What is Botulism?
Botulism is a rare but serious condition which develops due to toxins produced by the bacterium Clostridium botulinum. Although rare, the disease is life threatening as it paralyzes the nerves (cranial nerve palsies) and subsequently affects respiratory muscles causing respiratory arrest and even death in some cases. The bacteria are normally found in untreated water, stools, and soil. However, when the bacterial spores (inactive forms) grow in favourable conditions (eg. small intestines), they cause grave danger to the individual.
The earliest recorded history of botulism was in 1735, when the disease was found to be associated with German sausage (foodborne illness). In 1870, a German physician by the name of Muller coined the term botulism from the Latin word for sausage. Clostridium botulinum bacteria were first isolated in 1895, and the neurotoxin that it releases was isolated in 1944 by Dr. Edward Schantz.
Botulism arises due to toxins produced by the bacteria Clostridium botulinum. The bacteria produce spores or inactive forms of bacteria. Humans are infected in the following ways including
Food: When exposed to favourable conditions, the spores thrive in unhygenically manufactured foods, improperly handled food, or in food cooked at home. At home, food, such as carrot juice, cured ham and pork, oil containing chopped onions and garlic, honey, raw or smoked fish, can get contaminated.
Drugs: Individuals who inject themselves with recreational drugs, create a situation favourable to contamination with Clostridium bacteria.
Honey or Dirt: When infants have contaminated honey, use honey-contaminated pacifiers, or eat dirt, the bacterial spores reach and thrive in the small intestine.
There are five types of botulism:
- Wound botulism – In wound botulism, the Clostridium botulinum bacteria enter wounds, cuts, or injection sites. Injuries in accidents and drug injection sites are common areas of infection.
- Food-borne botulism – In this form of botulism, the bacteria enter the body through food that has not been properly fermented, stored or preserved, eg. canned food.
- Iatrogenic botulism – This toxicity arises when excess botulinum toxin is injected to treat migraines or in cosmetic surgery to treat wrinkles.
- Infant botulism – As the name suggests, this form of toxicity is observed in infants (2-8 months) who get infected from ingesting dirt or contaminated honey.
- Adult intestinal toxemia botulism – Just as in infants, this rare toxicity can arise in adults when the spores of the botulinum bacteria reach and thrive in the small intestine.
The signs and symptoms of botulism occur as nerve paralysis that sets in within a day to two days after consuming contaminated food. Sometimes, the symptoms set in quickly in 6 hours or may manifest only after 10 days. Wound injuries and infants tend to quickly get infected with the bacteria. There is no fever seen in this condition except in some cases of wound botulism.
The nerves in the eyes and face are affected by the bacterial toxin and become weak. The initial symptoms are:
- Drooping eyelids
- Blurred or double vision
- Mouth feels dry
- Vomiting, nausea, diarrhea (absent in wound infections)
Infants show the following symptoms:
- Weak crying sound
- Inability to feed well
- First signs of constipation
- Weak muscles causing floppy neck, arms, and lungs
Symptoms in advanced cases include:
- Trouble to swallow
- Breathing difficulty
- Indistinct speech
- Weak muscles and fatigue in legs and arms
The symptoms if left untreated could result in death to nearly 50% of patients. However, even with treatment, some people do not survive. In certain cases, hypotension (low blood pressure) is observed. In most cases, patients recover after a lengthy muscle paralysis and fatigue. Physical therapy helps to strengthen the muscles.
History and Physical Examination
The physician will take detailed history about food eaten in the past few days any wound sustained. He will examine the patient to assess for signs of muscle weakness such as drooping eyelids or a weak voice. However, some of the symptoms may be confused for other conditions.
The physician will recommend laboratory tests of stool and blood samples. Laboratory testing (mouse bioassay) helps to confirm the presence and type of botulinum toxin involved.
Stool and Wound Cultures:
Patient’s stool or wound cultures will help to differentiate between food poisoning caused by Cl botulinum and E coli, Salmonella spp or other Clostridium species e.g. Cl tetani. Wound culture showing Cl botulinum growth are suggestive of wound botulism.
Mouse Inoculation test:
The most definitive to confirm the diagnosis is to identify the botulinum neurotoxin in the patient's blood, serum, or stools. The patient’s sample is injected into live mice. If the sample contained neurotoxin these animals will die. At the same time mice which have been given antitoxin will survive as the toxin will become neutralized
Miscellaneous tests - to rule out similar presenting conditions include:
- Lumbar puncture: Examining the cerebrospinal fluid is usually normal except for slightly elevated proteins
- Scanning the brain – to rule out other CNS pathology
- Drug testing (Tensilon) in myasthenia gravis
- Muscle function and nerve tests (electromyogram)
There are different measures to treat botulism. If you are diagnosed with symptoms of botulism, you are admitted in the hospital for a considerable period. Treatment options include:
- Administration of antitoxin as quickly as possible to neutralize toxin
- Antibiotics – in wound botulism
- Assisted ventilation till paralyzed respiratory muscles recover
- Physiotherapy for the paralysed muscles.
In C. botulinum-contaminated wounds, the tissue is removed surgically. Vomiting drugs or enema treatment, are prescribed to remove undigested food from the stomach.
Precautions during treatment
Equine-origin botulinum antitoxin is approved to treat all forms of botulism except infant botulism. Infants are treated with the botulism immune globulin antitoxin but not antibiotics. This helps to reduce the release of toxins into the intestine when antibiotics are given.
Antibiotics are not used in cases except wound botulism as they hasten release of toxin into bloodstream.
Based on how botulism is caused, we enlist the following as risk factors:
- Non-pasteurized honey
- Improperly canned, fermented, or preserved food
- Home-cooked food
- Industrial handling of food
- Drug injections
- Medical use of botulinum toxin
- Avoid non-pasteurized honey for babies below 1 year.
- Avoid using cans with a bad smell or bulging lids.
- Consume foil-wrapped potatoes immediately or refrigerate. Do not leave baked potatoes (wrapped in foil) out at room temperature.
- Avoid eating home-cooked food that has been left out for more than 4 hours.
- Avoid stored onions or garlic in oil at room temperature.
- Boil food that has been stored, to kill any botulinum toxin that is produced.
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- Sobel J. Diagnosis and treatment of botulism: A century later, clinical suspicion remains the cornerstone. Clin Inf Dis. 2009;Vol.48(12):1674-1675.
- Botulism. Updated Oct, 2014. Accessed June 4, 2018; Cited June 4, 2018.
- Sobel J, Rao AK. Making the best of the evidence: toward national clinical guidelines for botulism. Clin Inf Dis. 2018;Vol.66(Suppl_1):S1-S3.
- Information About Botulism - (https://www.cdc.gov/botulism/testing-treatment.html)
- Nigam PK, Nigam A. BOTULINUM TOXIN. Indian Journal of Dermatology. 2010;55(1):8-14. doi:10.4103/0019-5154.60343.
- Sobel J. Botulism. Clin Inf Dis. 2005;Vol.41(8):1167-1173.>
Latest Publications and Research on Botulism
- Symptomatic treatment of botulism with a clinically approved small molecule. - Published by PubMed
- Botulism in the Pediatric Intensive Care Units in the United States: Interrogating a National Database. - Published by PubMed
- Development of An Innovative and Quick Method for the Isolation of Clostridium botulinum Strains Involved in Avian Botulism Outbreaks. - Published by PubMed
- Adult Intestinal Toxemia Botulism. - Published by PubMed