Biological and toxin weapons are either microorganisms like virus, 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. 

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.

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 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. 

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’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.

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. 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.