​  

1. Reason for surveillance
2. Notification criteria and procedure
3. Case definitions
4. The dise​ase
5. Case management
6. Laboratory and environmental investigation
7. Contact management
8. Communication
9. Additional resources
10. References​
11. Appendices​

1. Reason for surveillance

1. To identify cases and outbreaks of botulism, and investigate the source of the botulism
2. To identify other people at risk and prevent further cases of botulism
3. To monitor epidemiology to inform development of better prevention strategies

2. Notification criteria and procedure

Botulism is to be notified to the local Public Health Unit by: 

• Treating clinicians on provisional clinical diagnosis (ideal reporting by telephone within 1 hour of provisional clinical diagnosis)
• Laboratories on microbiological or toxicological confirmation (ideal reporting by telephone within 1 hour of confirmation)

3. Case definitions

The national surveillance case d​efinition for botulism is available at Botulism Australian national notifiable diseases case definition​​​.

Case classification in the NSW Notifiable Disease Database

• Suspected cases of botulism identified by provisional clinical diagnosis should be entered into NCIMS as possible cases. 
• Cases that are found to meet the case definition after public health and clinical follow up should be classified accordingly.
• Cases that do not meet the case definition but have a clinical diagnosis of botulism by the treating clinician and plausible epidemiological evidence of source of infection should remain as possible cases.
• Cases that have been determined to have a more likely alternate diagnosis after follow-up may be excluded. 

​4. The disease​

Botulism is a rare life-threatening neuroparalytic syndrome caused by botulinum toxin.^{1, 2} 

Infectious agent

Botulinum toxin is produced by Clostridium botulinum, a bacterium that forms protective spores that can grow and produce toxin under anaerobic conditions.² There are seven types of botulinum toxin, four of which cause human botulism (types A, B, E and F).^2-4 

Reservoir

​C. botulinum is naturally present in soil and agricultural products.² Spores of C. botulinum have also been found in marine sediments and in the intestinal tracts of animals, including fish.²

Mode of transmission

The different types of botulism are defined by the specific mode of transmission. Botulism cannot be transmitted directly from person-to-person.^{4, 5} 

Foodborne botulism occurs through ingestion of food or drink contaminated with pre-formed botulinum toxin.^{1, 2, 6} Culprit foods or drinks are usually improperly processed or canned; alkaline or low acidity; stored at or above room temperature; and exposed at some stage to anaerobic conditions (e.g. home-canned or glass bottled preserved fruit/vegetables, mushrooms, aged/fermented seafood, sausage).^{1, 2, 6}

Infant botulism occurs in infants under 12 months of age due to ingestion of C. botulinum spores, followed by the germination and growth of toxin-producing C. botulinum in the immature gastrointestinal tract.⁷ An underdeveloped digestive system and microflora in infants allows spores to germinate and produce toxin after ingestion.⁸ Infant botulism has been associated with environmental exposure and the consumption of contaminated honey.^{5, 7-9} 

Wound botulism develops via secondary C. botulinum infection of contaminated wounds, when anaerobic conditions within the wound allow the bacteria to grow and produce toxin.^{1, 5} Wound botulism is often associated with exposure of wounds to soil or gravel.^{1, 5, 10} In North America and parts of Europe, wound botulism has been associated with injecting drug use linked with detections of C. botulinum in illicit drugs.^11-14 There is no evidence of C. botulinum contamination of illicit drugs in Australia, but use of injecting drugs should be considered as a possible source for wound botulism cases regardless.

Iatrogenic botulism may rarely occur due to inappropriate use of botulinum toxin containing medicines (e.g. Botox®, Dysport®, Xeomin®) for therapeutic or cosmetic purposes.¹⁵ This could include incorrect dose, unlicensed preparations, counterfeit products or other administration errors.^15-17

Inhalational botulism occurs when a person breathes in aerosolised preformed botulinum toxin, through an accidental or intentional event.¹ This has only been reported in laboratory workers but is a potential mode of transmission in a bioterrorism event.^{5, 18}

Adult intestinal botulism has a similar pathogenesis to infant botulism, but is extremely rare.¹⁹ Ingested spores germinate in the intestine and produce bacteria that reproduce in the gut and release the toxin.¹⁹ 

