All forms of botulism can be fatal and are considered medical emergencies. These rod-shaped organisms grow best in low oxygen conditions.
Foodborne botulism is a public health emergency because many people can be poisoned by eating a contaminated food. The bacteria form spores which allow them to survive in a dormant state until exposed to conditions that can support their growth.
There are seven types of botulism toxin designated by the letters A through G; only types A, B, E and F cause illness in humans. In the United States, an average of 145 cases is reported each year. Outbreaks of foodborne botulism involving two or more persons occur most years and are usually caused by home-canned foods.
Symptoms of botulism The classic symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness.
Infants with botulism appear lethargic, feed poorly, are constipated, and have a weak cry and poor muscle tone.
These are all symptoms of the muscle paralysis caused by the bacterial toxin.
In foodborne botulism, symptoms generally begin 18 to 36 hours after eating a contaminated food, but they can occur as early as 6 hours or as late as 10 days. Physicians may consider the diagnosis if the patient’s history and physical examination suggest botulism.
However, these clues are usually not enough to allow a diagnosis of botulism.
Other diseases such as Guillain-Barré syndrome, stroke, and myasthenia gravis can appear similar to botulism, and special tests may be needed to exclude these other conditions.
These tests may include a brain scan, spinal fluid examination, nerve conduction test (electromyography, or EMG), and a tensilon test for myasthenia gravis.
Tests for toxin and for bacteria that cause botulism can be performed at some state health department laboratories and at CDC.
Treatment of botulism The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks or months, plus intensive medical and nursing care. Botulism can be treated with an antitoxin which blocks the action of toxin circulating in the blood.