Botulinum neurotoxins inhalational botulism

Data sources (1) Holzer E. Botulism caused by inhalation. Med Klin. 1962 41 1735-1740. (2) Franz DR, Pitt LM, Clayton MA, Hanes MA, Rose KJ. Efficacy of prophylactic and therapeutic administration of antitoxin for inhalation botulism. In Das Gupta B, ed. Botulinum and Tetanus Neurotoxins and Biomedical Aspects. New York, NY Plenum Press 1993 473-476. 

Botulinum neurotoxins (BoNTs) are produced by the anaerobic Clostridium botulinum species of bacteria and are the cause of botulism, a life-threatening neuroparalytic disease. They are extremely potent food poisons, with a mouse LD50 of 0.1 ng/kg for type A [1,2]. Aerosol exposure of BoNTs does not occur naturally, but could be attempted by bioterrorists to achieve a widespread effect. It has been estimated that a single gram of crystalline toxin, evenly dispersed and inhaled, could kill more than one million people [2]. 

Chemical Abstracts Service Registry Number CAS 93384-43-1. Botulinum toxins comprise a series of seven related protein neurotoxins that prevent fusion of synaptic vesicles with the presynaptic membrane and thus prevent release of acetylcholine. Exposure in a battlefield or terrorist setting would most likely be to inhaled aerosolized toxin. The clinical presentation is that of classical botulism, with descending skeletal muscle weakness (with an intact sensorium) progressing to respiratory paralysis. A toxoid vaccine is available for prophylaxis, and a pentavalent toxoid can be used following exposure its effectiveness wanes rapidly, however, after the end of the clinically asymptomatic latent period. Because treatment is supportive and intensive (involving long-term ventilatory support), the use of botulinum toxin has the potential to overwhelm medical resources especially at forward echelons of care. 

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