It happened in 1988
Poison gas and other chemical weapons have usually involved troops in battle. However, in 1988 the Iraqi military, under President Saddam Hussein, dropped canisters of gas on the Iraqi Kurdish population in many different locations. The exact ingredients in the chemical cocktail used are not known.

Unleashing silent killers: diseases
These gas attacks on the Kurds were outright attempts at repression, perhaps even genocide. But what if a government or terrorist organization wanted to unleash a silent killer, something that would be difficult to trace and would generate fear and panic in the targeted people? One way to accomplish this would be through the use of deadly infectious diseases. These "biologic weapons" are inexpensive, and some are easy to obtain, produce, deliver, and conceal.

Anthrax
Perhaps the disease most discussed in the media, anthrax usually affects sheep, cattle, and other livestock. The organism is found in soil around the world. Its spores are resistant to sunlight, disinfectants, and temperature extremes. Anthrax can be transmitted through the skin (the usual, accidental way), by ingesting it, and by inhaling it (the way it would most likely be purposely transmitted). Anthrax infection can be treated with antibiotics, but once symptoms occur more than 80% of its victims die from hemorrhaging in their lungs and from meningitis (brain infection). It is not spread from person to person.

The scenario: Anthrax spores in powdered form sprayed into the air. (Investigators in the United States believe that in October 2001 when anthrax-infected mail passed through automatic mail sorting machines anthrax spores were dispersed into the air. This allowed it to be inhaled.)

The Plague
No, the plague didn't end in the Middle Ages. It lives in Africa and Asia, and is transmitted either from the bites of infected fleas (bubonic form) or from exposure to infected people's coughing and sneezing (pneumonic form). The pneumonic form is the one most likely to be purposely transmitted. Untreated pneumonic plague is fatal, but even with treatment, about 50% of its victims die from pneumonia. It is easily spread from person to person.

The scenario: Plague bacteria sprayed in the air; once infected, people spread it to other people around them.

Tularemia
This bacteria is transmitted to humans from infected rabbits and other small animals through their fleas, or by direct contact. It produces either lymph node disease with skin ulcers, or typhoid-like symptoms with pneumonia (the most likely to occur with purposeful infection). Since it can look like typhoid fever or pneumonia, it would likely be missed as a possible diagnosis. It can be treated with antibiotics; untreated, about 35% of its victims die of pneumonia or kidney failure.

The scenario: Tularemia bacteria is spread by direct contact with an object that has the bacteria on it.

Smallpox
This disease, once a worldwide scourge, no longer occurs naturally. However, since people are no longer vaccinated against it, most people may have no immunity to the virus that causes it. The virus is extremely infectious and easily spread from person to person by coughing and sneezing, and from touching the skin lesions that develop. It is not known how lethal smallpox would be today, but estimates are that about 30% of nonimmunized victims, and about 3% of immunized victims, would die of overwhelming infection or hemorrhages. Treatment is by vaccination within a few days of exposure, or the use of immune globulin.

The scenario: Smallpox virus is sprayed in the air, and once infected, people spread it to others around them. A similar virus, monkeypox, might be used, and either virus could be genetically modified to be resistant to vaccination.

Botulinum toxin
Botulinum toxin (from Clostridia bacteria which causes botulism) is one of the most poisonous substances known. The toxin is absorbed into the body through a wound or by eating contaminated food. Botulism poisoning causes muscle paralysis.

The scenario: Botulinum toxin sprayed in the air or put into food.

Viral hemorrhagic fevers
Viruses in this group cause fever and bleeding disorder (hemorrhage). The infected person becomes extremely ill and may bleed to death. The best known virus is Ebola, but there are several others that are just as deadly, and there is no cure for any of them.

The scenario: Infected droplets sprayed into the air, and once infected, people spread it to others around them. Contact with contaminated items can also spread the viruses.

This is just a brief look at the possibilities of using rare diseases as biological weapons. If you would like to explore the topic further, try the Johns Hopkins Center For Civilian Biodefense Strategies.

Information for this article was taken from:
- Olson, J. E., and Relman, D. A. (2000). Biologic weapons: What infectious disease practitioners need to know. Infect Med, vol. 17, no. 1, 29-44.
- Strobel, Warren P. Saddam's lingering atrocity. U.S. News & World Report, November 27, 2000.

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