Persons at increased risk of disease

Children aged under 12 months are most at risk of botulism resulting from the ingestion of C. botulinum spores.⁵ Adults rarely develop botulism from the ingestion of the spores but those with inflammatory bowel disease, recent gastrointestinal surgery or anatomical bowel abnormalities are at higher risk.^{5, 19} Anyone exposed to pre-formed botulinum toxin through the ingestion of contaminated food, cosmetic or therapeutic injection or inhalation of aerosolised toxin is susceptible to infection.⁵ Reinfection has previously been reported.^{20, 21​}

Incubation period

Incubation periods vary depending on the type of botulism, as per below. Generally, the shorter the incubation period, the more severe the disease and the higher the case fatality rate.^{6, 22​}

Clinical features

While there are variations in clinical features based on the type of botulism, all forms share similar neurological manifestations caused by the action of botulinum toxin on the nervous system.³ These usually start with cranial nerve involvement, such as blurred or double vision, difficulty swallowing, and slurred speech, and progress to symmetric descending paralysis that can progress to involve the trunk, upper limbs, and lower limbs. Smooth muscle paralysis may lead to urinary retention and constipation. Death primarily results from respiratory failure due to paralysis of the diaphragm. Fever and leucocytosis are typically absent, sensory deficits do not occur, and patients remain alert.

The specific additional clinical features for each type of botulism are as follows:

Foodborne botulism: non-specific gastrointestinal symptoms are common and can occur as a prodrome or at any time throughout the illness.

Infant botulism: usually restricted to children aged less than 12 months, and typically begins with constipation followed by lethargy, weakness, poor feeding, difficulty swallowing, loss of head control and hypotonia.

Wound botulism: may include fever and leucocytosis due to concurrent infection of the wound by other bacteria. Gastrointestinal symptoms are typically absent.

Iatrogenic botulism: features depend on the dose and distribution of the toxin, with symptoms ranging from mild to severe.

Inhalational botulism: A prodrome of upper airway irritation may develop, followed by varying degrees of paralysis.

Adult intestinal botulism: presents similarly to infant botulism. It may occur in individuals who are immunocompromised, on antibiotics, or have altered bowel flora due to an anatomical or functional bowel abnormality, such as inflammatory bowel disease.  

5. ​Case management

The response to a botulism case requires close collaboration between the treating clinicians, NSW Specialist Service for High Consequence Infectious Diseases (HCID), the local PHU, and OHB.

Response times

Investigation

After notification of a suspected case, immediately begin investigation and notify OHB at nswh-onehealth@health.nsw.gov.au​​​  (during working hours) or HPNSW Medical Officer On-Call (outside of working hours). 

Data entry​​

Enter suspected cases in NCIMS within 1 working day of notification. Minimum data required for NCIMS is provided in the table below (some information may not yet be available when case is first entered and should be updated as the investigation progresses):

Case investigation

The public health investigation should focus on identifying and mitigating any ongoing risk of botulism to the public. The scope and extent of the investigation should align with the level of risk posed. Although there has been no documented large-scale, successful use of botulinum toxin in bioterrorism, the threat remains credible, and investigators should remain vigilant for any evidence of deliberate exposure. 

The PHU’s response to a notification will be in collaboration with the case’s treating clinicians, HCID and OHB. Additional stakeholders should be involved depending on the type of botulism:

OHB/HPNSW Medical Officer On-Call can facilitate the involvement of stakeholders as required. Responsibilities of PHU staff are to:

• Confirm the onset date and symptoms of the illness which may indicate the likely type of botulism
• Confirm HCID has been consulted by the treating medical team concerning testing and BAT requirement
• Seek the doctor’s permission to contact the case or relevant person responsible
• Check that the case or relevant person responsible has been informed of the suspected/confirmed diagnosis before commencing the interview
• Identify and refer the likely source to relevant stakeholders for further investigation. In investigations involving multiple stakeholders, the PHU should consider convening an IMT, led by the PHU and including representatives from OHB and other relevant stakeholders; see Appendix 3 for further details about public health unit follow-up

Exposure investigation

Cases should be interviewed using either the adult botulism (Appendix 1) or infant botulism (Appendix 2) case questionnaires. The questionnaire asks the case or case’s caregiver to recall information related to the following potential exposures in the incubation period:

• Ingestion of high-risk foods
• Traumatic or contaminated wounds
• Therapeutic or cosmetic botulinum toxin use
• Connection to any other suspected/confirmed botulism case
• Environmental exposures
• Recent history of injecting drugs

Where iatrogenic botulism is suspected, an inspection of the clinic or facility that provided botulinum toxin injections may be required. The inspection should be conducted by PHU Environmental Health Officers in collaboration with local council and Pharmaceutical Services Unit.  

