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Monday, February 18, 2013

The Dangers of Home Canning: A Case of Botulism

In the current issue of The Annals of Pharmacotherapy, a case is reported of a 60-year-old man who presents to an urgent care center with blurry vision, double vision, and difficulty speaking. The doctor is concerned that he may be having signs and symptoms of a stroke and sends him to the Emergency Room (ER) for evaluation.

A stroke is a burst artery (a type of blood vessel that carries blood away from the heart) or a blockage of an artery in the brain.

In the ER, the physical examination and diagnostic imaging of the brain showed no evidence of stroke. So the doctor orders standard blood tests but they do not yield anything of significance. The doctor wants to do some more studies and admits the patient to the hospital. A more sensitive imaging study of the brain was ordered the next day but the patient could not lie down due to a choking feeling. He was transferred to the intensive care unit (ICU) that day due to difficulty swallowing, difficulty speaking, nausea, dizziness, mild tremors in the arms and legs, and eyelid drooping. A test of heart functioning was normal. The next day, due to worsening breathing, he had a tube placed down his throat and was placed on a ventilator. He could not open his eyes without assistance.

In gathering the history, it was revealed that the man consumed home-canned corn several hours before admission. He had received it in a gift basket. The can was tested and revealed the course of the problem: foodborn botulism. A specialized blood test revealed this as well. 

Botulism is a rare and sometimes deadly illness cause by botulinum toxin, a poisonous protein caused by the bacteria, Clostridium botulinum. This powerful toxin leads to paralysis (loss of movement and/or sensation) that usually starts in the face and progresses to the arms and legs. Mr. X eventually developed  generalized weakness along with his breathing problems. When botulism comes from food, it is typically from home canning of low acidic foods. This is because Clostridium botulinum is anaerobic, which means it does not require oxygen for growth, and because it thrives in low acidic environments. Since it is common on food surfaces, it can thrive when placed inside of a can (where there is no oxygen or very little oxygen), particularly in low acidic foods such as corn, green beans, and beats.

The modern canning industry uses procedures to control the risk of botulism (e.g., pressure cooking at 121 degrees Celsius for 3 minutes, following strict hygiene) but many people who use home canning do not because they are unaware of the risks and what to do to prevent it. When consumed, signs and symptoms usually begin within 12 to 72 hours. About 24 cases of foodborn botulism occur in the U.S. per year.

So how did the story end for the 60-year-old man? Many more details are provided in the case study, but he was treated with an anti-toxin known as heptavalent botulism antitoxin (H-BAT) but his and he discharged to a long-term acute care facility after 22 days in the hospital. Because the diagnosis was not immediately determined and treatment was delayed for days, he did not receive many of the same treatment benefits that would be expected if the condition was realized sooner.

Suggested reading: Canning for a New Generation: Bold, Fresh Flavors for the Modern Pantry

Reference: Hill SE, Iqbal R, Cadiz CL, Le J. (2013). Foodborne botulism treated with heptavalent botulism antitoxin. Ann Pharmacother. 47(2) :e12.

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