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Biotoxins occupy a middle ground in the spectrum between chemical and biological agents (Table 17–1). Neither a living entity, such as bacteria, nor a laboratory invention, such as nerve gases, biotoxins are products of metabolic pathways that are toxic to humans. Some are made by single-celled organisms, whereas others are derived from multicellular organisms. Naturally occurring biotoxins may also be reproduced synthetically. Biotoxins can be extremely potent, but they are not communicable and do not replicate within the host. For this reason, properly decontaminated patients pose no risk to health care workers (HCWs) and others with whom they may come into contact. The clinical impact of biotoxins is arguably more akin to chemical weapons than to biological weapons; however their biological origins tie them in readily with biological weapons.

Table 17–1 Quick Facts: Botulism as a Bioweapon

Exposure to biotoxins occurs through ingestion, dermal absorbtion, or as an aerosol. Militarily or as a weapon of terror, aerosol forms of biotoxins pose the greatest risk not only in terms of numbers of people exposed, but the rapidity of symptom onset. With some of the biotoxins, inhalational effects are understood only from animal studies, leaving many open questions about how an inhalational exposure might present. Not all biotoxins are likely candidates for use as weapons of mass destruction or terrorist weapons. Due to their biological and physiochemical properties, Army biowarfare experts consider botulinum toxin and Staphylococcal Enterotoxin B (SEB) to be of most concern from the point of view of battlefield exposures. SEB, a so-called superantigen, causes hyperactivation of the immune system and prompt incapacitation (see Chapter 19). As a Category A agent, botulinum is discussed in its own chapter (Chapter 18).

Since terrorists may have more limited goals—for example, sowing fear, as was seen with anthrax—wider options in regard to potential biotoxin weapons, including ricin, abrin and mycotoxins, exist. This, too, is discussed briefly.

The CDC classifies the biotoxins as biological weapons. Others make biotoxins a category unto itself, or classify them as chemical agents. For the purposes of this text, we have chosen to follow the CDC categorization, thereby providing discussion of particular biotoxins according to their Category A and Category B biological weapons designation. The only exception is ricin, which although listed with Category B agents by ...

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