Agents of Bioterrorism

Pathogens and Their Weaponization

Geoffrey Zubay

• Publisher: Columbia University Press
• Year: 2008
• ISBN:
  9780231518130
• Topic: History
• Subtopic: Military & Maritime History
• Index: History

This new work offers a clear and thorough account of the threats posed by bioterrorism from the perspective of biologists. The authors examine thirteen disease-causing agents, including those responsible for anthrax, the plague, smallpox, influenza, and SARS. Each chapter considers a particular pathogen from the standpoint of its history, molecular biology, pathology, clinical presentation, diagnosis, weaponization, and defenses. The book also examines strategies for making vaccines and protecting the population in a bioterror attack.

CHAPTER 1

TERRORISM AND FEAR

HOW TO COPE

Geoffrey Zubay

Fear is the currency of terrorism. It comes in a variety of forms: fear of dying, fear of being crippled, fear of the unknown. To reassure Americans in a day of confusion after the attack on Pearl Harbor, President Roosevelt said they had nothing to fear but fear itself. Because ignorance and insecurity are prime ingredients of fear, the more we know about a particular terrorist event the lower its fear potential is likely to be and the sooner we are likely to find a constructive solution.

This book is dedicated to presenting a comprehensive picture of what bioterrorism is all about and how we can defend ourselves against it. Our belief is that knowing what we are confronting will help to minimize fear and encourage productive behavior.

An effective terrorist knows how to plan his acts of terror so that they have maximum impact. He must be highly motivated and willing to make personal sacrifices. It is hard to think of a more effective act of terror than was committed at the World Trade Center in New York City on September 11, 2001, when a handful of terrorists brought down the symbols of American economic power and killed over 3000 people of different nationalities. More were killed by this small group than in the Pearl Harbor attack conducted by a naval battle group. Furthermore, the September 11 event produced enormous fear in the aftermath as we came to realize how vulnerable our society is to attacks of this nature, and we have since lived in fear of another attack. The World Trade Center terrorists were very effective; they had a workable plan and they were willing to die for it.

AMERICA AS A TARGET FOR TERRORIST ACTIVITIES

There are numerous reasons why the United States has become a terrorist target. Some are obvious, others more subtle. Among the factors are our great wealth, which breeds resentment leading to hatred; our use of military power; our support for totalitarian governments; our support for democracy; our liberal culture; and our strategic dominance after the end of the Cold War. The United States is thus a likely target of terrorists who may disapprove of U.S. policy or culture or who are directly opposed to purported Western ideals. It should be noted that not all terrorists are foreigners—the “Unabomber” and Timothy McVeigh’s 1995 bombing of the Federal Building in Oklahoma City are examples of home-grown terrorists. Nor may they have any intelligible reason for terrorist acts: the Aum Shinrikyo cult’s nerve-gas attack in the Tokyo subway reflected a hopelessly muddled apocalyptic world view.

BIOLOGICAL AGENTS IN TERRORISM

A terrorist’s goals may be met with various agents. Explosives are the most common type of weapon used by terrorists. Terrorist activities that employ biological agents have been largely ignored, probably because the use of explosives has been so successful. Another factor is that the handling of biological agents requires new kinds of skills. Whatever the explanation in the past, it seems highly likely that the use of biological agents will increase in the near future because they are easier to hide, cheaper, and far more devastating. More attention must be given to the likelihood of increased use of biological agents by terrorist groups.

We might ask whether bioterrorism is something new or something recently conceived. The answer is that it is as old as recorded history, as seen in subsequent chapters. What distinguishes contemporary bioterrorism are the scientific advances that have been made in our understanding of how pathogens produce their toxins and how we can protect ourselves against them. On the one hand, this has also resulted in the discovery of a wide range of new bioweapons. On the other hand, this has resulted in the discovery of procedures for protecting against serious pathogens.

