Botulism in the United States: a clinical and epidemiologic review

Botulism is caused by a neurotoxin produced from the anaerobic, spore-forming bacterium Clostridium botulinum. Botulism in humans is usually caused by toxin types A, B, and E. Since 1973, a median of 24 cases of foodborne botulism, 3 cases of wound botulism, and 71 cases of infant botulism have been reported annually to the Centers for Disease Control and Prevention (CDC). New vehicles for transmission have emerged in recent decades, and wound botulism associated with black tar heroin has increased dramatically since 1994. Recently, the potential terrorist use of botulinum toxin has become an important concern. Botulism is characterized by symmetric, descending, flaccid paralysis of motor and autonomic nerves, usually beginning with the cranial nerves. Blurred vision, dysphagia, and dysarthria are common initial complaints. The diagnosis of botulism is based on compatible clinical findings; history of exposure to suspect foods; and supportive ancillary testing to rule out other causes of neurologic dysfunction that mimic botulism, such as stroke, the Guillain-Barré syndrome, and myasthenia gravis. Laboratory confirmation of suspected cases is performed at the CDC and some state laboratories. Treatment includes supportive care and trivalent equine antitoxin, which reduces mortality if administered early. The CDC releases botulism antitoxin through an emergency distribution system. Although rare, botulism outbreaks are a public health emergency that require rapid recognition to prevent additional cases and to effectively treat patients. Because clinicians are the first to treat patients in any type of botulism outbreak, they must know how to recognize, diagnose, and treat this rare but potentially lethal disease.