Botulism
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Botulism

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. 



Incubation period
It is usually a matter of 12-36 hours between exposure to the toxin and the development of symptoms, though they can occur as early as 6 hourse or as late as 10 days. In infant botulism, some time may elapse between ingestion of the spores and the release of the toxin.


Symptoms

Symptoms include:
  • blurred vision
  • double vision
  • difficulty in swallowing and speaking
  • drooping eyelids
  • dry mouth
  • muscle weakness
  • sometimes diarrhoea and vomiting can occur.
  • In infants: lethargy, poor feeding, constipation, weak cry and poor muscle tone

These are all symptoms of the muscle paralysis caused by the bacterial toxin. If untreated, these symptoms may progress to cause paralysis of the respiratory muscles, arms, legs, and trunk as well as further problems with vision. Most cases make a recovery, but the recovery period can be many months. The disease can be fatal in 5-10% of cases.


Types of Botulism
There are five main kinds of botulism. The symptoms that result are not actually caused but the organism itself but by eating or breathing in the toxin which it releases:

Foodborne botulism is caused by eating foods that contain the botulinum toxin. When a person consumes the toxin it makes him ill with weakness and paralysis. Clostridium botulinum is an "anaerobic bacterium". This means that it can only grow in the absence of oxygen, so botulism in adults tends to occur when the spores have somehow got into an airtight environment such as tins or jars, particularly home-preserved foods which have been preserved in oil. The toxin is destroyed by the normal cooking processes.

Wound botulism is caused by toxin produced from a wound infected with Clostridium botulinum. It has the same symptoms as the the previously mentioned forms however it occurs when the organisms get into an open wound and so are able to reproduce in an “aerobic” environment.

Infant botulism is extremely rare and is caused when a baby consumes the spores of the botulinum bacteria. These then grow in the intestines and release toxin. In most adults and older children, this would not happen because the natural defences which have developed in an adult gut would prevent the germination and growth of Clostridium botulinum. In some babies, these defences have not yet developed, and so this gives the infection a chance to get a foothold and produce the toxin.

Adult intestinal toxemia (adult intestinal colonization) botulism is a very rare kind of botulism that occurs among adults by the same route as infant botulism.

Iatrogenic botulism can occur from accidental overdose of botulinum toxin.

All forms of botulism can be fatal and are considered medical emergencies. Foodborne botulism is a public health emergency because many people can be poisoned by eating a contaminated food.


Prevention
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. 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. 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.

Wound botulism can be prevented by promptly seeking medical care for infected wounds and by not using injectable street drugs. Most infant botulism cases cannot be prevented because the bacteria that causes this disease is in soil and dust. The bacteria can be found inside homes on floors, carpet, and countertops even after cleaning. 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.

There is a vaccine against botulism, but there are concerns about its effectiveness and it also has side effects, and so it is not widely used.


Treatment
Treatment will focus on tackling the symptoms, such as supporting ventilation in the event of respiratory failure as well as managing any paralysis. This may be required for weeks or months together with intensive medical and nursing care. The paralysis will slowly improve.

Antitoxin is available which can be given to a patient as an "antidote" to tackle the toxin. If this is given before the paralysis is complete the antitoxin can prevent worsening and shorten recovery time.

Wounds should be treated, usually surgically, to remove the source of the toxin-producing bacteria followed by administration of appropriate antibiotics. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism.​ 

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