The intentional use of biological pathogens to kill or incapacitate one’s enemies has occurred sporadically for centuries. One of the earliest documented cases occurred at the Crimean port city of Kaffa (now Feodosia, Ukraine) in 1346. Besieging Tatar armies were stricken with bubonic plague and decided to turn this unfortunate incident to their advantage by catapulting plague-rid den corpses into the city (Derbes, 1966).
Genoese defenders within the city walls subsequently contracted plague and fled to Italy, thus carrying the disease to Europe. The resulting epidemics culminated in what we now know as the Black Death, which wiped out nearly one-third of the European population in the Middle Ages. Until recently, concern over biological weapons focused mainly on their use by an adversary on the battlefield. Several events, however, have heightened concerns that these agents could be employed by terrorists.
As many as 18 countries currently are suspected of having biological-weapons research and development programs (Siegrist, 1999). Of the seven countries listed by the State Department as sponsors of international terrorism, at least five are known or suspected to have bio-weapons programs. Most notably, before the Gulf war, intelligence sources suspected that the Iraqis had a biological weapons program. In 1995, the Iraqis admitted to having weaponized anthrax, botulinum toxin, and aflatoxin (Zilinskas, 1997).
Revelations by defectors from the biological weapons program of the former Soviet Union revealed the massive extent of that program, including the industrial capacity to produce tons of biological agents, such as anthrax and smallpox, each year. The Soviets used the signing of the Biological Weapons Convention in 1972 as a launching point for accelerating their program. Moreover, they also saw the global eradication of smallpox and the subsequent discontinuation of vaccination against the disease as an opportunity to exploit smallpox as a weapon.
Since the breakup of the Soviet Union, there has been concern that many of the scientists put out of work by the deteriorating economies of former Soviet states could take their expertise to a country developing a biological warfare program. (Alibek and Handelman, 1999) A wake-up call came with the 1995 sarin nerve agent attack in the Tokyo subway system by the terrorist organization Aum Shinrikyo. This event demonstrated that terrorist organizations had acquired the ability to use unconventional weapons.
It was later revealed that the cult had used sarin once previously in Matsumoto, Japan, in 1994, and had made several attempts to release the biological agents anthrax and botulinum toxin. Given that a terrorist organization could choose to use conventional, chemical, or nuclear weapons, why might it resort to a bioagent? There are several reasons, which, when considered as a whole, might point to biological weapons as the ultimate terrorist weapons. First, the agents themselves are relatively easy to procure.
Organisms such as Clostridium botulinum, the agent that produces botulinum toxin, and hence botulism, is ubiquitous in soil. Other organisms, such as Bacillus anthracis, the causative agent of anthrax, and Yersinia pestis, the causative agent of plague, could be collected from areas around the globe where the diseases are endemic–either from the soil (anthrax) or from diseased animals (anthrax and plague). Moreover, numerous legitimate laboratory supply houses around the world sell many agents that might be adapted for use as weapons.
A terrorist conceivably could obtain pathogens by illegitimate means from these supply houses or from research laboratories. Second, a 1969 United Nations expert panel concluded that the relative cost to produce mass casualties over 1 square kilometer was $600 for a chemical weapon, $800 for a nuclear weapon, $2,000 for a conventional weapon, and only $1 for a biological weapon (NATO Handbook). Furthermore, to produce biological weapons, one might employ the same fermentation technology that is commonly used in the production of legitimate products such as antibiotics, vaccines, wine, and beer.
This circumstance makes biological-weapons production relatively easy to conceal and makes compliance with existing weapons conventions difficult to verify. An important feature distinguishing bio-weapons from other weapons is the incubation period characteristic of each biological agent. This period ranges from hours to weeks, but is generally on the order of days. A perpetrator could thus release an agent and be out of the country by the time the effects are recognized. There are three general routes by which a bio-weapon may produce infection: percutaneous, oral, and inhalation.
