Molecular Pathology and Neuropathology at the Medical University of Lodz, Poland, “Prions do not have DNA. According to the prion hypothesis, a prion is a protein (our own) encoded by a cellular gene. In normal situations—you and me for instance—our prion gene (PRNP) encodes for a normal protein called PrPc (from a cellular isoform8 of prion protein). In abnormal situations, this PrPc changes the shape (technically speaking it is misfolded) into ‘scrapie’ isoform (PrPSc). In people with mutations within the PRNP gene this misfolding occurs spontaneously. If you eat the brain (as in cases of kuru) or you get injected (as in Creutzfeldt-Jakob disease after human growth hormone), the abnormal protein (PrPSc) acts on a normal protein and the normal one is transformed into abnormal protein. It’s a domino effect. How the disease, as in the case of Mad Cow Disease, mutated in humans into variant Creutzfeldt-Jakob Disease (vCJD) nobody really knows. Perhaps passage through an organism (human) different from the original host (cow) somehow change it.”
Dr. Bruno Vincent of the L’Institut de Pharmacologie Moléculaire et Cellulaire9 tells us: “Prions are strongly supposed to be exclusively composed of one protein named PrPsc (for PrP scrapie) that is an abnormal form of the cellular prion protein (PrPc) which is produced physiologically by mammals and non-mammals—and even yeast and fungi.”
Dr. Vincent adds, “Numerous mutations (that occur randomly) associated with this gene have been reported that lead to the development of spontaneous prion diseases. They confer to the mutated prion protein the ability to form aggregates more efficiently and more r
apidly by complex molecular mechanisms. These mutations are rare and account for the so-called inherited prion diseases (genetic forms that are transmitted from parents to children) which represent less than 5 percents of prion pathologies. The remaining cases are either infectious (ingestion of bovine infected meat or cannibalism) or sporadic (that account for 90 percents of prion diseases and for which the cause of PrPc/PrPsc conversion is unknown). The notion of ‘strains’ (several infected brain tissues display distinct incubation times and pattern of neuropathology when injected to mice) is even more puzzling if we referred to the ‘protein only’ hypothesis. This is not due to PrP mutations and is currently under intense investigation in numerous laboratories.”
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Scrapie
Scrapie is a painful and fatal prion disease that attacks the nervous system of goats and sheep. This transmissible spongiform encephalopathy (TSE) is similar to mad cow disease and other related maladies. Scrapie was first recorded in 1732 but to date has not been known to be transmissible to humans.
This TSE disease gets its name from one of its symptoms: Infected animals will frequently rub or “scrape” against fences, rocks, or trees to alleviate an unbearable itch. Other scrapie symptoms include erratic gaits, compulsive lip-smacking, and convulsions.
Scrapies, which has been recorded in England and North America, is incurable, and the only “treatment” is to destroy and cremate the infected animals.
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I asked Dr. Bruno to speculate on whether a prion disease of this kind could be combated. “Numerous pharmacological agents have been shown to slow down or reverse PrPc/PrPsc conversion. Most of these compounds display anti-aggregate properties and prevent the beta-sheet structure of PrPsc. However, the most promising therapeutic against these pathologies is undoubtedly vaccination. Considerable progress has been made in this direction, and, optimistically, a vaccine against prion diseases should be available in the forthcoming fifteen years. Another strategy that could prove useful is to target the cellular prion protein (PrPc) with either PrP RNA antigens or small double-stranded RNA (also called RNAi). In either case, the normal protein is extinguished and the abnormal PrPsc form can no longer replicate because of the lack of the ‘matrix.’”
I asked Dr. Gerstman to help us understand what a “plague” is: “The term plague is used in various ways. There is a specific zoonitic disease called plague—the disease that wiped out half of some European populations in the Dark Ages. With this said, I think ‘plague’ is also used loosely to refer to an epidemic that incites fear.” He goes on to discuss the popular view of what an epidemic is. “This depends on the nature of the epidemic. The term epidemic is general. An ‘HIV epidemic’ is quite different than an ‘epidemic of teen pregnancies.’ However there are many highly contagious diseases. When environmental conditions are right, just about any contagious disease can spread rapidly.”
If it spreads too fast, it’s an epidemic; if it crosses national lines, it becomes a pandemic.
The Zombie Factor
If zombies could come about as a result of a prion disease, how could the disease be stopped? I put this question to my experts.
Dr. Liberski says, “There is no treatment. Certain drugs can interfere with the conversion of normal into abnormal protein, but they are not very efficient. But if you stop the conversion, perhaps the disease can be cured. The goal has not been achieved, however.”
