Acute agents are weaponized by some means of dispersal over a population, typically following an explosion (such as with a conventional artillery round) causing immediate defensive measures to be taken. Alternatively, a biological weapon can be used covertly such as deploying dispersent from the exhaust of an aircraft. In this instance the period of time between the suspicion of a BW dispersal and its detection on the ground could occur simultaneously with the onset of illness in people exposed to the agent.
By contrast, subtle biological weapons are characterized by agents where suspicion of the purposeful spread of a harmful agent may not arise for months, years, or even decades. Such agents might cause disease vastly different than those associated with acute agents and may manifest as an enhanced vulnerability of the exposed population to a disease directly or indirectly linked to the actual microbial agent. Correspondingly, this agent may cause enhanced susceptibility to a host of other chronic or debilitating human diseases, such as cancer, immunosuppression, or organ system failure. Causal links to human disease are not the only manifestation of subtle weapons, however. They can also manifest as disruption of the ecological or agricultural system and lead to subsequent economic disruption. Subtle biological weapons need not be deployed in the same manner as a conventional biological weapon. They may be spread by simply contaminating an agricultural field, barnyard, or water supply or by introducing a previously unknown and harmful species to a particular environmental system. Hence, not only is the scope of subtle biological weapons much broader in the types of health or economic problems they create, but also in the manner in which these weapons can cause harm to a population, a nation, or even a continent.
Subtle Biological Weapons, page 153
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