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{{short description|Pathogen that can be weaponized}}
{{about|harmful biological agents|therapeutic biological drugs|Biopharmaceutical}}
{{redirect|Biological weapon|natural weapons in biology|Weapon (biology)}}
{{Weapons of mass destruction}}
[[Image:Building on the site of the Harbin bioweapon facility of Unit 731 関東軍防疫給水部本部731部隊（石井部隊）日軍第731部隊旧址 PB121165.JPG|thumb|260px|right|A bacteriological weapon that was in use by the Japanese Army's [[Unit 731]] in [[China]] .<ref>{{Cite web|date=21 April 2024|url=https://www.youtube.com/watch?v=CJhcPWp6Ilo|title=「標本室は目の開けられないくらい･･･」731部隊の実態、元少年兵の目に焼きついた光景【報道特集】 |publisher=TBS News|accessdate=2024-07-02}}</ref>]]
[[Image:1993 Kameido site fluid petri.jpg|thumb|A [[Microbiological culture|culture]] of ''[[Bacillus anthracis]]'', the causative agent of [[anthrax]]]]
'''Biological agents''', also known as '''biological weapons''' or '''bioweapons''', are [[pathogens]] used as weapons. In addition to these living or replicating [[pathogens]], [[toxin]]s and [[Toxin#Biotoxins|biotoxins]] are also included among the bio-agents. More than 1,200 different kinds of potentially weaponizable bio-agents have been described and studied to date, and experts expect that in the future it will be possible to design novel biological weapons.<ref>{{Cite report | last1 = Manheim | first1 = David | last2 = Williams | first2 = Adeline | last3 = Aveggio | first3 = Casey | last4 = Berke | first4 = Allison | title = Understanding the Theoretical Limits of AI-Enabled Pathogen Design: Insights from a Delphi Study | publisher = RAND Corporation | location = Santa Monica, CA | date = 2025 | url = https://www.rand.org/pubs/research_reports/RRA4087-1.html | type = Research Report | series = RAND Research Report | number = RR-A4087-1 | doi = 10.7249/RRA4087-1 | pages = 123 | access-date = 29 October 2025| url-access = subscription }}</ref>

Some biological agents have the ability to adversely affect [[health|human health]] in a variety of ways, ranging from relatively mild [[allergy|allergic reactions]] to serious medical conditions, including serious injury, as well as serious or permanent disability or [[death]]. Many of these organisms are ubiquitous in the [[natural environment]] where they are found in water, soil, plants, or animals.<ref name="Biological Agents">{{cite web|url= https://www.osha.gov/SLTC/biologicalagents/index.html|title=Biological Agents |publisher= United States Department of Labor: OSHA|access-date=2012-05-31}}</ref> Bio-agents may be amenable to "weaponization" to render them easier to deploy or disseminate. [[Genetic engineering|Genetic modification]] may enhance their incapacitating or lethal properties, or render them impervious to conventional treatments or preventives. Since many bio-agents reproduce rapidly and require minimal resources for propagation, they are also a potential danger in a wide variety of occupational settings.<ref name="Biological Agents"/>

The 1972 [[Biological Weapons Convention]] is an international treaty banning the development, use or stockpiling of biological weapons; as of March 2021, there were 183 states parties to the treaty.<ref name=":1" /> Bio-agents are, however, widely studied for both defensive and [[medical research]] purposes under various [[biosafety levels]] and within [[biocontainment]] facilities throughout the world.

==Classifications==
===Operational===
The former [[United States biological weapons program]] (1943–1969) categorized its weaponized anti-personnel bio-agents as either "lethal agents" (''[[Bacillus anthracis]]'', ''[[Francisella tularensis]]'', [[Botulinum toxin]]) or "incapacitating agents" (''[[Brucella suis]]'', ''[[Coxiella burnetii]]'', [[Venezuelan equine encephalitis virus]], [[Enterotoxin type B|staphylococcal enterotoxin B]]).<ref>Headquarters, Departments of the Army, the Navy, and the Air Force, and Commandant, Marine Corps (17 July 2000), ''Field Manual: Treatment of Biological Warfare Casualties'' (Army FM 8-284/Navy NAVMED P-5042/Air Force AFMAN (I) 44-156/Marine Corps MCRP 4-11.1C), para 1-4 (pg 1-3).</ref>