Dr. Vincent, however, says that there are some advances in “nonzombie” prion diseases. He explains, “The recently described human variant of Creutzfeldt-Jakob disease due to the ingestion of contaminated bovine meat as well as the now eradicated Kuru disease which emerged some decades ago in the Fore linguistic group of the eastern highlands in Papua New Guinea and was due to ritualistic cannibalism are the proofs of such a possibility. Thus, the oral route is one way to inoculate humans with prions. Injection in blood is another way to acquire prion diseases since some people contracted Creutzfeldt-Jakob disease following intravenous injections of contaminated growth hormone prepared from bovine hypothalamus. However, we must take into account that both routes in those cases carry small amounts of infectious prions that lead to disease after a long period of time.”
Both doctors maintain that a cure or treatment is not certain and carries with it some considerable risks.
I asked if humans could be inoculated in some way against transmissible prion diseases, but Dr. Liberski didn’t think so. “You must remember, however, that prion is a misfolded normal protein. A vaccine would hurt all forms of that protein.”
Many of the zombie stories talk about an “experimental” pathogen that accidentally escapes a lab. I asked Dr. Vincent to comment on whether a prion could be modified or combined with other pathogens to form a more dangerous pathogen. “Of course it would be feasible to combine prions with other pathogens by laboratory process. However, one should keep in mind that the time-course of prion pathologies following infection could be very long (from several months to 30 years in humans). Thus, prions are far from being a short-term weapon and could at best represent a time-bomb.”
In fiction we have the advantage of considering science somewhat elastic. We can speculate that a laboratory has been working on just such an advanced prion disease and our patient zero was a test subject who escaped. We can also speculate on prion research specifically designed to speed up the infection process, down from months or years to hours. That might be within the limits of possibility, but Dr. Vincent says that the superspeed infection shown in 28 Days Later and the Dawn of the Dead remake are not possible. “On a scientific point of view, the immediate change observed in infected people in zombie-themed films is absolutely impossible whatever the infectious agent considered. If the contamination state (by viruses, bacteria or prion) is effective immediately, it takes time before the symptoms appear: several hours to several days for the most virulent pathogens.”
This lends strong support to Romero’s original vision of a death through infection that lasts several hours.
JUST THE FACTS
Dead Stasis
Our neurologists insist that some part of the zombie’s brain has to be functioning, even at a reduced level, for it to do what a zombie does. The motor functions have to be working, as well as some cognitive ability—after all, the little zombie girl in Night of the Living Dead uses a garden trowel to kill her mother; Bub in Day of the Dead is taught to load a gun, he feels grief, and even speaks a line of dialogue; and Big Daddy in Land of the Dead is the organizer of a very effective zombie revolt. Either these are examples of recovered memories, suggesting that the brains of the zombies are not total organic junk, or they possess the ability to learn—both from their actions and through coaching. Probably both.
The bottom line is that the brain must be preserved after death for a zombie to operate. That is one point we cannot dismiss. If total cellular death occurs, you do not have the potential for a zombie, no matter how strong the virus or other initiating causes. The zombie has motor functions, therefore, some of its brain is working.
This appears to lend support to the working theory that zombies are not entirely (or even actually) dead. Certainly they defy all conventional definitions of dead. Once a human succumbs to the zombie plague, he or she is presumed to be officially dead; but it seems more likely that he or she has actually lapsed into some kind of deep coma state in which most of the body’s functions have stopped but a few (such as the central nervous system) have merely gone into a kind of stasis. There is some support for this in nature.
Expert Witness
The wood frog (lithobates sylvaticus) is the only frog found in the Arctic Circle to freeze solid many times a year and revive unharmed. During the winter as much as 45 percent of the wood frog’s body freezes; ice crystals form beneath the skin and are scattered through the frog’s skeletal muscles. As this happens, the frog stops breathing, its heart stops and there is zero blood flow. By the long-held standards of clinical medici
ne, it is dead. Only it’s not.
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Weird Science: Fido of the Living Dead
There’s just no way to be surprised that this news comes from Pittsburgh, but the Safar Centre for Resuscitation Research in Pittsburgh10 has successfully reanimated dogs several hours after inducing clinical death. The experiment is intended as a step toward a proposed method of flash-freezing severely injured soldiers so they can be transported from battlefield to surgical centers and then successfully reanimated under proper medical and life-sustaining conditions.
The Safar Center has accomplished this with dogs several times and went public with the information in late 2005.
Granted this isn’t the same as reanimating all the dead dogs in the pet cemetery, but when someone in Pittsburgh starts bringing back the dead, anyone in the post-Romero era is going to take notice (and possibly take flight).
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