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Biological Agents as Weapons


James M. Madsen

, MD, MPH, University of Florida

Reviewed/Revised Jan 2023
Topic Resources

Biological warfare (BW) is the use of microbiological agents for hostile purposes. Such use is contrary to international law and has rarely taken place during formal warfare in modern history, despite the extensive preparations and stockpiling of biological agents carried out during the 20th century by most major powers (including development of strains resistant to multiple drugs). The area of most concern is the use of BW agents by terrorist groups. Biological-warfare agents are thought by some to be an ideal weapon for terrorists. These agents may be delivered clandestinely, and they have delayed effects, allowing the user to remain undetected.

The US Centers for Disease Control and Prevention (CDC) has prioritized biological agents and toxins into 3 groups: A (highest priority), B, and C (see table CDC High-Priority Biological Agents and Toxins CDC High-Priority Biological Agents and Toxins* CDC High-Priority Biological Agents and Toxins* ).


Recognition of Biological Weapon Injuries

It can be difficult to distinguish use of a biological-warfare (BW) agent from a natural outbreak of disease. Clues to the deliberate rather than a natural origin of a disease outbreak include the following:

  • Cases of diseases not usually seen in the geographic area

  • Unusual distribution of cases among segments of the population

  • Significantly different attack rates between those inside and those outside buildings

  • Separate outbreaks in geographically noncontiguous areas

  • Multiple simultaneous or serial outbreaks of different diseases in the same population

  • Unusual routes of exposure (eg, inhalation)

  • Zoonotic disease occurring in humans rather than in animals

  • Zoonotic disease occurring first in humans and then in its typical vector

  • Zoonotic disease arising in an area with a low prevalence of the typical vector for the disease

  • Unusual severity of disease

  • Unusual strains of infectious agents

  • Failure to respond to standard therapy

Epidemiologic investigation of cases and cooperation with law-enforcement resources are crucial, as is risk communication to the general public.

Isolation (of patients) and quarantine (of contacts) may be necessary. The most communicable deliberately disseminated diseases are smallpox (for which airborne precautions are necessary) and pneumonic plague (necessitating droplet precautions).

Response to Biological Weapon Injuries

Because of the relatively long incubation periods of diseases caused by BW agents, most lives will be saved or lost in a hospital setting. Adequate supplies of vaccines, antibiotics, and antivirals for hospitalized patients and for contacts are needed, and systems for distributing such medical countermeasures to members of the general public at high risk of exposure are crucial.

The views expressed in this article are those of the author and do not reflect the official policy of the Department of Army, Department of Defense, or the US Government.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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