Botulism: Countering Common Clinical Misperceptions

Agam Rao, MD


April 01, 2013

Editorial Collaboration

Medscape &

In This Article

Diagnosis and Treatment of Non-infant Botulism

During 2005-2011, 985 cases of botulism were confirmed in the United States, with 310 cases in individuals over the age of 1 year.[2] The remainder of this commentary will focus on diagnosis and treatment of non-infant botulism. According to the textbook description, botulism:

Manifests as a descending paralysis in a bilateral and symmetric fashion;

Begins with cranial nerve deficits that can occur in any combination and manifest as double vision, blurry vision, difficulty swallowing, ptosis; difficulty moving the eyes, and facial paralysis;

Can progress to weakness in proximal muscles before distal muscles and can progress to complete flaccid paralysis;

Is an acute process that does not wax or wane;

Does not alter sensorium; and

Can progress to respiratory failure and even death if patients are not intubated and mechanically ventilated.[1,3,4]

Botulism Can Be Confused With Other Illnesses

Like many illnesses, botulism sometimes deviates from the textbook description. Other neurological disorders resembling botulism include myasthenia gravis and Guillain-Barré syndrome. They are difficult to differentiate from botulism in the early work-up. We are trained to think that common things occur more frequently, therefore a rare disease such as botulism might not be considered until late in the hospital course, if at all. The diagnosis of botulism is made by a mouse bioassay that is available only through public health laboratories[5] This means that clinicians have to consider botulism before testing is done. Routine clinical cultures do not diagnose botulism.

Don't Wait to Consider Botulism

Botulism is a public health emergency because of the lethal nature of the illness and the potential for a single case to be the harbinger of many, if it is the first case in a foodborne outbreak. Botulinum antitoxin is most effective when given early in the clinical course: it does not reverse existing signs and symptoms. If a patient is already completely paralyzed, antitoxin will not reverse the paralysis.[6] Considering botulism early in the work-up as you look for other more common diseases will save critical time and can influence survival.

When a physical examination indicates a descending paralysis, consider evaluating the patient for common causes, such as stroke and infection, with brain imaging and lumbar puncture. You might also consider an edrophonium test and electromyography if these can be performed quickly.

What to Do if Botulism Is on the Differential

Because time is of the essence, state health departments and CDC are available anytime, day or night, for botulism consultation and antitoxin release. In the United States, CDC is the only source of antitoxin. If you suspect botulism, you should contact your state health department, and they will contact CDC. Laboratory testing for botulism is coordinated at the time of consultation with public health agencies and is generally performed only if antitoxin has been released. Do not wait to administer antitoxin pending results of laboratory testing because testing can take more than a week. By that time, antitoxin may no longer be helpful.