Biological Agents

Unique identifier / Notation

BI0602

Synonyms

Biological weapons

Biological and toxin agents are either microorganisms like viruses, bacteria or fungi, or toxic substances produced by living organisms that are produced and released deliberately to cause disease and death in humans, animals or plants (WHO, no date).

Biological agents include bacteria, viruses, fungi, other microorganisms and their associated toxins. They have the ability to adversely affect human health in a variety of ways, ranging from relatively mild, allergic reactions to serious medical conditions-even death. In some forms, biological agents can also be weaponized for use in bioterrorism or other crimes (adapted from US OSHA, no date)

Primary reference(s)

WHO, no date. Biological weapons. World Health Organization (WHO). Accessed 6 April 2025.

US OSHA, no date. Biological Agents. Occupational Safety and Health Administration (US OSHA). Accessed 6 April 2025.

Annotations

Additional scientific description

Biological agents like anthrax, botulinum toxin and plague can pose a difficult public health challenge causing large numbers of deaths in a short amount of time. Biological agents, which are capable of secondary transmission, can lead to epidemics. An attack involving a biological agent may mimic a natural event, which may complicate the public health assessment and response. In case of war and conflict, high-threat pathogens laboratories can be targeted, which might lead to serious public health consequences (WHO, no date).

Biological weapons form a subset of a larger class of weapons sometimes referred to as unconventional weapons or weapons of mass destruction, which also includes chemical, nuclear and radiological weapons. The use of biological agents is a serious concern, and the risk of using these agents in a terrorist attack is thought to be increasing (WHO, no date).

WHO focuses on the possible public health consequences of an incident due to a biological agent, regardless of whether it is characterized as a deliberate act or a naturally occurring event (WHO, no date).

Bioterrorism involves intentionally releasing viruses, bacteria, or toxins to harm people, livestock, or crops. Bacillus anthracis, the cause of anthrax, is a likely agent for such attacks (CDC, 2025). For example, an anthrax attack can take various forms, such as through mailed letters or contaminated food or water. It could be released into the air, which can lead to anthrax spores being spread by wind or by being carried on people's belongings. Even a small amount of anthrax can infect many people (CDC, 2025).

As an example, Jernigan et al (2002) reported that in October 2001, the first inhalational anthrax case in the United States since 1976 was identified in a media company worker in Florida. A national investigation was initiated to identify additional cases and determine possible exposures to Bacillus anthracis. Surveillance was enhanced through health-care facilities, laboratories, and other means to identify cases, which were defined as clinically compatible illnesses with laboratory-confirmed B. anthracis infection. From October 4 to November 20, 2001, 22 cases of anthrax (11 inhalational, 11 cutaneous) were identified; 5 of the inhalational cases were fatal. Twenty (91%) case patients were either mail handlers or were exposed to worksites where contaminated mail was processed or received. B. anthracis isolates from four powder-containing envelopes, 17 specimens from patients, and 106 environmental samples were indistinguishable by molecular subtyping. Illness and death occurred not only at targeted worksites but also along the path of mail and in other settings. Continued vigilance for cases is needed among health-care providers and members of the public health and law enforcement communities (Jernigan et al., 2002).

Metrics and numeric limits

Assessment of treaty compliance is partly based on the understanding and application of a so-called General Purpose Criterion (GPC) as it pertains to 'hostile uses' or in 'armed conflict' (Article I). Since the Chemical Weapons Convention (CWC) covers toxins, the international legal prohibition against biological warfare should also be understood to include the 'method of warfare' (UNODA, 1972).

Grey areas exist with respect to formulations and applications that differ from those developed by historical state biological weapons programmes, including for behaviour modification or for use in situations outside the traditional understanding of state-to-state armed conflict such as peacekeeping or counter-terrorism operations.

Key relevant UN convention / multilateral treaty

The General Purpose Criterion, which is embodied in the Biological and Toxin Weapons Convention’s definition of prohibited activities, is the mechanism that ensures the Convention’s prohibitions remain comprehensive in scope, including in terms of scientific and technological developments (UNODA, 1972).