===Legal===
Since 1997, United States law has declared a list of bio-agents designated by the [[U.S. Department of Health and Human Services]] or the [[U.S. Department of Agriculture]] that have the "potential to pose a severe threat to public health and safety" to be officially defined as "[[select agents]]" and possession or transportation of them are tightly controlled as such.<ref>''Additional Requirements for Facilities Transferring or Receiving Select Agents'', Title 42 CFR Part 72 and Appendix A; 15 April 1997 (DHHS).</ref> Select agents are divided into "HHS select agents and toxins", "USDA select agents and toxins" and "Overlap select agents and toxins".

===Regulatory===
The US [[Centers for Disease Control and Prevention]] (CDC) breaks biological agents into three categories: [[Bioterrorism#Types of agents|Category A, Category B, and Category C]]. Category A agents pose the greatest threat to the US. Criteria for being a Category "A" agent include high rates of morbidity and mortality, ease of dissemination and communicability, ability to cause a public panic, and special action required by public health officials to respond. Category A agents include [[anthrax]], [[botulism]], [[Plague (disease)|plague]], [[smallpox]], and viral hemorrhagic fevers.

==List of bio-agents of military importance==
:''The following pathogens and toxins were weaponized by one nation or another at some time. NATO [[CB military symbol|abbreviations]] are included where applicable.''

===Bacterial bio-agents===
{| class ="wikitable sortable"
|-
! Disease
! Causative agent ([[chemical weapon designation|military symbol]])
|-
| [[Anthrax]]
| ''[[Bacillus anthracis]]'' (N or TR)
|-
| [[Brucellosis|Brucellosis (bovine)]]
| ''[[Brucella abortus]]''
|-
| [[Brucellosis|Brucellosis (caprine)]]
| ''[[Brucella melitensis]]'' (AM or BX)
|-
| [[Brucellosis|Brucellosis (porcine)]]
| ''[[Brucella suis]]'' (US, AB or NX)
|-
| [[Cholera]]
| ''[[Vibrio cholerae]]'' (HO)
|-
| [[Diphtheria]]
| ''[[Corynebacterium diphtheriae]]'' (DK)
|-
| [[Dysentery|Dysentery (bacterial)]]
| ''[[Shigella dysenteriae]]'', ''[[Escherichia coli]]'' (Y)
|-
| [[Glanders]]
| ''[[Burkholderia mallei]]'' (LA)
|-
| [[Listeriosis]]
| ''[[Listeria monocytogenes]]'' (TQ)
|-
| [[Melioidosis]]
| ''[[Burkholderia pseudomallei]]'' (HI)
|-
| [[Plague (disease)|Plague]]
| ''[[Yersinia pestis]]'' (LE)
|-
| [[Tularemia]]
| ''[[Francisella tularensis]]'' (SR or JT)
|}

===Chlamydial bio-agents===
{| class ="wikitable sortable"
|-
! Disease
! Causative agent ([[chemical weapon designation|military symbol]])
|-
| [[Psittacosis]]
| ''[[Chlamydophila psittaci]]'' (SI)
|}

===Rickettsial bio-agents===
{| class ="wikitable sortable"
|-
! Disease
! Causative agent ([[chemical weapon designation|military symbol]])
|-
| [[Q fever]]
| ''[[Coxiella burnetii]]'' (OU)
|-
| [[Rocky Mountain spotted fever]]
| ''[[Rickettsia rickettsii]]'' (RI or UY)
|-
| [[Epidemic typhus|Typhus (human)]]
| ''[[Rickettsia prowazekii]]'' (YE)
|-
| [[Murine typhus|Typhus (murine)]]
| ''[[Rickettsia typhi]]'' (AV)
|}

