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Botulism (Potential Bioterrorism Agent)

Queensland Health Guidelines for Public Health Units

Revision History

1.0September 2010Full revision of guideline
2.0July 2014Full revision of guideline
3.0June 2016Full revision of guideline

Infectious Agent

Clostridium botulinum is a spore-forming anaerobic bacillus. Botulism is caused by the neurotoxins produced by Clostridium botulinum. Of the recognised subtypes of neurotoxin, types A, B, E, rarely F and possibly G cause human illness.

Notification Criteria

The case should be reported to the Public Health Unit if there is clinical evidence regardless of whether there is laboratory definitive evidence for botulism or if identified as a case of acute flaccid paralysis

Clinical evidence

A clinically compatible illness (eg. diplopia, blurred vision, muscle weakness, paralysis, death, or constipation poor feeding, difficulty swallowing, an altered cry, loss of head control and hypotonia in infant botulism).

Laboratory definitive evidence

1.    Isolation of Clostridium botulinum in a clinical sample
2.    Detection of Clostridium botulinum toxin in blood or faeces.

Community Outbreak Criteria    

1.    Two or more associated confirmed cases (confirmed outbreak)
2.    Two or more associated suspected cases OR one confirmed case and one associated suspected case (suspected outbreak).

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Notification Procedure

Pathology Laboratories
To notify (i) on receipt of request for examination (except for wound botulism) and (ii) on microbiological or toxicological confirmation, by telephone or facsimile.

Attending Medical Practitioners/Medical Superintendents (or Delegates)
To notify all cases of acute flaccid paralysis on clinical diagnosis by telephone or facsimile.

C. botulinum is a ‘prescribed contaminant’ under the Food Act 2006 and Food Regulation 2006[1]. This means that if it is identified in food intended to be sold it must be immediately notified verbally to the chief executive of Queensland Health and reported in writing (using the approved form) within 24 hours by the person who has identified the contaminant and/or the person who was intending to sell the food.

Laboratory Aspects

Laboratory tests include detection of neurotoxin in clinical and food samples, detection of the organism and isolation from clinical and food samples.
The specimens required depend on the clinical presentation and include[2]

Foodborne botulismWound botulismInfant botulism
15 - 20ml+ serum* taken prior to antitoxin treatment15 ml serum* taken prior to antitoxin treatment2mL of serum should be obtained from infants and as much faeces as possible.
Faeces (25-50g)* or high rectal washout and 1g inoculated into Cooked Meat Broth and other anaerobic mediumPus from wound/abscess or debrided tissue in Cooked Meat Broth and other anaerobic mediumFaeces (25-50g) or rectal wash out* in Cooked Meat Broth and other anaerobic medium
Vomitus, gastric contents, intestinal contents if available (100) Vomitus, gastric contents, intestinal contents if available
Food items implicated (200g+) Food items implicated e.g. honey, formula milk (200g)

The gold standard test for botulinum is the mouse bioassay, which tests for A, B, E and F toxin subtypes[3]. A positive result will usually be available within 24 – 48 hours of receipt of the specimen at Queensland Health Forensic and Scientific Services. For faeces samples, this is then confirmed by PCR. 

* Blood and faeces should be collected from the patient as soon as possible after the onset of symptoms. It is preferable to collect blood (and faeces if possible) before administration of antitoxin. Blood is drawn into a plain specimen tube without anticoagulant. Ideally, 15-20mL serum and 25-50g faeces should be collected. 2mL of serum should be obtained from infants and as much faeces as possible[4]. Faecal sampling is important for the detection of C. botulinum and toxin as positive food samples may not be available

Reporting to NOCS

Only confirmed cases should be reported. 

Confirmed case
A confirmed case requires laboratory definitive evidence AND clinical evidence.

Suspected case
A suspected case requires clinical evidence only.