Isolation and restriction

None.

Education

The case or relevant person responsible should be informed about the nature of the illness and the mode of transmission. Provide education on preventative measures to cases and caregivers. This may include:

• Foodborne botulism: proper food handling, storage and preparation. This includes taking care when undertaking home canning or other food preservation methods; and heating home-canned foods to 85^oC for 5 minutes before consumption.⁵  
• Infant botulism: avoidance of honey in infants aged less than 12 months 
• Wound botulism: wound care and prompt treatment of infected wounds 
• Iatrogenic botulism: educate on the safe and appropriate use of botulinum toxin for therapeutic or cosmetic purposes, emphasising the importance of licensed products, correct dosing, and trained practitioners.

Treatment

As botulinum toxin irreversibly binds to nerve endings, the primary aim of treatment is supportive care, including ventilatory support and intravenous fluids, until the effects of the toxin subside. An additional priority is to prevent further progression of paralysis and shorten its duration. Treatment with botulinum antitoxin (BAT) for non-infant botulism, or human-derived Botulism Immune Globulin (BabyBIG) for infant botulism, plays a crucial role in neutralising any unbound botulinum toxin. 

While laboratory confirmation of suspected cases is important, it should not delay treatment.

Botulinum Antitoxin (BAT)

​The decision to treat with botulinum antitoxin (BAT) is between the treating clinician and the NSW Specialist Service for High Consequence Infectious Diseases. When indicated, the HCID clinician will directly contact the HPNSW Medical Officer On-Call to facilitate access to BAT. 

BAT is equine-derived and licensed by the US Food and Drug Administration (USFDA) for the treatment of symptomatic botulism caused by toxins A, B, C, D, E, F, or G. It contains antibodies that neutralise circulating botulinum toxin, preventing further binding to other nerve endings. For more information on this product, see the USFDA BAT website​​.

Early administration of BAT is key to halting the progression of paralysis and is associated with decreased mortality, reduced intensive care stays, and fewer disease complications. Treatment should be considered regardless of time since onset, although BAT administration is less likely to be beneficial if symptoms have been present for more than 7 days, or if the patient has already progressed to complete paralysis. 

Botulism Immune Globulin for Infant Botulism (BabyBIG®)

Human-derived Botulism Immune Globulin (BabyBIG®) is the preferred treatment for infant botulism caused by C. botulinum toxin types A or B. Being human-derived, it is less immunogenic than equine-derived botulism antitoxin (BAT), thereby reducing the risk of anaphylaxis or lifelong sensitisation to equine proteins. Additionally, its longer half-life is better suited to the pathogenesis of infant botulism, which spans the time taken from C. botulinum spore colonisation to botulinum toxin production in the gut.

BabyBIG® is licensed by the USFDA for the treatment of infant botulism and is available exclusively through the California Department of Public Health Infant Botulism Treatment and Prevention Program.

Detailed guidance on accessing BabyBIG® is available in Appendix 4.

Antibiotic therapy

Antibiotic therapy is generally not recommended for botulism due to the theoretical risk of additional toxin release from antibiotic-mediated lysis of C. botulinum.³ 

Management of wound botulism focuses on wound debridement and administering a tetanus vaccine booster.³ Antibiotics are only required if the wound appears infected. 

Advice should be sought from infectious diseases specialists before administering antibiotics that can potentiate neuromuscular blockade, such as aminoglycosides, tetracyclines, clindamycin, and polymyxins, to treat wound or other concomitant infections.³ 

6. Laboratory and environmental investigation

Laboratory testing differs depending on the type of sample (human, food or illicit drug/injecting equipment sample), and type of botulism. Specialist advice from relevant organisations should be obtained for each case, as outlined below.

