What are the Causes of Botulism?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.
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.
What are the Five Types of Botulism?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.
What are the Symptoms and Signs of Botulism?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)
- Weak crying sound
- Inability to feed well
- First signs of constipation
- Weak muscles causing floppy neck, arms, and lungs
- Trouble to swallow
- Breathing difficulty
- Indistinct speech
- Weak muscles and fatigue in legs and arms
How can you Diagnosis of Botulism?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 eg 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)
How do you Treat Botulism?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.
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.
What are the Risk Factors of Botulism?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
How can you Prevent Botulism?
- 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.
- About Botulism - (https://www.mayoclinic.org/diseases-conditions/botulism/symptoms-causes/syc-20370262)
- What is Botulism? - (https://medlineplus.gov/ency/article/000598.htm)
- 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 BotulismA pragmatic harm reduction approach to manage a large outbreak of wound botulism in people who inject drugs, Scotland 2015. - Published by PubMed
Is black tar heroin use associated with wound botulism? A report of two Hispanic patients. - Published by PubMed