===Viral bio-agents===
{| class ="wikitable sortable"
|-
! Disease
! Causative agent ([[chemical weapon designation|military symbol]])
! Comments
|-
| [[Eastern equine encephalitis virus|Equine encephalitis (Eastern)]]
| [[Eastern equine encephalitis virus]] (ZX)
|
|-
| [[Venezuelan equine encephalitis virus|Equine encephalitis (Venezuelan)]]
| [[Venezuelan equine encephalitis virus]] (FX)
|
|-
| [[Western equine encephalitis virus|Equine encephalitis (Western)]]
| [[Western equine encephalitis virus]] (EV)
|
|-
| [[Japanese B encephalitis]]
| [[Japanese encephalitis virus]] (AN)
|
|-
| [[Marburg virus disease|Marburg hemorrhagic fever]] (Marburg HF)
| [[Marburg virus]] (MARV)
| by the Soviet Union<ref>[[Kenneth Alibek]] and S. Handelman. ''Biohazard: The Chilling True Story of the Largest Covert Biological Weapons Program in the World - Told from Inside by the Man Who Ran it''. 1999. Delta (2000) {{ISBN|0-385-33496-6}}.</ref>
|-
| [[Rift Valley fever]]
| [[Rift Valley fever|Rift Valley fever virus]] (FA)
|
|-
| [[Smallpox]]
| [[Variola virus]] (ZL)
|
|-
| [[Yellow fever]]
| [[Yellow fever virus]] (OJ or LU)
|
|}

===Mycotic bio-agents===
{| class ="wikitable sortable"
|-
! Disease
! Causative agent ([[chemical weapon designation|military symbol]])
|-
| [[Coccidioidomycosis]]
| ''[[Coccidioides immitis]]'' (OC)
|}

===Biological toxins===
{| class ="wikitable sortable"
|-
! Toxin
! Source of toxin ([[chemical weapon designation|military symbol]])
|-
|[[Abrin]]
|[[Rosary pea]] (''Abrus precatorius)''
|-
| [[Botulinum toxin|Botulinum toxins (A through G)]]
| ''Clostridium botulinum'' bacteria or spores, and several other Clostridial species. (X or XR)
|-
| [[Ricin]]
| [[Castor bean]] (''Ricinus communis'') (W or WA)
|-
| [[Saxitoxin]]
| Various marine and brackish cyanobacteria, such as ''[[Anabaena]]'', ''[[Aphanizomenon]]'', ''[[Lyngbya]]'', and ''[[Cylindrospermopsis]]'' (TZ)
|-
| [[Staphylococcal enterotoxin B]]
| ''[[Staphylococcus aureus]]'' (UC or PG)
|-
| [[Tetrodotoxin]]
| Various marine bacteria, including ''[[Vibrio alginolyticus]]'', ''[[Pseudoalteromonas tetraodonis]]'' (PP)
|-
| [[Trichothecene]] [[mycotoxins]]
| Various species of fungi, including ''[[Fusarium]]'', ''[[Trichoderma]]'', and ''[[Stachybotrys]]''
|}

===Biological vectors===
{| class ="wikitable sortable"
|-
! Vector ([[chemical weapon designation|military symbol]])
! Disease
|-
| [[Mosquito]] (''[[Aedes aegypti]]'') (AP)
| [[Malaria]], [[Dengue fever]], [[chikungunya]], [[yellow fever]], other [[arbovirus]]es
|-
| [[Oriental flea]] (''[[Xenopsylla cheopis]]'')
| [[Plague (disease)|Plague]], [[murine typhus]]
|}

===Simulants===
Simulants are organisms or substances which mimic physical or biological properties of real biological agents, without being pathogenic. They are used to study the efficiency of various dissemination techniques or the risks caused by the use of biological agents in [[bioterrorism]].<ref>{{Cite news|url=https://nightferry.wordpress.com/biological-warfare-bw-simulants-%E2%80%93-bacillus-globigii-bg/|title=Biological Warfare (BW) Simulants – ''Bacillus globigii'' (BG)|date=2010-02-05|work=The Night Ferry|access-date=2017-04-03|language=en-US}}</ref> To simulate dispersal, attachment or the penetration depth in human or animal lungs, simulants must have particle sizes, specific weight and surface properties, similar to the simulated biological agent.