Human Samples

Collection of human samples is often not required for clinical management of a suspected botulism case. If indicated, blood and faeces should be collected from patients suspected to have botulism as soon as possible after symptoms commence. Other specimens may be collected depending on the type of botulism, e.g. tissue or exudate from a wound. Specimens should be collected before the administration of BAT.

Toxin is traditionally detected using a mouse bioassay.^{3, 10} Specimens should be transported promptly as toxin levels degrade over time. Specimens should be sent to the Institute of Clinical Pathology and Medical Research (ICPMR) at Westmead Hospital. 

PCR testing can be performed on faeces, gastric aspirate or tissue specimens but is not indicated for blood specimens. Culture methods for isolation of C. botulinum are only appropriate in the case of wound or intestinal botulism samples. 

Negative tests on clinical specimens do not necessarily exclude the diagnosis of botulism. Test results may be negative due to insufficient levels of free toxin, as only unbound toxin is detectable.³ This may occur if the toxin has already irreversibly bound to nerves or has been neutralised by antitoxin administration.³ Clinical correlation is required, and parallel testing of food and/or environmental samples may be indicated.  

Preliminary results of toxin testing generally take 24 to 48 hours. 

Food samples

The NSW Food Authority should be contacted as soon as possible to investigate suspected food sources. The NSW Food Authority will collect samples of any suspected residual food for laboratory analysis and provide other advice and actions to control any ongoing risk from contaminated food. This includes providing advice on discarding any remaining food items or contaminated utensils. The NSW Food Authority may recall suspected food products if there is a risk to the broader public.  

It is critical that the NSW Food Authority is engaged before any food sample is collected and transferred to the laboratory, as a strict chain of custody of the sample needs to be maintained. OHB will facilitate contact with the NSW Food Authority. HPNSW Medical Officer On-Call will assist after hours. 

Illicit drug samples and injecting equipment

The NSW Centre for Alcohol and Other Drugs (CAOD) should be contacted (via OHB) as soon as possible if illicit drug or injecting equipment contamination is suspected. A strict chain of custody of any sample suspected to be an illicit substance needs to be maintained and specialist drug testing will be required other than botulism testing. CAOD will facilitate sample collection and testing. Additional actions will be determined in consultation with CAOD and other relevant agencies. HPNSW Medical Officer On-Call will assist after hours.

Any potentially contaminated injecting equipment should be handled as per existing sharps procedures.

​

7. Contact management

Identification of contacts

Contacts are defined as people who may have been exposed to the same potential source. 

Investigation and treatment

In circumstances where there is a plausible risk of others being exposed to the same source, the IMT (refer to 5. Case Management) should assess the risk to contacts. Active case finding should be considered, for example by sending alerts to local hospitals to be alert for people presenting with botulism symptoms. 

For foodborne botulism, contacts confirmed to have consumed the suspected food should remain under close medical observation for 3 days. If contacts present within 6 hours of ingestion, purgative measures (e.g., gastric lavage, cathartics, or high enemas) can be considered to remove unabsorbed toxin from the gut.

For other forms of botulism (e.g. wound, iatrogenic, inhalational), advice for contacts should be tailored to the specific mode of exposure.

8. Communication

Any public communications will be coordinated by OHB, in collaboration with the PHU and other stakeholders where relevant. If risks are localised, the PHU may coordinate local communications in collaboration with OHB and other stakeholders.

Foodborne botulism

Foodborne botulinum toxin exposure may be of significant public interest, given the connection to food handling and safety in commercial settings. A thorough assessment of the exposure source should inform any communication of ongoing risk, in collaboration with the NSW Food Authority. 

Wound botulism

If wound botulism is suspected to be caused by contaminated substances in the illicit drug supply, a clinician alert or media release may need to be distributed in consultation with the CAOD. 

Iatrogenic botulism

Iatrogenic botulism may require communication of further risk to the public if there are concerns for the administration procedures of a practitioner or unregistered provider. This will be done in consultation with the expert panel and relevant stakeholders.

Inhalational botulism 

Given the rarity and urgency of the response to an inhalational botulism case, communication of further risk to public would be assessed at the time of notification. 

Infant and adult intestinal botulism

Adult intestinal and infant botulism generally pose no wider public health risk because they are both rare and have no epidemic potential. Therefore, this circumstance is unlikely to require communication of further risk to the public.