Botulism

What is botulism?

Botulism is a serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. The bacteria may enter the body by ingestion of improperly canned or preserved food or through wounds.

What are the causes?

Clostridium is found in soil and untreated water throughout the world. It produces spores that survive in improperly preserved or canned food, where they produce toxin. When eaten, even minute amounts of this toxin can lead to severe poisoning. The foods most commonly contaminated are home-canned vegetables, pork, smoked or raw fish, and honey. Botulism may also occur if the organism enters open wounds and produces toxin there.

There are three main kinds of botulism:

1. Foodborne botulism is caused by eating foods that contain the botulism toxin.
   
2. Wound botulism is caused by toxin produced from a wound infected with Clostridium botulinum.
   
3. Infant botulism is caused by consuming the spores of the botulinum bacteria, which then grow in the intestines and release toxin. The most common cause of infant botulism is from the ingestion of honey. Clostridium also occurs normally in the stool of some infants.
   
   All forms of botulism can be fatal and are considered medical emergencies. Foodborne botulism can be especially dangerous because many people can be poisoned by eating contaminated food.

What are the symptoms?

• difficulty swallowing and speaking
  
• progressive weakness with paralysis
  
• nausea, vomiting
  
• abdominal cramps
  
• dry mouth
  
• double vision
  
• breathing difficulty that may lead to respiratory failure
  no fever, usually

In infants: constipation, weakness, loss of muscle tone, weak cry, poor feeding and weak sucking, respiratory distress may occur.
Symptoms usually appear between 8 to 36 hours after consuming contaminated food, but they can occur as early as 6 hours or as late as 10 days.

How is it diagnosed?

The tests may include a brain scan, spinal fluid examination, nerve conduction test (electromyography, or EMG), and a tensilon test for myasthenia gravis. The most direct way to confirm the diagnosis is to demonstrate the botulinum toxin in the patient's serum or stool by injecting serum or stool into mice and looking for signs of botulism. The bacteria can also be isolated from the stool of persons with foodborne and infant botulism.

What is the treatment?

The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks, in addition to intensive medical and nursing care. After several weeks, the paralysis slowly improves. If diagnosed early, foodborne and wound botulism can be treated with an antitoxin blocks that the action of toxin circulating in the blood. This can prevent patients from worsening, but recovery still takes many weeks. Physicians may try to remove contaminated food still in the gut by inducing vomiting or by using enemas. Wounds should be treated, usually surgically, to remove the source of the toxin-producing bacteria. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism. Currently, antitoxin is not routinely given for treatment of infant botulism.

What is the prognosis?

Prompt treatment significantly reduces the risk of death.

What are the complications?

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 significantly. A patient with severe botulism may require a breathing machine as well as intensive medical and nursing care for several 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.

What is the prevention?

Botulism can be prevented. Foodborne botulism has often been from home-canned foods with low acid content, such green beans, beets and corn. However, outbreaks of botulism from more unusual sources such as chopped garlic in oil, peppers, tomatoes, improperly handled baked potatoes wrapped in aluminum foil, and home-canned or fermented fish. 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 botulism 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. Because honey can contain spores of Clostridium botulinum and this has been a source of infection for infants, children less than 12 months old should not be fed honey. Honey is safe for persons 1 year of age and older. Wound botulism can be prevented by promptly seeking medical care for infected wounds and by not using injectable drugs.