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Defense Against Biological Terrorism
by Torsten Sohns
German Armed Forces Medical Academy
Neuherbergstr. 11, D - 80937 Munich

This article examines the possible dangers to civilians posed by biological warfare (BW) agents in the hands of terrorists, "bioterrorism" and provides suggestions on appropriate defensive measures. Bioterrorism is a reality, for which, unfortunately, most countries are ill prepared. Although top priority must be given to ensuring that bioterrorism does not happen, it is equally important to enhance readiness for BW defense. In many countries bioterrorism defense is not the duty of the armed forces, but the responsible state agencies must rely on them because of their expertise in BW defense activities, and, because most qualified full-time biodefense experts are in the armed forces.

When estimating the risks of bioterrorism, we look at both the characteristics of possible risks and the probability of such an occurrence. The bioterrorism risk is a function of the presence of terrorists and the probability that they possess the ability to employ a BW agent. A risk exists if there are terrorists who have access to BW agents. Additional risk factors include the existence of vulnerable targets and the potential damage that can be inflicted. The risk becomes a threat once terrorists have specific intentions of employing BW agents. Such intentions may be the result of international and sociopolitical interactions or the personal situation of a lone fanatic. Have terrorists (either state sponsored or organized groups or individuals) ever succeeded in gaining possession of BW agents? Unfortunately, the answer to this question is yes. There have been several examples around the world in the 1980s and 1990s: in Paris Clostridium botulinum cultured by the West German Red Army Faction; [1]; in northwest Oregon, USA, deliberate salmonella bacteria contamination of food in restaurants [2]; across the border from Alaska to Canada, ricin smuggled [3,4,5,6]; in the USA, individual ordering of Yersinia pestis from American Type Culture Collection [7]; in Tokyo, the Aum Shinrikyo sect prepared to use anthrax spores and botulinum toxin. An exhaustive review was published by Carus. [8] The US FBI at any given time has about 50 to 60 ongoing investigations connected with bioterrorism. [9] There is no question that vulnerable targets exist. Even the response to a bioterrorist threat is time and labor intensive. In one incident, 800 people were quarantined inside of a nightclub for hours. In another incident, 24 December 1998, 200 people in a shopping center had to remove their clothes and be rinsed with bleach. [10] The response to such threats is real and must be implemented before determining whether or not the threat is real or a hoax.

1.1 Distinctive Characteristics of BW Agent Operations
BW agent attacks can cover a wide area. Dissemination experiments involving microorganisms conducted several decades ago showed that an area of 100,000 km2 could be contaminated without difficulty from an airplane. BW attacks can be carried out covertly. BW agents can be combined with radionuclides and chemical agents, which would complicate identification and treatment of the agents. For example, UNSCOM [11] sources have reported evidence that Iraq was prepared to add BW agents to chemical weapons. Unlike other weapons, BW agents mimic naturally occurring diseases. A BW attack may be formally proven only after natural causes for any unusual cases of disease and death have been ruled out. BW agents propagate and can cause epidemics. No other warfare agent can multiply after it has been used. Animals (humans, too) can become reservoirs and carriers of pathogens and contribute to the preservation, spread or formation of new epidemic centers.