Drivers

Biological agents are devices or agents used or intended to be used in a deliberate attempt to disseminate disease-producing organisms or toxins using aerosol, food, water, or insect vectors. Their mechanism of action tends to be broadly through infection or intoxication noting the relative ease with which the agents may be deployed and their potentially devastating effects.

Impacts

If a biological attack goes unnoticed until doctors observe unusual illness patterns in emergency rooms and alert public health authorities, it could lead to many severe illnesses and deaths (CDC, 2025).

Multi-hazard context

Depends on the biological and toxin agents that are released such as viruses, bacteria or fungi, or toxic substances produced by living organisms that are produced and released deliberately to cause disease and death in humans, animals or plants (WHO, no date).

Risk Management

WHO is committed to saving lives and reducing suffering during times of crisis – whether caused by conflict, disease outbreak or a disaster. WHO’s Health Emergencies Programme is committed to working with Member States and other stakeholders so that suffering and death in crises are minimized and systems are protected and repaired (WHO, no date b).

WHO’s Health Emergencies Programme provides the following services to countries:

support of the assessment of country health emergency preparedness and development of national plans to address critical capacity gaps;
development of strategies and capacities to prevent and control high-threat infectious hazards; and
monitoring of new and ongoing public health events to assess, communicate and recommend action for public health risks (WHO, no date b).

In addition, WHO will work with countries and partners to:

ensure readiness to diminish public health risks in countries with high vulnerability; and
provide life-saving health services to affected populations in countries with ongoing emergencies (WHO, no date b).

When a Member State is concerned about biological agents and wants to be better prepared, WHO advises strengthening public health surveillance and response activities, with an emphasis on:

more effective national surveillance of outbreaks of illness, including alert and response systems at all levels that can detect diseases that may be deliberately caused;
improved biosafety and biosecurity throughout the health sector;
better communication between multiple sectors, including public health, animal health, water supply, food safety, poison control, civil protection, law enforcement, and security services;
improved assessments of vulnerability, and effective communication about risks and threats to both professionals and the public;
preparation for handling the psychosocial consequences of the deliberate use of pathogens to cause harm; and
contingency plans for an enhanced response capacity by all sectors (WHO, no date).

With the occurrence of a potential, suspected or confirmed deliberate biological event, WHO would, upon the invitation of the affected Member State(s), work closely with the Member State government(s), other UN agencies, and other international partners as appropriate, support the event response, and assess and mitigate the public health consequences (WHO, no date). These activities could include:

working with relevant international or national organizations to better characterize the nature, scope and impact of the event;
facilitating the public health investigation of the event, including referral to appropriate laboratories for confirmation and characterization of the pathogen;
offering targeted training to public health responders;
facilitating the identification and acquisition of necessary materials (such as personal protective equipment) appropriate to the event;
supporting the continued delivery of essential health services; and
developing guidance material specific to the pathogen or toxin in question (WHO, no date).

Monitoring

WHO supports countries to conduct all-hazards strategic risk assessment in the contexts of health emergencies and disasters, which results in the development of a country's risk profile. Empowered with the country risk profile, inclusive of a seasonal risk calendar, countries can anticipate potential emergencies before they occur to trigger early alerts and inform early actions (WHO, 2021).

WHO's Early Warning, Alert and Response System (EWARS) has been designed to improve disease outbreak detection in emergency settings, such as in countries in conflict or following a natural disaster. It is a simple and cost-effective way to rapidly set up a disease surveillance system. EWARS is deployed during an emergency as an adjunct to the national disease surveillance system. WHO works with Ministries of Health and health sector partners to train local health workers to use the system. After the emergency, EWARSs should re-integrate back into the national system (WHO, no date c).

WHO's global alert and response activities and the Global Outbreak Alert and Response Network (GOARN) represent a major pillar of global health security aimed at the detection, verification and containment of epidemics. In the event of the intentional release of a biological agent, these activities would be vital to effective international containment efforts (WHO, no date).