The typical size of simulants (1–5&nbsp;μm) enables it to enter buildings with closed windows and doors and penetrate deep into the lungs. This bears a significant health risk, even if the biological agent is normally not pathogenic.
* ''[[Bacillus globigii]]'' (historically named ''Bacillus subtilis'' in the context of bio-agent simulants) (BG, BS, or U)
* ''[[Serratia marcescens]]'' (SM or P)
* ''[[Aspergillus fumigatus]]'' mutant C-2 (AF)
* ''[[Escherichia coli]]'' (EC)
* ''[[Bacillus thuringiensis]]'' (BT)
* ''Erwinia herbicola'' (current accepted name: ''[[Pantoea agglomerans]])'' (EH)
* Fluorescent particles such as [[zinc cadmium sulfide]], ZnCdS (FP)

== International law ==
[[File:Biological Weapons Convention original document.png|thumb|The Biological Weapons Convention<ref>United Nations (1972). [https://front.un-arm.org/wp-content/uploads/2020/12/BWC-text-English.pdf Biological Weapons Convention].</ref>]]
{{Main|Geneva Protocol|Biological Weapons Convention}}

While the [[History of biological warfare|history of biological weapons use]] goes back more than six centuries to the [[siege of Caffa]] in 1346,<ref>{{Cite journal|last=Wheelis|first=Mark|date=September 2002|title=Biological Warfare at the 1346 Siege of Caffa|journal=Emerging Infectious Diseases|language=en-us|volume=8|issue=9|pages=971–975 |doi=10.3201/eid0809.010536|pmid=12194776 |pmc=2732530 |doi-access=free}}</ref> international restrictions on biological weapons began only with the 1925 [[Geneva Protocol]], which prohibits the use but not the possession or development of chemical and biological weapons in international armed conflicts.<ref>{{Cite web|title=Text of the 1925 Geneva Protocol|url=http://disarmament.un.org/treaties/t/1925/text|url-status=live|access-date=2021-03-02|publisher=[[United Nations Office for Disarmament Affairs]]|archive-url=https://web.archive.org/web/20150408104523/http://disarmament.un.org:80/treaties/t/1925/text |archive-date=2015-04-08 }}</ref> Upon ratification of the Geneva Protocol, several countries made [[Reservation (law)|reservations]] regarding its applicability and use in retaliation.<ref>{{Cite web|title=Disarmament Treaties Database: 1925 Geneva Protocol|url=http://disarmament.un.org/treaties/t/1925|url-status=live|access-date=2021-03-02|publisher=[[United Nations Office for Disarmament Affairs]]|archive-url=https://web.archive.org/web/20130825083028/http://disarmament.un.org:80/treaties/t/1925 |archive-date=2013-08-25 }}</ref> Due to these reservations, it was in practice a "[[No first use|no-first-use]]" agreement only.<ref>{{Cite journal|last=Beard|first=Jack M.|date=April 2007|title=The Shortcomings of Indeterminacy in Arms Control Regimes: The Case of the Biological Weapons Convention|url=https://www.cambridge.org/core/journals/american-journal-of-international-law/article/abs/shortcomings-of-indeterminacy-in-arms-control-regimes-the-case-of-the-biological-weapons-convention/F0FCA907A496B488DEE91630C812C6DE|journal=American Journal of International Law|language=en|volume=101|issue=2|pages=277|doi=10.1017/S0002930000030098|s2cid=8354600 |issn=0002-9300|url-access=subscription}}</ref>