1.2 Accessibility of BW Agents
Particularly virulent and environmentally resistant strains of dangerous pathogens can be suitable as BW agents. The majority of them occur naturally in animal reservoirs. When used as a BW agent, the pathogens are likely to be dispersed as aerosols to quickly infect the greatest number of people. Victims would be infected through their respiratory tract, probably by a massive dose of BW agent. Dangerous poisons of biological origin, toxins, are also suitable. Botulinum toxin, for example, is about 15,000 times more poisonous than the deadliest chemical agent, VX, and 100,000 times more poisonous than sarin. [12,13] Table 1 lists the "Dirty Dozen" toxins and diseases suitable as BW agents for terrorist actions. Others are possible, but these are the ones with properties most suitable for release or dispersion in weapons of mass destruction (WMD). This table does not include other agents capable of killing or damaging plants and animals. These agents, which are not dangerous to man, may be used for economic motives. To evaluate the risks posed by bioterrorism, it is important to estimate the capability of potential perpetrators to gain possession of such pathogens and toxins. The agents vary from the relatively easily produced ricin to bacteria and to specialty viral agents. Specially trained technicians, under carefully controlled conditions, can produce viral agents. There are also limitations to the use of bacterial pathogens, but these are easier to overcome. Although many pathogens are present naturally, it is difficult to obtain an especially virulent and environmentally resistant strain of a given pathogen. Having acquired the pathogen and learned how to mass-produce it, the perpetrators would then have to decide, whether or not to use it in crude form and accept what in military terms would be low efficiency but for terrorist purposes would probably sufice. The other choice would be to refine the agent, i.e., to dry the pathogens and process them into an inhalable dust. The particles must be coated to protect them in the air so that they can drift for many kilometers. This choice requires sophisticated skills and equipment, but a determined individual or groups would be able to accomplish this.

1.3 Dissemination systems for BW agents
Knowledge of the logistic capabilities and likely dissemination systems of potential perpetrators also provides useful information for risk evaluations. Aircraft, in particular agricultural airplanes with spraying equipment, drones, ground and marine vehicles, can be used by terrorists to disseminate BW agents. On the ground, aerosol generators could be carried almost anywhere in a covered automobile trailer. No one would notice if, for instance, anthrax spores were blown into the central air-conditioning unit of a mall or an office building. Drinking water supply systems can also be used to disseminate BW agents. Not all BW agents can be removed or deactivated with normal purification systems, including boiling.

1.4 Potential Perpetrators
Fortunately so far there have been only a few uses of bioterrorism. [14] In general, political or fanatical motives may prompt the use of bioterrorism. We can estimate the risk of bioterrorism by correlating the background of potential terrorists and their access to BW agents. Table 2 lists the category of terrorism along with the likely motives for using bioterrorism. According to unclassified literature, some 15 countries are suspected to be conducting biological activities at variance with the Biological and Toxin Weapons Convention (BTWC). [15] These countries are listed in Table 3. [16] Information is available about the pathogens and toxins that are being worked on in so-called "rogue countries." Several of these countries are also suspected of supporting international terrorism. The nationality of terrorists could therefore tell us something about the BW agents to which they have access. On the other hand, these countries would come under immediate suspicion if a terrorist attack employed a BW agent presumed to be in their arsenal. This may pose a considerable political, economic and military risk for such states. For this reason, there is a strong motive for most states to not supply terrorists with BW agents. Risk estimates are even more difficult when evaluating the BW capabilities of terrorist groups, sects or even individuals. The capability of these groups to acquire or produce BW agents has been verified by events in Japan and the USA. [19]

1.5 Potential Targets
Finally, an assessment of risks must also include an analysis of potential targets. Terrorist attacks are likely to be directed at major cities, areas of particular significance for the economy, transport or the military (e.g., trade fairs, shopping malls, ports, airports), assembly facilities (e.g., municipal halls, sport stadiums) and artificially ventilated buildings (e.g., government, parliament or court buildings and, most particularly, subway systems). [20] Even individuals can be the targets of insidious BW agent attacks. [21]

1.6 Dangers to the General Public
What are the risks and dangers posed to the general public? The effects of BW agents vary considerably. Some pathogens and toxins can cause fatal diseases, as in the case of pulmonary anthrax or botulism, but are not necessarily infectious. There are, however, BW agents that cause communicable diseases and can trigger epidemics. Smallpox poses such a danger. Because systematic vaccination against smallpox has ceased, any epidemic resulting from a smallpox bioagent will spread rapidly and be highly lethal, unless immediate quarantine measures and vaccination to prevent the infection from spreading are taken. Other pathogens, such as Q fever, would incapacitate but not kill their victims, unless they were immunocompromised. How much would a terrorist need? In 1970 an expert commission of the WHO published model calculations for the dispersion of 50 kg of anthrax spores, sprayed from an airplane over a city with 500,000 inhabitants. [22] This model predicted 95,000 dead and 125,000 cases of illness or 50 kg of anthrax spores would kill almost one-fifth of the inhabitants; these losses are comparable to those inflicted by an atomic bomb attack. At the beginning of the Gulf War, Iraq had produced and weaponized 6000 to 8000 kg of anthrax spores, as well as 19,000 kg of botulinum toxin. [23] Iraq produced more than 100 times the amount of anthrax as in the model calculation. The whereabouts of these weapons have not been determined or explained.