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Objectives of Surveillance

1. To monitor the epidemiology of botulism in Queensland to inform preventive strategies.
2. To identify cases, outbreaks and implicated food sources to enable prompt public health response

Public Health Significance and Occurrence

Botulism occurs worldwide. It is a rare but serious intoxication resulting from exposure to the toxins produced by C. botulinum.  Exposure may occur via ingestion, inhalation or percutaneously through a break in the skin, giving rise to the different forms of botulism. These are: foodborne (classical); intestinal (infant); wound; and inhalation.  The intestinal form is the most common and usually affects infants under 1 year, but can affect adults with altered GI anatomy and microflora and/or who are immunocompromised. In both the intestinal and wound form, the bacteria enter the body, multiply, and then release toxin.  In the foodborne and inhalational forms, toxin itself enters the body. The disease is highly lethal without treatment. With intensive therapy, mortality should be less than 5% but recovery may take months.

Twenty-four cases of botulism were reported in Australia between 1991 and 2015.
Botulinum toxin is a potential bioterrorism agent. Although the greatest threat may be by aerosol use, the more likely threat may be via the deliberate contamination of food or drink. When responding to a case, investigators should be mindful of the possibility of deliberate intoxication.

Clinical Features

A neuroparalytic progressive disorder, clinical features are similar across the different forms[5,6,7].

  • Foodborne
Early symptoms are often marked fatigue, weakness, and vertigo.  Blurred vision, dry mouth and difficulty swallowing follow as the cranial nerves become involved. Flaccid paralysis continues, symmetrical and descending.  There is no fever and no loss of consciousness.  Paralysis of respiratory muscles can cause respiratory arrest and death without mechanical ventilation. Most cases recover, if diagnosed and treated promptly. Recovery may take months.
  • Intestinal botulism
This form usually occurs in infants <1 year old and typically begins with constipation.  Other symptoms include: poor feeding, difficulty swallowing, an altered cry, loss of head control and hypotonia.  Illness ranges from mild with gradual onset to sudden infant death. An adult form occurs rarely in immunocompromised patients and is associated with altered bowel flora from antimicrobial use or in those with anatomical or functional bowel abnormality.
  • Wound botulism
A rare disease, normally associated with severe trauma, it occurs when spores get into an open wound and reproduce in an anaerobic environment. Symptoms are similar to the foodborne form, but may take up to 2 weeks to appear.
  • Inhalational botulism
Has only been reported in laboratory workers. In these cases, neurological symptoms were the same as in foodborne botulism, but the incubation period was longer. All affected people recovered within 2 weeks after antitoxin treatment. Studies suggest that following inhalational exposure, there would be an irritant upper airway prodrome followed by variable onset of different degrees of paralysis in different people.
  • Iatrogenic botulism
Recommended doses of botulinum toxin used for use in cosmetic and medical treatments are too low to cause systemic disease. However, injection of high doses of an unapproved botulinum toxin may result in severe adverse events. Clinical manifestations are similar to other forms of botulism, with symmetrical cranial nerve palsies followed by descending, symmetric flaccid paralysis of voluntary muscles, which may progress to respiratory compromise and death.

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Sources and reservoirs for Clostridia spores include soil, mud, water, and the intestinal tracts of animals[8]. In humans, contaminated food items associated with botulinum toxin include[9]:

  • For infants: Honey, home-canned vegetables and fruits, corn syrup.
  • For children and adults: Home-canned foods with a low acid content, improperly canned commercial foods, home-canned or fermented fish, herb-infused oils, baked potatoes in aluminium foil, cheese sauce, bottled garlic, foods held warm for extended periods of time.
These spores, which are very resistant to a number of environmental stresses such as heat and high acid, can become activated in anaerobic environments, low acidity (pH greater than 4.6), high moisture content, and in temperatures ranging from 3°C to 43°C. In hostile environmental conditions, the heat-resistant spores enable the bacteria to survive in a dormant state until conditions become more favourable.

Mode of Transmission

  • Ingestion of toxin-contaminated food which was not adequately cooked prior to consumption eg. improperly canned or preserved food consumed without further/adequate heating.
  • Ingestion of C. botulinum spores, colonisation of the gut with the organism and subsequent production of toxins. Sources of the spores include foods and dust.
  • Wound contamination (under anaerobic conditions) - usually via soil or gravel, but also occurs in injecting drug users. C. botulinum spores germinate and produce toxin in the wound.
  • Inhalation of aerosolised toxin in a deliberate release or laboratory accident.
  • There is no evidence of person-to-person transmission.

