The intentional dissemination of disease adds a new dimension to threats posed by infectious and toxic agents. Bioterrorism is an issue for national security and law enforcement as well as a public health concern. Although the threat has a low probability of occurring, it does has severe consequences. Biological weapons are unique in their ability to inflict large numbers of casualties over a wide area with minimal logistical requirements and by means which can be virtually untraceable. Defense is complicated by the ease and low cost of producing an agent, the difficulty of detecting its presence, the logistics of protecting and treating victims, and the potential to selectively target humans, animals, or plants.

Available mechanisms include:

Aerosol delivery systems which generate long-lasting clouds of invisible suspended particles to contaminate food and water supplies and be absorbed through mucous membranes and damaged skin.

Direct contamination of consumables (crops).

Attempts to spread typical vector-borne diseases by releasing infected natural or unnatural arthropod hosts such as mosquitoes, ticks, or fleas.