NATURE: AN EXQUISITE BIOTERRORIST

Nothing engenders more fear than the thought that when you go outside you may encounter a deadly pathogen that will result in an agonizing illness followed by death. One should keep a sense of proportion. Thus far, at least, the agents of bioterrorism look rather puny in their impact. In terms of kill power, only about 10% of all deaths result from infectious disease, either directly or indirectly. That means that, in a world of 6 billion people with an average life expectancy of 60 years, about 10 million people will die every year from an infectious disease. Currently the three major killers are the human immunodeficiency virus (HIV), tuberculosis, and malaria, which account for, respectively, 3 million, 2 million, and 1 million deaths per year. It should be noted that none of these is considered an agent of bioterrorism and that bioterrorist events have never resulted in more than a few thousand deaths in a single episode.

A major reason that HIV, tuberculosis, and malaria are not considered likely agents for bioterrorism is that their action takes many months, or even years, to be felt. Most agents used by bioterrorists are effective in a matter of hours or days. Thus, time to impact appears to be an important component of bioterrorism.

THE RANKING OF BIOWEAPONS

The Centers for Disease Control and Prevention (CDC) is the agency within the U.S. Department of Health and Human Services whose job it is to protect American citizens from infectious diseases. They have ranked biological agents based on the dangers they pose and the likelihood that they will be used as agents of bioterrorism. Category A agents are easily disseminated and/ or highly infectious and are characterized by high mortality rates. Because of their speed of action, they are likely to strain the public health infrastructure if released. In addition, many are untreatable or difficult to treat and could cause public panic. Category B agents are considered lower in priority because of their lower mortality rates and the ease with which they can be treated. Category C agents are emerging pathogens considered to have a potential for weaponization due to their potentially high morbidity and mortality rates and their availability.

Classification schemes may change as we learn how to cope with existing pathogens or as terrorists learn how to make available pathogens more deadly. For example, Vibrio cholerae, which is now classified as a Category B agent, would once have been considered a Category A agent until it was learned that simple hydration therapy lowers its lethality from 50% to 1% On the other hand, anthrax might have been classified as a Category B agent until procedures for producing powdered spores gave it greater stability and potency.

Subsequent chapters deal with six pathogens classified as Category A threats: anthrax, smallpox, Ebola virus, Francisella tularensis, Yersinia pestis, and Clostridium botulinum. In addition, three Category B agents—V. cholerae, salmonella, and viral encephalitis—and one Category C threat—hantavirus—are discussed. Finally, two agents that have not yet been classified—the viruses that cause influenza and the severe acute respiratory syndrome (SARS)—are examined. The latter seems to have come out of the rural area of western China.

THE LITERATURE ON BIOTERRORISM SHOULD NOT BE CENSORED

There is a movement by scientific journals to censor submissions dealing with bioterrorism-related research. The idea that such articles may pose more risk than benefit to our security is one that must be considered seriously as it could have a significant impact on the kind of research that is conducted. It is my view that such a censorship program would do more harm than good. It seems unlikely that it would inhibit the clandestine efforts of terrorists to weaponize and distribute deadly pathogens. But it would surely bring an abrupt halt to most of the efforts of well-intentioned researchers to find ways of dealing with such pathogens. The unrestricted flow of scientific ideas and information is critical to the advancement of science. Therefore, if science in the area of bioterrorism is to advance, scientists involved in this research must be free to conduct and publish their results.

The vast majority of these scientists do not conduct research relating to bioterrorism in order to make weapons but rather to devise ways to defend against them. An official policy of suppressing publication of this work would only put a damper on potentially life-saving research. If we are not encouraged to study these organisms, we are unlikely to learn how to counter them. I am very optimistic that, given the opportunity, we will find ways to counter the deleterious effect of weapons that might be used by bioterrorists. Perhaps this is because I believe that good scientists far outnumber scientists with evil intentions, and that by and large good scientists are smarter.