Incubation Period

Food-borneWithin 12 - 72 hours (range 2 hours to 8 days) after exposure.  In general, the shorter the incubation period the more severe the disease and the higher the case fatality rate[5]
IntestinalUnknown, (it is difficult to know when the spores were ingested)
Wound4 - 15 days[5]
InhalationalThought to be 12-80 hours (range 2 hours to 8 days) after exposure[7]

Period of Communicability

Despite the excretion of organisms in the faeces of intestinal botulism patients for weeks to months after onset of illness, no instance of secondary person-to-person transmission has been documented. Foodborne botulism patients typically excrete the toxin for shorter periods.

Susceptibility and Resistance

Everyone is susceptible to intoxication. Intestinal botulism is almost always in infants <12 months of age.

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  • Investigate all notifications of testing request to ascertain whether there is a clinically compatible illness.
  • If suspected case facilitate testing and notify CDB
  • For suspected and confirmed cases try to identify the source of toxin and identify others who may have been exposed to it.
  • Complete either the adult or child botulism CRF and email/fax a copy to OzFoodNet, CDB.

  • Foodborne, inhalation, intestinal and wound botulism: supportive treatment with access to intensive care management, and antitoxin
  • In addition for wound botulism surgical treatment of contaminated wound, and appropriate antibiotics to prevent/manage secondary infections may also be considered
Antibiotics do not improve the course of the disease; aminoglycoside antibiotics may synergistically exacerbate the neuromuscular blockade.
Antitoxins are discussed in further detail below, Botulism antitoxin.


The case should be advised of the nature of the infection and its mode of transmission. Specific advice should be given if home food canning is implicated.

Botulism Antitoxin

Human derived antitoxin (BabyBIG), is no longer produced in the USA and is unavailable in Australia.

Only Equine derived heptavalent botulism antitoxin (heptavalent BAT) is available, in limited supply, in Australia for the treatment of infants, children and adults.

Equine derived BAT has long been used in the treatment of botulism in adults. Currently the efficacy of heptavalent BAT has not established in paediatrics and limited safety data are available, see product information. However given this is the only form of BAT available in Australia, as part of the National Medical Stockpile, this guideline recommends the use of heptavalent BAT in infants, children and adults in line with manufacturer’s instructions. The use of heptavalent BAT is governed by the TGA Special Access Scheme.

Treatment with heptavalent BAT will not reverse paralysis, but will help stop disease progression.  Early treatment in adults has been shown to reduce length of time in intensive care and duration of mechanical ventilation as well as overall length of hospital stay.

Heptavalent BAT is for administration to individuals on the slightest suspicion of botulism. Under no circumstances should the treatment be delayed whilst waiting for the results of laboratory investigations and clinical observations.

Vials come in variable sizes and fill volumes but contain the equivalent minimum antitoxin potency, see heptavalent BAT product information sheet[10].

The process for obtaining heptavalent BAT is to contact the local Public Health Physician who will facilitate access via the Queensland Health Central Pharmacy, see heptavalent BAT access protocol.

An intravenous heptavalent form of equine antitoxin [Botulism Antitoxin heptavalent (A,B,C,D,E,F,G) – Equine, Cangene Corp, Canada] has recently been approved by the FDA in the United States. It is indicated for the treatment of symptomatic botulism following documented or suspected exposure to botulinum neurotoxin serotypes A, B, C, D, E ,F, or G in adults and paediatric patients.


The Australian Immunisation Handbook (10th edition)[11] states that hypersensitivity, presenting as fever, serum sickness or anaphylaxis, may follow its use. Patients with a history of hypersensitivity to horses or equine blood products, asthma, and hay fever are at a greater risk for developing severe hypersensitivity reactions to heptavalent BAT. To ascertain risk of allergic reactions in these cases, consider performing a skin sensitivity test according to the manufacturer’s instructions.

There are a range of warnings and precautions in the Product Information relating to hypersensitivity reactions, delayed allergic reactions (serum sickness), infusion reactions and interference with blood glucose testing.