2.1 Prevention
Through continuous monitoring, analysis and evaluation of suspicious activities, people, organizations and states, by intelligence services and biodefense experts, we can better recognize the dangers posed by bioterrorism. This knowledge increases our chances of preventing terrorist actions. It helps recognize, at an early stage, the intentions of terrorist groups and unaffiliated individuals. Close international and national cooperation among intelligence services and criminal investigation departments, with the expertise of BW defense experts, is necessary. In most countries, there is only a handful of scientifically trained people, working full-time on BW defense. With few exceptions, they are armed forces personnel.

2.2 Operational Control
Once the threat or use of BW agents has occurred, operational control must be given to a center with clearly defined responsibilities and powers, already established at the highest appropriate level. Details of the operations should have been rehearsed before an actual threat occurs. Biodefense experts should be immediately available to the operations center. BW agent aerosols can be disseminated over large areas. For this reason, as in a radiological crisis situation, immediate information exchange with neighboring countries may be necessary. This, along with the necessity of coordination operations and resources across multiple agencies and jurisdictions requires the center to be at the highest level.

2.3 Situation Assessment
Information coming from ambulances, hospitals and emergency rooms may provide the first indications of a bioterrorist attack. Patient symptoms and the results of initial laboratory tests will give preliminary information about the type of BW agent used. By asking patients about their whereabouts at the presumed time of exposure, it is possible to roughly establish the area of use and the zones of dissemination of the BW agent. As soon as possible, it must be determined whether a communicable disease is involved and which areas are still or already contaminated or endangered. Local residents must be warned and, if necessary, evacuated or quarantined.

2.4 Outbreak Management
In the case of the threatened or actual release of communicable disease agents, the operations control center must prepare or carry out effective outbreak management. This includes the planning and control of all necessary anti-epidemic measures. The timeliness and quality of these measures can control an epidemic and prevent a secondary epidemic.

2.5 Public Relations, Evacuation, Traffic Control and Vulnerable Point Protection
To prevent panic and avoid confusion, only the operations center should provide information to the public. In the event of an unspecified BW terrorist threat, vulnerable point protection should concentrate on ventilation systems of densely populated buildings, as well as on infrastructure of central water supply systems.

2.6 Biological Agent Detection and Identification
The rapid identification of contaminated areas is critical to assessing the situation and deciding appropriate action. For this purpose, detection teams must inspect the areas in question for traces of BW agents. However, satisfactory methods for rapid detection and identification of BW agents is still a long way off.

2.7 Medical Treatment
Many doctors are unfamiliar with the symptoms and treatments for the "Dirty Dozen" toxins and diseases. Treatments can vary from vaccinations, to antisera, antibiotics, antidotes, supportive treatment and isolation. The simultaneous occurrence of a large number of serious cases will result in logistical and infrastructural bottlenecks. These may be aggravated by the need for heightened protection and isolation measures to prevent secondary epidemics and by loss of medical personnel and transport problems caused by panic. It is critical that biodefense experts help train and be a resource for the civilian medical system. It is also important that rapid logistical access to medicines, including vaccines, sera, antibiotics, etc., be coordinated by a national authority that will report to the operations center.

