Biological warfare is the intentional use of living microorganisms or their toxic products for the purpose of destroying or reducing the military effectiveness of man. It is the exploitation of the inherent potential of infectious disease agents by scientific research and development, resulting in the production of BW weapons systems. Man may also be injured secondarily by damage to his food crops or domestic animals.

Biological warfare is considered to be primarily a strategic weapon. The major reason for this is that it has no quick kill effect. The incubation period of infectious disease, plus a variable period of illness even before a lethal effect, render this weapon unsuitable for hand-to-hand encounter. A man can be an effective fighting machine throughout the incubation period of most infectious diseases. Thus, an enemy would probably use this weapon for attack on static population centers such as large cities.

An important operational procedure in BW for an enemy would be to create an aerosol or cloud of agent over the target area. This concept has stimulated much basic research concerning the behavior of particulate biological materials, the pathogenesis of respiratory infections, the medical management of such diseases and defense against their occurrence.

The biological and physical properties of infectious particles have been studied intensively during the past fifteen years. Much new equipment and many unique techniques have been developed for the quantitative exposure of experimental animals to aerosols of infectious agents contained in particles of specified dimensional characteristics. Much information has been gathered relative to quantitative sampling and assessment techniques. Much of the older experimental work on respiratory infections was accomplished by very artificial procedures. The intra nasal instillation of a fluid suspension of infectious agent in an anesthetized animal is far different from exposure, through natural respiration, to aerosolized organisms.