Unlike with chemical agents, which are dermally active, intact skin provides an impermeable barrier to most biological weapons, with the exception of T2 mycotoxins. Therefore, to infect someone, a microorganism must enter through a break in the skin. A second route of infection involves oral intake of contaminated food or water. This route was demonstrated in 1984 when the Rajneeshee cult infected local salad bars in Dalles, Oregon, with Salmonella typhimurium in an attempt to influence the outcome of local elections.
At least 751 cases of salmonellosis resulted (Torok et al, 1997). The third possible route of exposure is through inhalation. This route has the greatest potential to cause mass casualties. Unfortunately, use, threat of use, interest in use, interest in acquisition, and actual acquisition have all increased notably during the decade of the 1990s. Several factors likely account for this, including the widespread knowledge provided in lay publications and on the Internet, and the attention that this issue has garnered in the media.
Although most cases of use have involved small-scale biocrimes, the ability clearly exists to acquire and produce these agents. Working groups from the Johns Hopkins Center for Civilian Biodefense and the Centers for Disease Control and Prevention (CDC) recently convened to consider diseases that might cause a maximum credible event (defined as an event with the potential to cause large loss of life, panic, and overwhelming of health care resources) and for which specific and intense planning are needed to handle the consequences of a release on a large population.
Such agents include smallpox, anthrax, plague, tularemia, botulinum toxin, and viral hemorrhagic fevers. A number of defensive measures have been taken to prevent a maximum credible event from occurring. Recent laws passed by Congress impose criminal penalties for the possession, manufacture, or use of biological weapons and give law enforcement agencies the right to seize potential agents or delivery devices (Ferguson, 1997).
Intelligence agencies and law enforcement personnel are developing sophisticated systems to monitor potential terrorists and to learn what they might use, and when they might use it. Unlike chemical agents, most biological agents can be effectively removed from human skin with soap and water. Biological agents are nonvolatile and relatively difficult to re-aerosolize, so even without specific decontamination, secondary exposure would be unlikely.
This is in contrast to the circumstances associated with chemical agents, in which victims generally present immediately after an attack and may still have volatile agent on their bodies or clothes, putting the care provider and hospital environment at risk of contamination and secondary exposure. With biological agents, detection is more difficult than with chemical agents. Various organizations are currently developing technologies to improve the speed and accuracy of methods for detecting and diagnosing biological agents.
Finally, it is important for health care providers to become more aware of the threat of bioterrorism and how they will manage should a release occur. Education is one of the cornerstones of our defense. Through forums such as NEHA’s annual educational conference, the U. S. Army Medical Research Institute of Infectious Diseases (USAMRIID) annual satellite broadcast on the medical defense against biological weapons, and other military and nonmilitary educational efforts, more health care providers will, it is hoped, maintain a heightened awareness and an appropriate level of concern.
References: Alibek, K. and S. Handelman (1999), Biohazard, New York: Random House. Derbes, V. J. (1966), “DeMussis and the Great Plague of 1348, a Forgotten Episode of Bacteriological Warfare”, Journal of the American Medical Association, 196(1):59-62. Ferguson, J. R. (1997), “Biological Weapons and the Law,” Journal of the American Medical Association, 278(5):357-360. NATO Handbook on the Medical Aspects of NBC Defensive Operations: AmedP-6(B) (1996), Washington, D. C.
: Departments of the Army, Navy, and Air Force. Siegrist, D. W. (1999), “The Threat of Biological Attack: Why Concern Now? ” Emerging Infectious Diseases, 5(4):505-508. Torok, T. J. , et al. (1997), “A Large Community Outbreak of Salmonellosis Caused by Intentional Contamination of Restaurant Salad Bars,” Journal of the American Medical Association, 278(5):389-395. Zilinskas, R. A. (1997), “Iraq’s Biological Weapons: The Past as Future? ” Journal of the American Medical Association, 278(5):418-424.