During the past two decades, the potential use of biological weapons by terrorists has received a great deal of attention, particularly in the United States. The existence of an anthrax bioweapons development campaign by the government of Iraq was revealed during the Persian Gulf War from 1990 to 1991. Then, in the aftermath of the September 11, 2001 terrorist attacks on the World Trade Center buildings in New York City and the Pentagon in Washington, DC., letters containing a powdered form of Bacillus anthracis, the bacteria that causes anthrax, were mailed to government representatives, members of the news media, and others in the United States. The anthrax-laced powder inside the letters was aerosolized (i.e., the spores became airborne) when the letters were opened, and in a few cases were inhaled. The death of a Florida man was the first case of an inhalational anthrax death in the United States since 1978 and as of June 2002, more than 20 cases and five deaths were attributed to the terrorist attack.
Although a relatively new weapon in the hands of modern potential bioterrorists, the threat of death from the inhalation of anthrax has been part of human history since antiquity. Some scholars argue that it is the sooty "morain" in the Bible's Book of Exodus, and is likely the "burning wind of plague" that begins Homer's Iliad.
As well, the use of microorganisms such as the anthrax bacteria as weapons is not new. In ancient military campaigns, diseased bodies (including those who died of anthrax) were used to poison wells and were catapulted into cities under siege. Research into the military use of anthrax was carried out during World War I by combatants on all sides of the conflict, and by World War II anthrax research was actively underway. For example, Allied efforts in Canada, the United States, and Britain to develop anthrax-based weapons included the production of five million anthrax "cakes," designed to be dropped on Germany to infect wells and the food chain. The weapons were never used.
Only within the past several decades, however, have biological weapons, including anthrax, been added to the arsenal of terrorists. For example, the Japanese cult Aum Shinrikyo (which released sarin gas into the Tokyo subway system in 1995, killing 12 people and hospitalizing 5,000) was developing anthrax-based weapons. Indeed, the group had released crude anthrax preparations in Tokyo on at least eight separate occasions in 1993. These incidents were the first time that anthrax was used as a weapon against a civilian population. In addition, state-sanctioned terrorism by the government of Iraq has also, purportedly, involved the production of anthrax bioweapons, and Western intelligence sources insist that Iraqr terrorist groups operating with Iraq's assistanceontinues (despite United Nations' efforts at inspection and destruction) to develop biological weapons, including anthrax-based weapons. Finally, during the terrorist attacks of the United States in the latter part of 2001 the use of anthrax by a terrorist or terrorists (as of June 2002, yet unidentified) pointed out how easily the lethal agent could be delivered.
This ease of delivery of anthrax is one feature that has made the bacterium an attractive weapon for terrorists. Scenarios developed by United States government agencies have shown that even a small crop dusting plane carrying only a hundred kilograms of anthrax spores flying over a city could deliver a potentially fatal dose to up to three million people in only a few hours. Although variations in weather patterns and concentration variables would substantially reduce the number of expected actual deaths, such an attack could still result in the deaths of thousands of victims and result in a devastating attack on the medical and economic infrastructure of the city attacked. In a less sophisticated effort, spores could simply be released into air intake vents or left in places like a subway tunnel, to be dispersed in the air over a much small area.
Another feature of anthrax that has led to its exploitation by terrorists is the physiology of the bacterium. Bacillus anthracis can live as a vegetative cell, growing and dividing in a rapid and cyclical fashion. The bacterium can also form a metabolically near-dormant form known as a spore. An individual spore is much smaller and lighter than the growing bacterium. Indeed, the spores can drift on air currents, to be inhaled into the lungs. Once in the lungs, the spores can resuscitate into an actively growing and dividing bacterium. The infections that are collectively termed anthrax can result. Although millions of spores can be released from a few grams (fractions of an ounce) of Bacillus anthracis, only about 5,000 to 8,000 spores are sufficient to cause the lung infection when they are inhaled. If left untreated or not promptly treated with the proper antibiotics (e.g., Cipro), the lung infection is almost always fatal. Non-inhalation contact with Bacillus anthracis can result in cutaneous anthrax condition more treatable with conventional antibiotic therapy.
An often-overlooked aspect of the use of anthrax as a terrorist weapon is the economic hardship that the dispersal of a small amount of the spores would exact. A report from the Centers for Disease Control and Prevention, entitled The Economic Impact of a Bioterrorist Attack, estimated the costs of dealing with an anthrax incident at a minimum of US$26 billion per 100,000 people. In just a few months in 2001 alone, a flurry of anthrax incidents, most of which turned out to be hoaxes, cost the United States government millions of dollars.
The choice of anthrax as a weapon by terrorists reflects the growing awareness of the power of biological research and biotechnology among the general community. The ability to grow and disperse infectious microorganisms was once restricted to specialists. However, the explosion of biotechnology in the 1980s and 1990s demonstrated that the many basic microbiological techniques are fairly simple and attainable. Experts in microbiology testifying before Congress, estimated that crude weapons could be developed with approximately $10,000 worth of equipment. A laboratory sufficient to grow and harvest the bacteria and to dry down the material to powdered form could fit into the average sized household basement.
Even though Bacillus anthracis could be grown in such a makeshift laboratory, the preparation of the spores and the drying of the spores into a powder is not a trivial task. As an example, even after a decade of dedicated effort, United Nations inspectors who toured Iraq bioweapons facilities after the Gulf War found that Iraq had only managed to develop crude anthrax preparations. Still, the Iraq bioweapons program managed to produce 8,500 liters of concentrated anthrax.
Regardless, despite the technical challenges, the production of anthrax spores in quantities great enough to cause a huge loss of life is not beyond the capability of a small group of equipped and funded terrorists. This small size and nondescript nature of a bioweapons facility could make detection of such a lab very difficult. Accordingly, the terrorist potential of anthrax will remain a threat for the foreseeable future.
See also Bacteria and bacterial infection; Biological warfare; Bioterrorism, protective measures; Bioterrorism; Epidemics and pandemics; Vaccine
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