• Knowledgebase: Biological & Chemical Warfare and Terrorism

    Answers to questions about Biological and Chemical terrorism and warfare.

    13. Biological Warfare: From MS Encarta - Top

    Biological warfare agents include bacteria, viruses, fungi, and other living microorganisms that can kill or incapacitate. Since they can reproduce, biological agents have the unique potential to make an environment more dangerous over time. If used for hostile purposes, any disease-causing microorganism could be considered a weapon. For the purposes of warfare, specific characteristics of certain agents make them more likely to be used than others.

    Some potential warfare agents can make their victims very sick without necessarily killing them. Examples include the microorganisms that cause tularemia, Q fever, and yellow fever. After suffering debilitating illness, victims of these diseases often recover, although not always. Other agents are more likely to be lethal. The bacteria that cause bubonic plague and the virus that causes smallpox can kill large numbers of untreated people. Early antibiotic treatment usually cures plague victims, and smallpox vaccinations before exposure to the virus can prevent the disease.

    Anthrax bacteria are considered likely weapons because of their particular features. They can exist as hardy, shell-like forms called spores. In a warm, moist environment like the human lung, the spores can become active and highly lethal. Anthrax bacteria are usually found under the soil surface, and cause disease primarily in cattle and other grazing livestock. But if released into the air and inhaled, a few thousand spores can be fatal.

    Botulinum toxin is also lethal in tiny doses. Although often categorized as a biological weapon, the toxin is not itself a living agent, but a product of the bacterium Clostridium botulinum. The toxin is dangerous whether inhaled or ingested in food or drink. A gallon of botulinum toxin could poison a small city's water system, but existing water purification systems can neutralize the toxin and protect city dwellers. See also Botulism.


    Biological Warfare History

    The use of biological weapons has been more rare than the use of chemical weapons. In the 14th century, plague-infected cadavers purportedly were catapulted into an enemy camp in the Russian Crimea. In colonial America, the British delivered blankets from their smallpox infirmary to Native Americans, hoping to infect them with the disease. In the 20th century, the only extensive military biological attacks were by Japan against China in the late 1930s and 1940s. The Japanese dropped plague and other bacteria from airplanes over several towns, causing outbreaks of disease. The only large-scale terrorist attack with a biological weapon occurred in 1984 in the United States. Members of the Rajneesh cult in Oregon placed salmonella bacteria in the salad bars of several restaurants. Although 750 people became ill, none died.


    Delivery Systems

    Chemical and biological agents are most effective when dispersed into the air. These agents are often fitted into bombs or artillery shells that are designed to explode in the air and spread their contents over an enemy. In the 1980s, the United States began to deploy binary chemical weapons. Older chemical shells and bombs housed a single blistering or nerve agent. As they aged, these weapons could leak their poisons. A binary weapon is safer because it contains two relatively harmless chemicals. Only after firing do the chemicals combine to form a potent mix.

    In some warfare or terrorist scenarios, an explosive release is not necessary. Members of Aum Shinrikyo attacked the Tokyo subway by packing sarin in plastic containers. To release the nerve agent, they pierced the containers with sharp umbrella tips. The leaking liquid and vapor affected thousands of passengers.

    Microorganisms are generally more fragile than chemicals, and some might not survive an explosion. But several, like anthrax spores, do remain potent after an explosive release. In any case, United States Army tests have shown that biological agents can be broadly dispersed in a variety of non-explosive ways. In the 1950s and 1960s the Army released bacteria and chemical particles in hundreds of tests in populated areas throughout the country. Agents were sprayed at San Francisco from a boat offshore, dispensed from slow-moving cars in Minneapolis and St. Louis, and released from light bulbs dropped in the New York subway. The bacteria and chemicals in the tests were not as dangerous as actual warfare agents, although they posed some risks to the exposed populations. They demonstrated that an enemy or terrorist could expose millions of people to disease-causing organisms by a variety of simple techniques.

    - Updated: October 22, 2001

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    • James L Horwitz, MD

    David C. Thomas, MD

    Barbara Lindberg, PNP