2.8 Verifying a BW Attack
If unusual diseases and deaths occur, there are two main questions. First, what is the identity of the pathogen or toxin? And second, are the diseases or deaths the result of a BW agent or do they have a natural cause? Rapid identification is required so that specific countermeasures can be taken. Even if someone claims responsibility for a BW agent attack, government bodies must still conduct a critical examination of the case and look for concrete evidence. This is important to assessing the situation and making decisions about further action. Verification results may be used to justify serious political or even military measures. To clarify this scenario, there must be close and professional cooperation between a wide variety of personnel and resources, in particular biodefense experts, health care services, police and intelligence services. The first indications of a BW agent attack can appear within a few hours in hospitals, when physicians are suddenly confronted with a large number of patients all showing synchronized symptoms of an unusual, largely unknown disease. Further important data for the identification of the pathogen or toxin will come later - after days and, in some circumstances, even after a delay of months [24-25] - from domestic and foreign laboratories in which identification or differentiation has been conducted. In addition to analyzing air, water, soil and other samples, particular attention must be paid to human and animal specimens including corpses, carcasses, parasites and vectors. Special training and equipment are required for collecting and evaluating samples. Such diverse analyses necessitate special skills and safety requirements that may not always be available in the country. Verification of a pathogen strain, which has never before appeared in the region concerned, can be a particularly powerful piece of evidence indicating a possible BW agent attack.

2.9 Other Countermeasures
Many more measures must be addressed. Because of space constraints, only the most important ones are highlighted here: Individual protection, collective protection, hardening of equipment, decontamination, marking, cordoning off and guarding hazardous areas, technical warning systems, and support provided by the armed forces.


Biological terrorism is a reality. The chances of it occurring now are greater than they were in the past. The question is no longer whether, but when. The vulnerability of our highly civilized and technological world to bioterrorism is considerable. If it is difficult to protect armed forces in operations against BWs, then protecting the civilian population poses even greater problems. Conceptual gaps and financial deficits are clearly evident. Prevention and mitigation arethe two keystones in any bioterrorism countermeasures program.

3.1 Prevention
Political means first must be used to eliminate the causes of terrorism, to prevent the development, production and stockpiling of BWs and to monitor the proliferation of BW technology by non-proliferation and export control measures. National intelligence services must cooperate in the pursuit of suspicious persons and material worldwide. In cooperation with friendly countries, we must support the Russian government in converting the former Soviet military BW research and production facilities. This will help to reduce the number of former BW scientists who might need to go elsewhere or sell their expertise and equipment in order to support their families. [26,27] Furthermore, access to potential BW components should be made difficult on both the international and national levels: First, export control measures can help counter the risk of misuse of biological substances and dual-use equipment. Such material and equipment should only be supplied to countries which are known to comply with the Biological and Toxin Weapons Convention and allow inspectors free access. Second, on the national level, authorities issuing handling or export permits for dangerous pathogens or approving the operation of laboratories with enhanced safety, need training and regular information updates on the military and dual-use technological activities and uncovered cases of biological terrorism. The same applies to customs authorities, law enforcement agencies, relevant industrial associations, and scientific institutes. Finally, training programs for intelligence personnel and criminal investigation officers can improve prevention. Their agencies must work closely together in an effort to prevent bioterrorism.