The 1972 Biological Weapons Convention supplements the Geneva Protocol by prohibiting the development, production, acquisition, transfer, stockpiling and use of biological weapons.<ref name=":0">{{Cite web|title=Biological Weapons Convention|url=https://www.un.org/disarmament/biological-weapons/|url-status=live|archive-url=https://web.archive.org/web/20210215200800/https://www.un.org/disarmament/biological-weapons|archive-date=2021-02-15|access-date=2021-03-02|publisher=[[United Nations Office for Disarmament Affairs]]|language=en-US}}</ref> Having entered into force on 26 March 1975, this agreement was the first multilateral disarmament treaty to ban the production of an entire category of weapons of mass destruction.<ref name=":0" /> As of March 2021, [[List of parties to the Biological Weapons Convention|183 states have become party to the treaty]].<ref name=":1">{{Cite web|title=Disarmament Treaties Database: Biological Weapons Convention|url=http://disarmament.un.org/treaties/t/bwc|url-status=live|access-date=2021-03-02|publisher=[[United Nations Office for Disarmament Affairs]]|archive-url=https://web.archive.org/web/20130303154241/http://disarmament.un.org/treaties/t/bwc/ |archive-date=2013-03-03 }}</ref> The treaty is considered to have established a strong global norm against biological weapons,<ref>{{Cite journal|last1=Cross|first1=Glenn|last2=Klotz|first2=Lynn|date=2020-07-03|title=Twenty-first century perspectives on the Biological Weapon Convention: Continued relevance or toothless paper tiger|journal=Bulletin of the Atomic Scientists|volume=76|issue=4|pages=185–191|doi=10.1080/00963402.2020.1778365|bibcode=2020BuAtS..76d.185C |issn=0096-3402|doi-access=free}}</ref> which is reflected in the treaty's preamble, stating that the use of biological weapons would be "repugnant to the conscience of mankind".<ref>{{Cite web|title=Preamble, Biological Weapons Convention|url=http://disarmament.un.org/treaties/t/bwc/text|url-status=live|access-date=2021-03-02|publisher=[[United Nations Office for Disarmament Affairs]]|archive-url=https://web.archive.org/web/20140306222659/http://disarmament.un.org/treaties/t/bwc/text |archive-date=2014-03-06 }}</ref> However, its effectiveness has been limited due to insufficient institutional support and the absence of any formal verification regime to monitor compliance.<ref>{{Cite book|last=Dando|first=Malcolm|title=Chapter 9: The Failure of Arms Control, In Bioterror and Biowarfare: A Beginner's Guide|publisher=Oneworld|year=2006|isbn=9781851684472|pages=146–165}}</ref>

In 1985, the [[Australia Group]] was established, a multilateral export control regime of 43 countries aiming to prevent the proliferation of chemical and biological weapons.<ref>{{Cite web|title=The Origins of the Australia Group|url=https://www.dfat.gov.au/publications/minisite/theaustraliagroupnet/site/en/origins.html|url-status=live|archive-url=https://web.archive.org/web/20210302091850/https://www.dfat.gov.au/publications/minisite/theaustraliagroupnet/site/en/index.html|archive-date=2021-03-02|access-date=2021-03-02|publisher=Australian Department of Foreign Affairs and Trade}}</ref>

In 2004, the [[United Nations Security Council]] passed [[United Nations Security Council Resolution 1540|Resolution 1540]], which obligates all UN Member States to develop and enforce appropriate legal and regulatory measures against the proliferation of [[Chemical weapon|chemical]], biological, [[Radiological weapon|radiological]], and [[nuclear weapon]]s and their means of delivery, in particular, to prevent the spread of weapons of mass destruction to [[non-state actor]]s.<ref>{{Cite web|title=1540 Committee|url=https://www.un.org/en/sc/1540/about-1540-committee/general-information.shtml|url-status=live|archive-url=https://web.archive.org/web/20200220050416/https://www.un.org/en/sc/1540/about-1540-committee/general-information.shtml|archive-date=2020-02-20|access-date=2021-03-02|publisher=[[United Nations]]|language=en}}</ref>

==In popular culture==
{{main|Biological warfare in popular culture}}

==See also==
* [[Biological hazard]]
* [[Biological contamination]]
* [[Laboratory Response Network]]
* [[Pulsed ultraviolet light]]

==References==
{{Reflist}}

==External links==
* Rafał L. Górny, [https://oshwiki.eu/wiki/Biological_agents Biological agents], [https://oshwiki.eu/wiki/OSHwiki:About OSHwiki] ({{Webarchive|url=https://web.archive.org/web/20230130221701/https://oshwiki.eu/wiki/OSHwiki:About |date=2023-01-30 }})
* [https://www.osha.gov/biological-agents Biological Agents], OSHA
* [https://www.selectagents.gov/sat/list.htm Select Agents and Toxins], Centers for Disease Control and Prevention
* [https://nonproliferation-elearning.eu/learningunits/biological-weapons/ Biological weapons e-learning module in the EU's non-proliferation and disarmament course] (taught by [[Filippa Lentzos]])

{{Bioterrorism}}
{{Doomsday}}
{{U.S. biological defense}}
{{U.S.S.R. biological weapons}}
{{Weapons}}

[[Category:Biological agents| ]]
[[Category:Biological contamination]]