There are no contraindications for use of heptavalent BAT.


Contact Tracing      
Yes - where food-borne or inhalational botulism is suspected or confirmed.

Persons who are known to have eaten incriminated food or been exposed to the same laboratory/inhalational incident.

Identify contacts and obtain further details e.g. on food histories and symptoms.  Recover and test suspected food sources where possible.

For contacts of a food-borne case, assess the level of risk, and consider purgative treatment (cathartics, gastric lavage, high enemas etc.,) for those who have eaten incriminated food, if they are still within the incubation period.

Administration of (equine) antitoxin to asymptomatic individuals should be considered carefully i.e. potential protection if given in the first 1–2 days after ingestion versus risk of sensitisation and reactions to horse serum.

The contact should be advised of the nature of the infection and its mode of transmission.  
Specific advice should be given if home food canning is implicated.

Other control measures

  • After exposure to aerosolised toxin, clothing and skin should be washed with soap and water.
  • Any food implicated by the case should be detoxified by boiling before discarding, or break the containers and bury them deeply in soil.
  • Contaminated utensils should be cleaned by boiling or with bleach.
  • Other contaminated objects should be cleaned with bleach.
Community outbreaks
  • Establish local or statewide outbreak control team.
  • Facilitate testing of suspected cases
  • Look for common source.
  • If the outbreak is suspected to be foodborne, refer to the Foodborne Illness Outbreak Management Guidelines– 2006[12] at:

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Preventive Measures

  • Effective control of processing and preparation of commercially canned and preserved foods.
  • Educate people concerned with home canning and other food preservation techniques, about cooking time, pressure, temperature, adequate refrigeration, storage etc.
  • Be aware that C. botulinum may or may not cause container lids to bulge and the contents to have ‘off odours’.
  • Food should be heated adequately before serving. An internal temperature of 85 degrees Celsius for at least 5 minutes will detoxify contaminated food or drink.
  • Do not feed identified sources of C. botulinum spores, such as honey, to infants under 12 months of age.
  • Recall any implicated food product immediately.
  • Toxoid vaccines are used in the USA and in Japan for at-risk workers including military personnel. Recombinant vaccines are in development.


Prepare a report of any investigation for the Communicable Diseases Unit, Queensland Health, on request (and for OzFoodNet if foodborne).


1.    Queensland Government, 2006, Food Act and Food Standards Code, cited 20 April 2016, Available

2.    PHLN, 2006, Botulism Laboratory Case Definition; BC Centre for Disease Control July 2015, Management of specific diseases, Botulism.

3.    Ferreira, J. L., S. Maslanka, E. Johnson, and M. Goodnough. 2003, Detection of botulinal neurotoxins A, B, E, and F by amplified enzyme-linked immunosorbent assay. J. AOAC Int. 86:314-33

4.    Department of Health, 2007, Botulism Laboratory Case Definition, PHLN, viewed 20 April 2016, available

5.    Heymann D (ed), 2015, Control of Communicable Diseases Manual, 20th edition.  American Public Health Association: Washington.

6.    Sobel, J., 2005, Botulism. Clinical Infectious Diseases, 41(8), pp.1167-1173.

7.    Bennett, J.E., Dolin, R. and Blaser, M.J., 2014, Principles and practice of infectious diseases. Elsevier Health Sciences.

8.    Klaassen, Curtis D., Editor, 2008, Casarett and Doull’s Toxicology: The Basic Science of Poisons. 7th Edition, New York: McGraw-Hill Companies, Inc.

9.    U.S. Department of Health & Human Services, FoodSafety - Botulism, viewed 20 April 2016, available

10.    Cagene Corporation, 2013, BAT [Botulism Antitoxin Heptavalent (A, B, C, D, E, F, G) – (Equine)], viewed 20 April 2016, available

11.    NHMRC, 2013, The Australian Immunisation Handbook, 10th edition. NHMRC: Canberra.

12.    Queensland Health, 2006, Foodborne Illness Outbreak Management Guidelines, viewed 20 April 2016, available

Last updated: 10 August 2017