Bioterrorism is use of infectious agents or other harmful biological or biochemical substances i.e. from biological source as weapons of terrorism. It is intentional release or dissemination of biological agents. These agents are bacteria, viruses, fungi, or toxins, and may be in a naturally occurring or a human-modified form.

Bioterrorism refers to biological agents (microbes or toxins) used as weapons to further personal or political agendas. Acts of bioterrorism range from a single exposure directed at an individual by another individual to government-sponsored biological warfare resulting in mass casualties.


Bioterrorism differs from other methods of terrorism in that materials needed to make an effective biological agent are readily available, require little specialized knowledge and are inexpensive to produce. An attack may be difficult to distinguish from a naturally occurring infectious disease outbreak.




This is 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 sometimes that they could be changed to increase their ability to cause disease (increased virulence to cause disease), make them resistant to current medicines, or with increased ability to be spread into environment.


There are three basic groups of biological agents that could likely be used as weapons: bacteria, viruses and toxins. Biological agents can be dispersed by spraying them into the air, person-to-person contact, infecting animals that carry the disease to humans and by contaminating food and water. They may be used as they can be extremely difficult to detect and do not cause illness for several hours to several days.

The bioterrorism agents of greatest concern are anthrax (bacterium) and smallpox (virus). Both can be lethal. Anthrax is not communicable while smallpox is readily transmitted from person to person. In humans, the three forms of anthrax are inhalational, cutaneous and intestinal.


Bioterrorism agents can be separated into three categories, depending on how easily they can be spread and the severity of illness or death they cause. Category A agents are considered the highest risk and Category C agents are those that are considered emerging threats for disease.




Category A

These are high-priority agents which include organisms or toxins that pose the highest risk to the public and national security. E.g. Smallpox, Anthrax, Tularemia, Bubonic plague, Botulinum Toxin etc. They pose greatest risk because they:

  • Can be easily spread or transmitted from person to person.
  • Result in high death rates and have the potential for major public health impact.
  • Might cause public panic and social disruption.
  • Require special action for public health preparedness.


Category B

These are agents of second highest priority with lower/moderate risks and severity than the agents of Category A. E.g. Brucella, Epsilon Toxin, Staphylococcal enterotoxin etc. Agents of these category:

  • Moderately easy to spread.
  • Result in moderate illness rates and low death rates.
  • Require specific enhancements of CDC’s laboratory capacity and enhanced disease monitoring.


Category C

These includes agents of third highest priority or lowest priority among bioterrorism agents. It includes emerging pathogens that could be engineered for mass spread in the future such as Nipah virus, Hanta virus, SARS, HIV/AIDS etc.

Agents of category can be used as bioterrorism agents as:

  • Easily available.
  • Easily produced and disseminated.
  • Have potential for high morbidity and mortality rates and major health impact.


Protection against bioterrorism (Biosecurity) can be:

  • Physical protection: Gas mask
  • Immunological protection: Mass Vaccination


Download Link: Bioterrorism and Bio-Agents.pdf

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