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Biological Warfare (cont.)

Botulinum Toxin

Botulinum toxins are the most deadly toxins known. Because botulinum toxin is so lethal and easy to manufacture and weaponize, it represents a credible threat as a biological warfare agent. When used in this manner, exposure is likely to occur following inhalation of aerosolized toxin or ingestion of food contaminated with the toxin or its microbial spores. Iraq admitted to active research on the offensive use of botulinum toxins and to weaponizing and deploying more than 100 munitions with botulinum toxin in 1995.

All seven subtypes (A-G) of botulinum toxin act in similar ways. The toxin produces similar effects whether ingested, inhaled, or via a wound. The time course and severity of illness vary with route of exposure and dose received. Symptom onset is slower after inhalation exposure.

Signs and Symptoms

Symptoms may occur hours to several days after exposure. Initial signs and symptoms include blurred vision, dilated pupils, difficulty swallowing, difficulty speaking, an altered voice, and muscle weakness. After 24-48 hours, muscle weakness and paralysis may cause the person to be unable to breathe. Varying degrees of muscular weakness may occur.


Paralysis may indicate the presence of this exposure. Typical laboratory tests generally are not helpful, although special tests of nerve conduction and muscle response may be useful. Infection by inhalation can be diagnosed from nasal swabs up to 24 hours after exposure.


The most serious complication is respiratory failure. With attention to symptoms and help breathing, sometimes with a ventilator, death occurs in fewer than 5% of cases. For confirmed exposures, an antitoxin is available from the CDC. This antitoxin has all of the disadvantages of horse serum products, including the risks for shock and serum sickness. Skin testing is performed first by injecting a small amount of the antitoxin into the skin and then monitoring the person for 20 minutes.


The only botulinum vaccine was discontinued by the CDC in 2011.

Medically Reviewed by a Doctor on 11/20/2017

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