What is botulism?
(clostridium botulinum)

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum and sometimes by strains of Clostridium butyricum and Clostridium baratii. Foodborne botulism is caused by eating foods that contain the botulinum toxin. All forms of botulism can be fatal and are considered medical emergencies. Learn more!

When people eat foods contaminated with the botulinum toxin, they can become seriously ill, or even die, if they don’t get proper medical treatment quickly.

The bacteria that make botulinum toxin are found naturally in many places, but it’s rare for them to make people sick. These bacteria make spores, which act like protective coatings. Spores help the bacteria survive in the environment, even in extreme conditions.

The spores usually do not cause people to become sick, even when they’re eaten. But under certain conditions, these spores can grow and make one of the most lethal toxins known. The conditions in which the spores can grow and make toxin are:

  • Low-oxygen or no oxygen (anaerobic) environment
  • Low acid
  • Low sugar
  • Low salt
  • A certain temperature range
  • A certain amount of water

Improperly home-canned, preserved, or fermented foods can provide the right conditions for spores to grow and make botulinum toxin. When people eat these foods, they can become seriously ill, or even die, if they don’t get proper medical treatment quickly.

There are 5 types of botulism

  • Infant botulism can happen if the spores of the bacteria get into an infant’s intestines. The spores grow and produce the toxin which causes illness.
  • Wound botulism can happen if the spores of the bacteria get into a wound and make a toxin. People who inject drugs have a greater chance of getting wound botulism. Wound botulism has also occurred in people after a traumatic injury, such as a motorcycle accident, or surgery.
  • Foodborne botulism can happen by eating foods that have been contaminated with botulinum toxin. Common sources of foodborne botulism are homemade foods that have been improperly canned, preserved, or fermented. Though uncommon, store-bought foods also can be contaminated with botulinum toxin.
  • Iatrogenic botulism can happen if too much botulinum toxin is injected for cosmetic reasons, such as for wrinkles, or medical reasons, such as for migraine headaches.
  • Adult intestinal toxemia (also known as adult intestinal colonization) botulism is a very rare kind of botulism that can happen if the spores of the bacteria get into an adult’s intestines, grow, and produce the toxin (similar to infant botulism). Although we don’t know why people get this kind of botulism, people who have serious health conditions that affect the gut may be more likely to get sick.

All kinds of botulism can be fatal and are medical emergencies. If you or someone you know has symptoms of botulism, see your doctor or go to the emergency room immediately.

signs and Symptoms of botulism. People with botulism might not have all of these symptoms at the same time.

Signs and symptoms might include:

  • Difficulty swallowing
  • Muscle weakness
  • Double vision
  • Drooping eyelids
  • Blurry vision
  • Slurred speech
  • Difficulty breathing
  • Difficulty moving the eyes

Possible signs and symptoms in foodborne botulism might also include:

  • Vomiting
  • Nausea
  • Stomach pain
  • Diarrhea

Signs and symptoms in an infant might include:

    • Constipation
    • Poor feeding
    • Drooping eyelids
    • Pupils that are slow to react to light
    • Face showing less expression than usual
    • Weak cry that sounds different than usual
    • Difficulty breathing
The symptoms of botulism all result from muscle paralysis
caused by the toxin

If untreated, the disease may progress and symptoms may worsen to cause
full paralysis of some muscles, including those used in
breathing and those in the arms, legs, and torso.

Is foodborne botulism common?

In the United States, an average of 145 cases is reported each year. Of these, approximately 15% are foodborne.

Outbreaks of foodborne botulism involving two or more persons occur most years and are usually caused by home-canned foods. Foodborne botulism is a public health emergency because many people can be poisoned by eating contaminated food.

When do symptoms appear?

In foodborne botulism, symptoms generally begin 18 to 36 hours after eating contaminated food, but they can occur as early as 6 hours or as late as 10 days.

how is botulism diagnosed?

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 including a brain scan, spinal fluid examination, nerve conduction test (EMG), or a tensilon test for myasthenia gravis may be needed to exclude these other conditions.

Tests for botulinum 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.

The paralysis slowly improves. Botulism can be treated with an antitoxin which blocks the action of toxin circulating in the blood. If given before paralysis is complete, antitoxin can prevent worsening and shorten recovery time.

Physicians may try to remove contaminated food still in the gut by inducing vomiting or by using enemas. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism.

Physicians should immediately report suspected cases of botulism to their state health department.

complications of botulism

Botulism can result in death due to respiratory failure. However, in the past 50 years the proportion of patients with botulism who die has fallen from about 50% to 3-5%.

A patient with severe botulism may require a breathing machine as well as intensive medical and nursing care for several months, and some patients die from infections or other problems related to remaining paralyzed for weeks or months.

Patients who survive an episode of botulism poisoning may have fatigue and shortness of breath for years and long-term therapy may be needed to aid recovery.

preventing botulism

Many cases of botulism are preventable.

Foodborne botulism has often been from home-canned foods with low acid content, such as asparagus, green beans, beets and corn and is caused by failure to follow proper canning methods.

However, seemingly unlikely or unusual sources are found every decade, with the common problem of improper handling during manufacture, at retail, or by consumers; some examples are chopped garlic in oil, canned cheese sauce, chile peppers, tomatoes, carrot juice, and baked potatoes wrapped in foil.

Persons who do home canning should follow strict hygienic procedures to reduce contamination of foods, and carefully follow instructions on safe home canning including the use of pressure canners/cookers as recommended through county extension services or from the US Department of Agriculture.

  • Oils infused with garlic or herbs should be refrigerated.
  • Potatoes which have been baked while wrapped in aluminum foil should be kept hot until served or refrigerated.

Because the botulinum toxin is destroyed by high temperatures, persons who eat home-canned foods should consider boiling the food for 10 minutes before eating it to ensure safety.

Honey can contain the bacteria that causes infant botulism so, children less than 12 months old should not be fed honey. Honey is safe for persons 1 year of age and older.

Preserving and Preparing food safely

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