Although death was a frequent outcome in the past, it rarely occurs today. Before 1950 or so, foodborne botulism carried a mortality rate of 60%-70%. That rate dropped to 3% for all the different types of botulism between 1975 and 2009. Two principal causes of early death are complete airway obstruction from a food bolus as the muscles of deglutition become paralyzed and suffocation with paralysis of the diaphragm and intercostal muscles.
Once introduced into the body, the toxin enters the neuronal cells at the voluntary motor and autonomic neuromuscular junctions. There, it disrupts the release of neurotransmitter (acetylcholine) across the junction. With acetylcholine transmission blocked, the receptor sites of the motor and autonomic cells lie vacant. Flaccid paralysis occurs.[2,3] This process cannot be reversed. It may take months for the regeneration of the neurotransmitter mechanics.
The initial manifestations of botulism may be misleading. A patient who presents at the early stage may be alert and afebrile. The patient may sense the minute anatomic changes, but these subjective concerns are subtle and may be attributed to more typical maladies. Common misdiagnoses at this stage include alcohol or drug intoxication and psychiatric disorders. Later, the neurologic signs become dominant, and botulism may be misdiagnosed as stroke, Tolosa-Hunt syndrome, meningitis, myasthenia gravis, tick paralysis, or Guillain-Barré syndrome.[1,2,5,6,7]
Rarely, the gastrointestinal manifestations of botulism may predate or obscure the classic neurologic symptoms.[2,3] Botulism has been mistaken for acute bowel obstruction.[8,9] It is not until the neurologic manifestations come to the forefront that the correct diagnosis is made. In the patient in this case, the early ptosis was mistaken for lack of sleep and the xerostomia for dehydration. Nevertheless, the workup for a bowel obstruction (ie, abdominal radiographs and a CT scan of the abdomen with contrast) was reasonable because it is a more common disorder.
In-depth questioning of this patient revealed that several days before she came to the ED, she opened and tasted a batch of canned jalapeño peppers she had made a few months earlier. She was planning to take them to a parish food drive. Her husband and son did not consume any of the peppers.
Once botulism is included in the differential diagnosis, three actions must occur. First, the patient's status must be NPO to prevent aspiration. Second, assessment of respiratory capabilities is critical. It can be accomplished through various measurements, such as negative inspiratory force, vital capacity, blood gas analysis, or capnography.[1,2] Carbon dioxide retention requires immediate consideration of aggressive airway management to counter respiratory paralysis and cardiorespiratory arrest. Third, the local public health department and the Centers for Disease Control and Prevention (CDC) must be notified. Any case of botulism in a community is a public health emergency. An urgent epidemiologic investigation must begin to search for additional cases and the source of the outbreak (eg, restaurants).
Meanwhile, electrodiagnostic studies may be used to evaluate muscle weakness. Laboratory studies to confirm botulism include testing for neurotoxin in the serum, stool, and gastric juices; identifying clostridia in stool or wound cultures; and investigating the suspected sources of the toxin release. The mouse bioassay remains the gold standard. Real-time polymerase chain reaction and mass spectrometry are also helpful. However, waiting for the results of these studies cannot delay communication with the CDC once botulism is suspected.
The CDC has the responsibility for releasing Botulinum Antitoxin Heptavalent (A, B, C, D, E, F, G) (Equine) (BAT). It is free and is available to clinicians 24 hours a day, 7 days a week. Early administration of the antitoxin is associated with fewer days in the hospital and intensive care unit and a reduced need for mechanical ventilation support.[2,10,11] BAT neutralizes only the toxin circulating in the bloodstream that has yet to be incorporated into the cells. In 2015, at a botulism mass casualty incident at a potluck meal in Lancaster, Ohio, the antitoxin was requested at 10 AM but did not arrive until midnight.[12,13] Therefore, the CDC should be contacted expeditiously. Note that Botulism Immune Globulin Intravenous (Human) (BIG-IV) (BabyBIG), the specific immunoglobulin G for infants with botulism who are younger than 1 year of age, is requested through the California Department of Public Health Infant Botulism Treatment and Prevention Program.[2,14]
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