Bioterrorism is terrorism by intentional release or dissemination of biological agents (bacteria, viruses or toxins); these may be in a naturally-occurring or in a human-modified form.


According to the U.S. Centers for Disease Control and Prevention (CDC):

A bioterrorism attack is the deliberate release of viruses, bacteria, or other germs (agents) used to cause illness or death in people, animals, or plants. These agents are typically found in nature, but it is possible that they could be changed to increase their ability to cause disease, make them resistant to current medicines, or to increase their ability to be spread into the environment. Biological agents can be spread through the air, through water, or in food. Terrorists may use biological agents because they can be extremely difficult to detect and do not cause illness for several hours to several days. Some bioterrorism agents, like the smallpox virus, can be spread from person to person and some, like anthrax, can not.


Biological terrorism dates as far back as ancient Roman civilization, where dead and rotting animals were thrown into wells to poison water supplies. (Bock,2001) This early version of biological terrorism was used to destroy enemy forces covertly. It continued on into the 14th century where the bubonic plague was used to infiltrate enemy cities by both instilling the fear of infection in residences, in hopes that they would evacuate, and also to destroy defending forces that would not yield to the attack. The use of disease as a weapon in this stage of history exhibited a lack of control aggressors had over their own biological weapon. Primitive medical technology provided limited means of protection for the aggressor and a battles surrounding geographical regions. After the battle was won, the inability to contain enemies who escaped death lead to wide spread epidemics affecting not only the enemy forces, but also surrounding regions inhabitants. Due to the use of these biological weapons, and the apparent lack of medical advancement necessary to defend surrounding regions from them, wide spread epidemics such as the bubonic plague quickly moved across all of Western Europe, destroying a large portion of its population. The victims of biological terrorism in fact became weapons themselves. This was noted in the Middle Ages, but medical advancements had not progressed far enough to prevent the consequences of a weapons use. (Eitzen and Takafuji, 1997)

In the 15th century, smallpox was used on contaminated clothing to defeat South American and Native American forces. (Bock, 2001) Again, the use of biological weapons for which limited protection and containment was available, lead to casualties on both sides of battles. Bioterrorism continued to be an effective method of weakening an adversary but it was also difficult to contain. In the Revolutionary War, colonists were vaccinated from the small-pox virus and then used the virus to intentionally infect enemies. This demonstrates a major advancement in the evolution of bioterrorism. Once the ability to defend from biological warfare became possible through medical advancement, the weapons became far more valuable.

As time continued the use of biological warfare became more and more sophisticated. Countries were developing weapons that delivered much higher effectiveness and less chance of infecting the wrong party. One significant enhancement in biological weapon development was the first use of Anthrax. Anthrax effectiveness was initially limited to victims of large dosages. This became a weapon of choice because it is easily transferred, has a high mortality rate, and can be easily obtained. Also, variants of the Anthrax bacterium can be found all around the world making it the biological weapon of choice in the early 19th century. Another property of Anthrax that helped fuel its use as a biological weapon is its poor ability to spread far beyond the targeted population.

By the time World War I began, attempts to use anthrax were directed at animal populations. This was ineffective. Instead, the use of poisonous mustard gas became the biological weapon of choice. The sheer horror of its affects lead to a treaty called the Geneva Protocol of 1925. The treaty was created to prevent the use of asphyxiating gas as a method of biological warfare. (Brooks, 2001) While this was a significant advancement toward the prevention of biological weapon use, the treaty said nothing about weapon development. Secretly, biological weapon development programs existed in many nations. While no documented instances of biological weapon use exist it is believed that this was primarily due to the programs immaturity and not the unwillingness to use them.

American biological weapon development began in 1942. President Franklin D. Roosevelt placed George W. Merck in charge of the effort to create a development program. You may recognize the name Merck, Mr. Merck is also the founder of Merck Pharmaceuticals. These programs continued until 1969, when by executive order President Richard Nixon shut down all programs related to American offensive use of biological weapons. (

Accusations of the use of biological weapons against North Korea were spread during Viet Nam, however it is believed that those accusations were propaganda developed by the North Korean regime to villainize American Armed Forces. As the 70’s passed, global efforts to prevent the development of biological weapons and their use were widespread. In 1972 the prohibition of development, production and stockpiling biological weapons was developed.

In the 1980’s Iraq made substantial efforts to develop and stockpile large amounts of biological weapons. By the end of the 80’s Iraq had several sites dedicated to the research and development of biological warfare. They began to test their findings in the late 80’s. These actions lead to the first Gulf war in which Iraq’s biological weapons were dismantled and destroyed.

Since that time, efforts to use biological warfare has been more apparent in small radical organizations attempting to create fear in the eyes of large groups. Some efforts have been partially effective in creating fear, due to the lack of visibility associated with modern biological weapon use by small organizations. In 1995 a small terrorist group launched a terrorist attack aboard a Tokyo subway. The attack killed twelve and affected more than 5000. The response of Japanese emergency services successfully prevented an outcome with much higher mortality rates.