CHAPTER 2

VIRAL ENCEPHALITIS (FLAVIVIRUSES)

Salwa Touma

The viral genus Flavivirus is a very serious public health threat. Twenty-two of the 34 mosquito-borne flaviviruses cause human disease.² In some strains, the flavivirus enters the brain’s blood vessels and nerves and causes brain inflammation, which is known as encephalitis.³ In the most severe cases, this inflammation may cause debilitating irreversible nerve damage, brain tumors, and death.⁴ The lethality of encephalitis can be as high as 37%, although it varies by strain.³

There are some prophylactic measures against viral encephalitis and one synthetically created acyclic nucleoside analog, Acyclovir,^1–3 and many companies are working to develop a vaccine. However, since such a vaccine does not currently exist for the most common strains of encephalitis in the United States, it is a major bioterrorist threat. Its danger is increased by the ease of transmission from mosquitoes (mainly the culex species) and ticks and by their many breeding grounds.^1,5 However, because of its moderate to low mortality rate, its moderate ease of dissemination, and the fact that it requires specific enhancements of the Centers for Disease Control and Prevention’s (CDC) diagnostic capacity and enhanced disease surveillance, the CDC categorizes viral encephalitis as a Category B bioweapon threat and a Biosafety Level 3 pathogen.³

Encephalitis is derived from the Greek word encephalo (“brain”) and the Greek word itis, a term used pathologically to indicate inflammation of an organ or an abnormal state or condition. Thus, taken together, encephalitis literally means “inflammation of the brain,” which is precisely what advanced encephalitis is and what causes its potential lethality. However, unlike meningitis, which is limited to inflammation of the meninges of the brain, encephalitis involves inflammation of both the meninges and the parenchyma^1,7,12,18 (figure 2.1A and B).

FIGURE 2.1. Encephalitis involves inflammation of the meninges (A) and the parenchyma (B). Neurons are surrounded by cerebral spinal fluid (CSF) (C). Encephalitis enters the CSF from the blood through the blood–brain barrier, which is normally closed to prevent the flow of materials from the blood into the brain. However, the barrier is opened by nasopharyngeal mucous membrane congestion when the body wages a general immune attack against encephalitis.

STRAINS OF ENCEPHALITIS AFFECTING THE UNITED STATES

Reported cases of different strains of viral encephalitis are genetically conserved and have been confirmed globally. The focus of this chapter is the viral genus Flavivirus within the viral family Flaviridiae. Flavivirus comprises two of the most widely occurring strains of viral encephalitis in the United States: St. Louis encephalitis (SLE) and West Nile encephalitis (WNE)^6,8,10,13,16 (figure 2.2).

Viral encephalitis in the United States can be divided into five strains: SLE, WNE, Eastern equine encephalitis (EEE), Western equine encephalitis (WEE), and La Crosse encephalitis (LCE). The names of the five strains are based on the location of the first identified outbreak and in some cases are based on the region of the resulting outbreaks. SLE, first seen in Paris, Illinois, has been reported throughout the United States. WNE, initially in the West Nile province of Uganda, first seen in New York City in 1999, has been reported throughout the United States. Cases of EEE, first seen in Massachusetts, have been reported elsewhere in the eastern United States. WEE, first identified in California, has been reported in the western and central United States. Finally, LCE, first seen in Wisconsin, has been reported in the eastern United States. Clearly, regardless of the location of the first reported case, each strain quickly spreads throughout a region. In the case of WNE, the strain rapidly moved from east to the west over the course of 4 years, from 1999 to 2002^6,8,10,13...

Table of contents

• Cover 
• Half title
• Title
• Copyright
• Contents 
• Preface
• List of Contributors
• Chapter 1. Terrorism and Fear: How to Cope
• Chapter 2. Viral Encephalitis (Flaviviruses)
• Chapter 3. Botulism (Clostridium botulinum)
• Chapter 4. Tularemia (Francisella tularensis)
• Chapter 5. Ebola Viruses
• Chapter 6. Influenza Virus
• Chapter 7. Hantavirus
• Chapter 8. Anthrax (Bacillus anthracis)
• Chapter 9. Severe Acute Respiratory Syndrome (SARS)
• Chapter 10. Plague (Yersinia pestis)
• Chapter 11. Smallpox (Variola Virus)
• Chapter 12. Cholera (Vibrio cholerae)
• Chapter 13. Salmonella
• Appendix 1. Drug Discovery and Biodefense
• Appendix 2. The Search for Vaccines
• Appendix 3. Personal Biodefenses
• Appendix 4. Information Resources on Bioterrorism
• Glossary
• Index