• Also Known As:
  • Biological Warfare
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What are bioterrorism agents?

Bioterrorism agents are organisms that are deliberately used to sicken and kill. They include bacteria, viruses, and fungi, as well as their toxic byproducts. Terrorists may use these agents due to the deep psychological impact on the fearful public. Many consider them to be a poor man’s atomic bomb as they can be cheap to manufacture, easy to distribute, and are difficult to detect.

Bioterrorism agents can be carried in food products, dispersed into the air or drinking water, introduced into crops and livestock, or even sent through the mail as exemplified by the 2001 anthrax letters. Their use has been internationally condemned by 183 countries through the Biological Weapons Convention treaty.

Most potential bioterrorism agents are natural substances or microorganisms that normally cause a few deaths each year and/or make the news during periodic outbreaks. This was recently seen with Ebola virus in Africa and Eastern equine encephalitis virus in the U.S. These agents can enter the body by being inhaled into the lungs, ingested, through breaks in the skin, or through contact with the mucous membranes of the eyes and nose.

Agents may be genetically altered by those seeking to use them as a weapon. They can potentially be made more infectious, easier to disperse (i.e., aerosolized) and/or made more resistant to current medical treatments. Some agents cause infections that can be passed easily from person-to-person and these would need to be quickly contained, while others, like anthrax, typically affect only the person exposed but can be deadly without prompt treatment.

History of bioterrorism agents
Bioterrorism agents are considered weapons of mass destruction (WMD) and they have been used in war for thousands of years. This has included dipping arrows into toxins and intentionally poisoning food and water supplies. There are documented cases in the 14th century when dead victims of plague were catapulted over besieged defender’s walls to spread disease. These weapons were heavily researched in World War II at the notorious Japanese Unit 731 and during the Cold War. The Soviet Union had an expansive secret research and development program.


About Bioterrorism


The U.S. Centers for Disease Control and Prevention (CDC) has identified over 65 different potential bioterrorism agents based on the risk level they pose to the public. The table below lists primary examples of select agents and toxins. For more information, see the CDC’s Select Agents and Toxins List.

Disease Agent Agent Type
Anthrax Bacillus anthracis Bacteria
Botulism Clostridium botulinum Bacterial toxin
Plague, Pneumonic Yersinia pestis Bacteria
Smallpox Variola major Virus
Tularemia Francisella tularensis Bacteria
Viral Hemorrhagic Fevers Arenaviruses (Lassa, Machupo)
Bunyaviruses (Congo-Crimean, Rift Valley)
Filoviruses (Ebola, Marburg)
Avian Flu Influenza

Influenza 1918 pandemic


Recombinant virus

Brucellosis Brucella species Bacteria
Q-Fever Coxiella burnetii Bacteria
Typhus Rickettsia prowazekii Bacteria
Glanders Burkholderia mallei Bacteria
SARS SARS-associated coronavirus Virus
Ricin Ricinus communis (castor bean) Plant toxin
Viral Encephalitis Eastern equine encephalitis
Western equine encephalitis
Venezuelan equine encephalitis

For information on the U.S. government emergency preparedness plans if a bioterrorist attack occurred, please visit the CDC’s webpage on Laboratory Response Network for Biological Threats (LRN-B).


In general, there are no readily available tests to screen asymptomatic individuals who may have been exposed to a bioterrorism agent. For those who are showing signs and symptoms, there are rapid molecular assays available to detect the bacterial and viral agents as well as immunoassays to detect toxins.

Most laboratories are not equipped to test for bioterrorism agents. In 1999, the CDC, with its founding partners the Federal Bureau of Investigation and the Association of Public Health Laboratories, established the Laboratory Response Network (LRN). This is an integrated national and international group of clinical, public health, environmental, food, water, veterinary, military, and agriculture laboratories that can respond quickly to bioterrorism, chemical terrorism, and other public health threats.

The network includes over ten thousand clinical sentinel laboratories that can perform some routine preliminary testing to rule out bioterrorism agents and refer presumptive agents to one or more of the 130 designated regional reference laboratories. These regional reference laboratories then conduct confirmation testing to unequivocally identify the results referred to them by the sentinel labs. Regional labs also handle environmental samples (i.e., powders, dust, soil and water) determined to be credible threats by the law enforcement and/or public health communities. At the national level, there are specialized laboratories that are properly equipped, staffed and engineered to grow these highly infectious biological agents and identify specific agent strains. These national labs also provide standardized reagents, protocols, training, and a secure electronic communications system to the LRN laboratories.

Today, the U.S. government as well as the research community and industry are working together to develop quick and effective methods to protect the public against agents like Bacillus anthracis (the cause of anthrax) that could be used in a bioterrorist attack. Research is being focused on developing and/or improving vaccines as an effective public health protective measure.

Laboratories are better prepared than ever before to respond quickly to bioterrorism with the appropriate tests to identify the causes of illnesses while coordinating with health departments, law enforcement, the military and the CDC so that containment and rapid treatment can follow.

View Sources

Sources Used in Current Review

2020 Review completed by Peter Platteborze, PhD, DABCC, FAACC.

Dembek ZF. Ed. Medical aspects of biological warfare, Textbooks of military medicine, 2007, Washington, DC: Borden Institute.