In the United States a more recent biological terrorism attack occurred in 2001 when letters laced with infectious anthrax were delivered to news media offices and the U.S Congress. (Johnston,2005) The letters killed 5. While many believed this attack to be in relation to Iraq’s development of biological weapons, tests on the anthrax strand used in the attack pointed to a domestic source.

Types of biological agents

The CDC has defined and categorized bioterrorism agents according to priority 2 as follows:

Category A agents

These are biological agents with both a high potential for adverse public health impact and that also have a serious potential for large-scale dissemination. The Category A agents are anthrax, smallpox, plague, botulism, tularemia, and viral hemorrhagic fevers.

Anthrax is a non-contagious disease. An anthrax vaccine does exist but requires many injections and has side effects that render it unsuitable for general use.

Smallpox is a highly contagious virus. It transmits easily through the atmosphere and has a high mortality rate (20-40%). Smallpox was eliminated in the world in the 1970s, thanks to a worldwide vaccination program. However, some virus samples are still available in Russian and American laboratories. Some believe that after the collapse of the Soviet Union, cultures of smallpox have become available in other countries. Although people born pre-1970 will have been vaccinated for smallpox under the WHO program, the effectiveness of vaccination is limited since the vaccine provides high level of immunity for only 3 to 5 years. As a biological weapon smallpox is dangerous because of the highly contagious nature of both the infected and their pox. Smallpox occurs only in humans, and has no external hosts or vectors.

Botulinum toxin
Botulinum toxin is one of the deadliest toxins known, and is produced by the bacterium Clostridium botulinum. Botulism causes death by respiratory failure and paralysis. It is also easy to obtain since it is found in the cosmetic products Botox and Dysport.

Ebola is a viral hemorrhagic fever, with fatality rates ranging from 50-90%. No cure currently exists, although vaccines are in development. The United States and the erstwhile Soviet Union both investigated the use of ebola for biological warfare, and the Aum Shinrikyo group possessed cultures of the virus. Ebola kills its victims through multiple organ failure and hypovolemic shock.

Plague is a disease caused by the Yersinia pestis bacterium. Rodents are the normal host of plague, and the disease is transmitted to humans by flea bites and occasionally by aerosol in the form of pneumonic plague. The disease has a history of use in biological warfare dating back many centuries, and is considered a threat due to its ease of culture and ability to remain in circulation among local rodents for a long period of time.

Marburg is a viral hemorrhagic fever virus first discovered in Marburg, Germany. Fatality rates range from 25-100%, and although a vaccine is in development, no treatments currently exist aside from supportive care. As with ebola, basic barrier nursing significantly reduces the virulence of the virus.

Tularemia, or rabbit fever, is a generally non-lethal and severely incapacitating disease caused by the Francisella tularensis bacterium. It has been widely produced for biological warfare due to its highly infective nature, and ease of aerosolization.

Category B agents

Category B agents are moderately easy to disseminate and have low mortality rates.

Brucellosis (Brucella species) Brucellosis is an infectious disease caused by the bacteria of the genus Brucella. These bacteria are primarily passed among animals, and they cause disease in many different vertebrates. Various Brucella species affect sheep, goats, cattle, deer, elk, pigs, dogs, and several other animals. Humans become infected by coming in contact with animals or animal products that are contaminated with these bacteria. In humans brucellosis can cause a range of symptoms that are similar to the flu and may include fever, sweats, headaches, back pains, and physical weakness. Severe infections of the central nervous systems or lining of the heart may occur. Brucellosis can also cause long-lasting or chronic symptoms that include recurrent fevers, joint pain, and fatigue

  • Epsilon toxin of Clostridium perfringens
  • Food safety threats (e.g., Salmonella species, E coli O157:H7, Shigella, Stash)
  • Glanders (Burkholderia mallei)
  • Melioidosis (Burkholderia pseudomallei)
  • Psittacosis (Chlamydia psittaci)
  • Q fever (Coxiella burnetii)
  • Ricin toxin from Ricinus communis (castor beans)
  • Staphylococcal enterotoxin B
  • Typhus (Rickettsia prowazekii)
  • Viral encephalitis (alphaviruses, e.g.: Venezuelan equine encephalitis, eastern equine encephalitis, western equine encephalitis)
  • Water supply threats (e.g., Vibrio cholerae, Cryptosporidium parvum, Cholera )

Category C agents

Category C agents are pathogens that might be engineered for mass dissemination because they are easy to produce and have potential for high morbidity or mortality (examples: nipah virus, hantavirus and multi-drug resistant Tuberculosis (MTB).

Bioterrorism on Wikipedia

For more information about Bioterrorism please visit Bioterrorism on Wikipedia.