3.2 Mitigation
Prevention reduces but does not eliminate risks. Consequently both civilian authorities and the armed forces must be prepared to take necessary action to avert hazards in the event of a threat or actual use of BW agents by terrorists. Using their BW defense experts, the armed forces should provide training programs for police officers, firefighters, key law enforcement and health personnel, as well as for relevant personnel from governmental and non-governmental aid organizations (e.g. Red Cross). Studies should be commissioned to analyze possible bioterrorist scenarios, identify particularly vulnerable points (e.g., the ventilation systems of large buildings, malls, etc.) and find the best ways of preventing and dealing with bioterrorist attacks. Civilian and military authorities must keep each other informed about their capabilities. Action by civilian authorities and the armed forces must be planned, coordinated and exercised together. Appropriate judgement and action in the face of BW hazards is possible only with the support of BW defense experts. In most countries, political and administrative decision makers are dependent on the expertise of the armed forces. The necessary funds must be apportioned to the armed forces. Vaccination policy remains an open issue. Since highly contagious diseases may rapidly spread worldwide, vaccination policies should be dealt with on an international basis. An initiative should be started to aim at ensuring the timely availability of licensed vaccines in sufficient quantities when needed as well as a common approach for vaccination. This includes such issues as vaccination of medical emergency crews, availability of e.g. smallpox vaccine for containing an epidemic and others. In most countries there are far too few facilities for the special diagnosis and therapy of dangerous, communicable diseases, regardless of possible cause. The same applies to the transport of highly contagious patients. Disaster prevention should give a high priority to determining the required number and location of biosafety level BL3 and BL4 facilities. Urgent research and development requirements include automatic detection and monitoring systems, expansion of the spectrum of detectable BW agents, shortening of the detection time, and improving the specificity and sensitivity of methods. Rapid and effective prophylactics and therapeutic modalities must be found for all relevant BW agents. [28] An open and balanced information program about the dangers of BWs and their proliferation, as well as on the requirements for funding and the progress of counterprograms should be instituted. In many countries, increased budgeting is mandatory for counterprograms to improve understanding and reduce the risks and probabilities of bioterrorism attacks.

Key Words: Risk, NBC, biological, chemical, proliferation, bioterrorism, casualty, resources, medical personnel, medical materiel, decontamination

About the author: Colonel Sohns is a medical officer with the German Armed Forces. In the recent past he has worked in the fields both of medical planning and policy and of NBC medical defense. He is currently Deputy Commander of the German Armed Forces Medical Academy. Prior to this, he was assigned to the German Ministry of Defense and to NATO's Supreme Headquarters Allied Powers Europe (SHAPE).

Ed. Note: Col. Sohns' previous paper, which was published in ASA issue 99-3 (June 1999), provided an in-depth study on the proliferation of weapons of mass destruction. Our thanks to Col. Sohns for both studies; they greatly add to our baseline of understanding across these critical areas.