(September 10, 2020) Select Agents and Toxins List. CDC Federal Select Agent Program [On-line information]. Available online at https://www.selectagents.gov/sat/list.htm?CDC_AA_refVal=https%3A%2F%2Fwww.selectagents.gov%2FSelectAgentsandToxinsList.html. Accessed September 2020.

(July 30, 2018) CDC Bioterrorism [On-line information]. Available online at https://emergency.cdc.gov/bioterrorism/index.asp. Accessed September 2020.

Association of Public Health Laboratories. Laboratory Response Network. Available at https://www.aphl.org/programs/preparedness/Pages/LRN.aspx. Accessed September 2020.

(October 27, 2015) Biodefense and Emerging Infectious Diseases. National Institutes of Health. Available online at https://www.niaid.nih.gov/research/biodefense-emerging-infectious-diseases. Accessed September 2020.

Sources Used in Previous Reviews

Rapid Anthrax Test, Discovery’s Edge. Mayo Clinic Online Research Magazine (accessed December 2006). Available online at http://discoverysedge.mayo.edu/rapid_anthrax_test/.

Medical Laboratory Observer. The Observer, News: Polonium-210 (Accessed January 2007). PDF file available for download at http://www.mlo-online.com/articles/0107/0107observatory.pdf.

Center for Disease Control and Prevention. Emergency Preparedness and Response, Information about Polonium-210 in Recent Events in the United Kingdom (Online information, accessed January 2007). Available online at http://www.bt.cdc.gov/radiation/isotopes/polonium/qa.asp.

CDC. Emergency Preparedness and Response, Bioterrorism Agents/Diseases by category (Online information, accessed February 2007). Available online at http://www.bt.cdc.gov/agent/agentlist-category.asp#a.

(2011 January 5). Bioterrorism FAQs. American Medical Association [On-line information]. PDF available for download at http://www.ama-assn.org/ama1/pub/upload/mm/415/bioterrorism_faqs.pdf. Accessed January 2011.

(2011 January 5). Bioterrorism 101. American Medical Association [On-line information]. PDF available for download at http://www.ama-assn.org/ama1/pub/upload/mm/15/toolkit_bioterrorism.pdf. Accessed January 2011.

(Updated 2010 August 12). Bioterrorism. American Academy of Pediatrics [On-line information]. Available online at http://www.healthychildren.org/English/health-issues/conditions/infections/pages/Bioterrorism.aspx. Accessed January 2011.

Tunkel, A. (Revised 2009 December) Biological Warfare and Terrorism. Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merckmanuals.com/professional/sec14/ch167/ch167i.html?qt=bioterrorism&alt=sh. Accessed January 2011.

(Updated 2011 January 21). Building a Stronger Defense Against Bioterrorism. U.S. Food and Drug Administration, Consumer Update [On-line information]. Available online at http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm048251.htm. Accessed January 2011.

Dire, D. (Updated 2008 July 31). CBRNE – Biological Warfare Agents. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/829613-overview. Accessed January 2011.

Jagminas, L. (Updated 2011 January 12). CBRNE – Evaluation of a Biological Warfare Victim. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/830992-overview. Accessed January 2011.

Wright, J. et. al. (2010 July 23). Use of Anthrax Vaccine in the United States, Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2009. CDC, Morbidity and Mortality Weekly Report 59(rr06);1-30 [On-line information]. Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5906a1.htm?s_cid=rr5906a1_w. Accessed January 2011.

(Updated 2006 December 6). Facts About the Laboratory Response Network. CDC Emergency Preparedness and Response [On-line information]. Available online at http://www.bt.cdc.gov/lrn/factsheet.asp. Accessed January 2011.

Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 158-163.

(© 2014). Bioterrorism. The National Academy of Sciences [On-line information]. Available online at http://needtoknow.nas.edu/id/challenges/bioterrorism/. Accessed June 2014.

(Updated 2013 May 11) Bioterrorism. Healthychildren.org [On-line information]. Available online at http://www.healthychildren.org/English/health-issues/conditions/infections/pages/Bioterrorism.aspx. Accessed June 2014.

Sarkar-Tyson, M. and Atkins, H. (2011). Antimicrobials for Bacterial Bioterrorism Agents. Medscape Multispecialty from Future Microbiol. 2011;6(6):667-676. [On-line information]. Available online at http://www.medscape.com/viewarticle/745637. Accessed June 2014.

Jagminas, L. and Mothershead, J. (Updated 2013 October 14). CBRNE – Biological Warfare Mass Casualty Management. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/831529-overview. Accessed June 2014.

Jagminas, L. (Updated 2013 October 14). CBRNE – Evaluation of a Biological Warfare Victim. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/830992-overview. Accessed June 2014.

Dire, D. (Updated 2013 September 3). CBRNE – Biological Warfare Agents. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/829613-overview. Accessed June 2014.

(Updated 2013 February 11). Biological Threats. Ready.gov [On-line information]. Available online at http://www.ready.gov/biological-threats. Accessed June 2014.

(© 2014) Select Agents and Toxins List. CDC Federal Select Agent Program [On-line information]. Available online at http://www.selectagents.gov/SelectAgentsandToxinsList.html. Accessed February 2015.