  1. R. Purver (Canadian Security Intelligence Service), "Chemical and Biological Terrorism: The Threat According to the Open Literature," printed as a manuscript, June 1995
  2. T.J. Tšršk et al, "A Large Community Outbreak of Salmonellosis Caused by Intentional Contamination of Restaurant Salad Bars," JAMA, 6 August 1997, Vol. 278, No. 5, 389-395
  3. In theory, 1 g of ricin is enough to kill over 1000 people
  4. J. Kifner, "Man is Arrested in a Case Involving Deadly Poison," New York Times, 23 December 1995
  5. J. Stephenson, "Confronting a Biological Armageddon: Experts Tackle Prospect of Bioterror- ism," JAMA, 7 Aug 1996, Vol. 276, No 5, 349-351
  6. Personal statement by a representative of the US Naval Medical Research Institute (NAMRI) on 29 April 1997
  7. Health Letter of the Centers for Disease Control (CDC) Atlanta, 29 May / 5 June 1995, p. 5
  8. W. Seth Carrus, "Bioterrorism and Biocrimes" - The Illicit Use of Biological Agents in the 20th Century", Center for Counterproliferation Research, National Defense University, August 1998 (March 1999 Rev.) 9. Statement by R. Blitzer, Chief FBI Domestic Terrorism and Counterterrorism Planning Section, In ABC News Prime Time Live show, USA, 25 February 1998, transcript available under
  9. The Lancet, Vol. 353, 9 January 1999, p. 130
  10. United Nations Special Commission
  11. "Medical Management of Biological Casualties," Handbook, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, March 1996
  12. In theory, 1 g of botulinum toxin is enough to kill over 10 million people
  13. Initial studies appeared on the question as to why biological weapons have played only a minor role in the arsenal of terrorists. Cf. R. Purver,"Understanding Past Non-Use of Chemical and Biological Warfare Agents by Terrorists," presentation to the conference on "ChemBio Terrorism: Wave of the Future?" sponsored by the Chemical and Biological Arms Control Institute, Washington, D.C., 29 April 1996
  14. Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on their Destruction of 10 April 1972
  15. Prepared by the Office of Technology Assessment (OTA), 1993, from various sources; US Congress, Office of Technology Assessment, Proliferation of Weapons of Mass Destruction: Assessing of Risks, OTA-ISC-559, Washington, D.C.: US Government Printing Office, August 1993
  16. Cf. R. Preston, "The Bioweaponeers", The New Yorker, 2 March 1998;
  17. Cf. Ken W. Alibek, Stephen Handelman (Contributor), "Biohazard. The Chilling True Story of the Largest Biological Weapons Program in the World - Told From Inside by the Man Who Ran It." Random House Inc., New York 1999
  18. J.P. O'Neill (FBI), statement, Hearing on Terrorist Use of Nuclear/Biological/Chemical Agents, Permanent Subcommittee on Investigation, United States Senate, 1 November 1995
  19. Cf. L.A. Cole, "Clouds of Secrecy: The Army's Germ Warfare Tests over Populated Areas," Totowa, N.J., 1988 and by the same author "The Eleventh Plague: The Politics of Biological and Chemical Warfare," New York, 1997
  20. R. Purver, (endnote 1)
  21. Health Aspects of Chemical and Biological Weapons, WHO, 1970
  22. Information of the Security Council of the United Nations on 25 August 1995 by the Chairman of the United Nations Special Commission (UNSCOM), Ambassador Ekeus
  23. On the basic problems here, see Nilesh Parmar, "It was the plague, or was it?" India Today, 30 November 1994
  24. Cf. T. Sohns "The Proliferation of Weapons of Mass Destruction - A Challenge for Decision Makers" in the ASA Newslatter 99-3, 11 June 1999
  25. Cf. R. Preston, (endnote 17)
  26. J. Matloff, "Danger from Russia's Scientists: Selling Weapons Know -How", The Christian Science Monitor, 13 February 1998;
  27. A survey of the problem of licensing vaccines and other drugs can be found in Steve Sternberg, "Bottle-neck Keeps Existing Vaccines off the Market," Science, No. 266, 7 October 1994; also E.J. Finke, et. al., "List of Vaccines and Immunoglobulins for Prevention of Potential B-Agents", German Armed Forces Medical Academy, Department of Studies and Science, Institute for Microbiology, Munich, manuscript presented at the Third Biological Medical Defense Conference of the German Ministry of Defense, October 1996. According to the revelations of K. Alibekov, formerly the first deputy chief of research and production for the Soviet biological weapons program until his defection to the USA in 1992, "52 biological agents would be used in biological weapons". Alibekov made this statement in ABC News's PrimeTime Live show, USA, 25 February 1998.
  28. J.D. Douglass Jr., "Weapons of Mass Destruction - A Biological Weapons Threat Worse Than Saddam", 10 March 1998;

Table 1. "Dirty Dozen" toxins and diseases.

Bacteria Viruses Toxins
glanders and meliodosis
Q fever
viral encephalitis (e.g., VEE)
viral hemorrhagic fevers(e.g., Marburg)
botulinum toxin
staphylococcal enterotoxin B

Table 2. Motives in Terrorism

Terrorism Category Motivation
State sponsored and controlled political
Groups and sects political or fanatical
Individuals fanatical

Table 3. Proliferation Risks: Suspected Biological Weapons Programs


(policy paper)

(USG officials)


(Def & FA)





Libya + + + + +   5 71
North Korea + + + + +   5 71
Iraq +   + + + + 5 71
Taiwan + + +     + 4 57
Syria + + +     + 4 57
Russia (Soviet Union) +   + +   + 4 57
Israel +   + + +   4 57
Iran + +   + +   4 57
China + + +     + 4 57
Egypt     +   + + 3 43
Vietnam     +       1 14
Laos     +       1 14
Cuba       +     1 14
Bulgaria       +     1 14
India         +   1 14

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