Guidance

Botulism: clinical and public health management

Updated 18 December 2018

1. Infant botulism

Infant botulism is a rare disease that affects infants less than one year of age. C. botulinum spores from the environment or food are ingested and germinate in the infant’s large intestine and produce botulinum neurotoxin.

1.1 Clinical features

Clinical features of infant botulism include:

• constipation
• feeble cry
• poor sucking reflex
• feeding difficulties
• decreased gag reflex
• listlessness
• lethargy
• droopy eyelids
• loss of head control
• muscle weakness (arm, neck, leg)
• floppy baby syndrome

1.2 Clinical management

Prompt diagnosis and treatment with human derived Botulism immune Globulin - BabyBiG® available from the Infant Botulism Treatment and Prevention Program (IBTPP) California USA; (510) 231-7600. Successful management of infant botulism also depends on supportive care including artificial ventilation where necessary.

1.3 Laboratory diagnosis

Botulism is a clinical diagnosis and treatment with antitoxin should not be delayed for the results of laboratory investigations. Confirmation of a clinical diagnosis is by detection of botulinum toxin or isolation of C. botulinum from infant faecal specimen or rectal wash out.

Clinical specimens:

1 g (pea size) faeces or rectal wash out inoculated into cooked meat broth or other anaerobic medium for rapid PCR detection of C. botulinum and 1g faeces or rectal wash out for toxin detection.

1.4 Risk factors

Infants easily come into contact with C. botulinum spores as they are naturally present in soil and dust but infant botulism is extremely rare in the UK. It is believed that some sort of disturbance of the normal bacterial in the infant intestine provides the opportunity for C. botulinum spores, if present, to grow and produce toxin.

In most cases of infant botulism the source of spores is not identified and they are assumed to be swallowed from the environment. Windy or dusty conditions may lead to more spores being in the air.

Honey is the one food source that has been linked with infant botulism. In some honey associated cases C. botulinum spores isolated from honey consumed by the infant have been found to be the same toxin type as the C. botulinum that caused the infant’s illness.

In Argentina and some southern Mediterranean countries infant botulism has been associated with feeding infants herbal infusions or teas. There have been 2 cases of infant botulism in the UK and Ireland that have been associated with keeping terrapins as pets.

2. Foodborne botulism

Foodborne botulism is a rare disease caused by Clostridium botulinum spores germinating and growing in food and producing a very powerful neurotoxin which then gets into the body when the food is eaten. Incubation period can vary from a few hours up to 8 days but is usually within 12 to 36 hours.

Once ingested the toxin is absorbed into the bloodstream and transported to the neuromuscular junction where it inhibits release of the neurotransmitter acetylcholine, which is required for a nerve to stimulate the muscle. Botulinum toxin results in a characteristic descending symmetrical flaccid paralysis.

Foodborne botulism is considered a public health emergency because contaminated food may be available to other persons.

2.1 Clinical features

Botulism is characterised by an acute afebrile descending symmetrical paralysis. In food borne botulism gastrointestinal symptoms such as nausea, vomiting, diarrhoea, may precede neurological symptoms but are not always present.

Neurological symptoms include:

• disturbances to vision: blurred vision, double vision, drooping eyelids, dilated pupils
• difficulty in swallowing and talking: slurred speech, dry mouth
• descending muscle weakness
• respiratory difficulty or failure due to respiratory muscle paralysis

2.2 Clinical management

Prompt diagnosis and treatment with botulinum antitoxin to neutralise circulating toxin, together with supportive therapy and symptomatic treatment. Intubation and mechanical ventilation may be required in severe cases. Recovery can take several weeks.

2.3 Laboratory diagnosis

Botulism is a clinical diagnosis and treatment with antitoxin should not be delayed for the results of laboratory investigations. Confirmation of a clinical diagnosis is by detection of botulinum toxin in serum or faecal specimens or detection and isolation of C. botulinum from faeces or food samples.

Clinical specimens:

10 ml serum taken prior to antitoxin treatment

10g faeces or rectal wash out for toxin detection and a pea sized portion inoculated into cooked meat broth for rapid PCR detection of C. botulinum

Food samples:

10g portion of suspected food to be sent refrigerated

2.4 Risk factors

Food borne botulism is usually caused by a fault during food processing or storage which enables C. botulinum to grow and produce toxin in food. Spores of C. botulinum are widely distributed in the environment and may be present in food but do not usually pose a threat as they are unable to grow as they require certain conditions to do so, including the absence of oxygen. However, if the right conditions do exist, the spores can germinate, grow and produce toxin.

Foods that have been associated with foodborne botulism include home preserved foods, tinned and bottled foods, foods preserved in oil and food packed in airtight containers. Although most cases of foodborne botulism are caused by home preserved foods there have been rare incidents involving commercially prepared food. Botulinum neurotoxin is heat labile and destroyed by normal cooking procedures.

3. Wound botulism cases associated with injecting drug use

In recent years we have seen an average of 2 reports of probable or confirmed cases of wound botulism per year among people who inject drugs in England. Reported cases of wound botulism associated with injecting drug use are published in the ‘Shooting Up’ report.

3.1 Clinical features

The main clinical syndrome produced by botulinum toxin is an afebrile, descending, flaccid paralysis. Patients with botulism typically present with difficulty speaking, seeing and/or swallowing. They may have double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, and muscle weakness. If untreated, paralysis may progress to the arms, legs, trunk and respiratory muscles.

There is usually no fever, no loss of sensation and no loss of awareness. There may also be autonomic signs with dry mouth, fixed or dilated pupils, and cardiovascular, gastrointestinal and urinary autonomic dysfunction. If onset is very rapid, there may be no symptoms before sudden respiratory paralysis occurs, which may be fatal. Recovery can take months. Clinicians should suspect botulism in any patient with an afebrile, descending, flaccid paralysis.

3.2 Laboratory diagnosis

Confirmation of the clinical diagnosis is by the demonstration of botulinum toxin in blood samples or, in the case of wound botulism, by the identification of C. botulinum in wound specimens. Routine laboratory tests are not helpful and specimens should therefore be sent immediately to the reference laboratory.

Samples to be taken from acutely ill patients include:

• serum: At least 10ml. Serum samples must be collected before antitoxin is administered.
• wound. Pus: As much as possible in a sterile container. If pus is not available, a swab of the lesion should be taken and put immediately into a transport medium for anaerobic culture.
• biopsy tissues: If surgical debridement is performed, biopsy tissues should be placed immediately into a sterile container.
• post mortem specimens: Heart blood (10ml), if not haemolysed, should be sent for serum for serum collection. Specimens from infected wounds may also be useful

All samples must be kept refrigerated after collection.

All specimens should be sent directly to the Gastrointestinal Bacteria Reference Unit with the sender’s name and address clearly marked. The reference laboratory should be telephoned prior to sending the sample.

Out of office hours, laboratory personnel can be contacted through the Public Health England (PHE) duty doctor on 0208 200 4400.

3.3 Clinical management

Botulinum antitoxin is effective in reducing the severity of symptoms if administered early in the course of the disease. C. botulinum is sensitive to benzyl penicillin and metronidazole. In cases of wound infection, antimicrobial therapy and surgical debridement should reduce the organism load and therefore toxin production, but circulating toxin can only be neutralised by the early administration of antitoxin.

Where there is definite clinical suspicion of botulism, treatment with antitoxin should not be delayed for microbiological testing.

Antitoxin can be obtained from the Colindale site by contacting the duty doctor on 020 8200 4400.

3.4 Preventive measures

The risk of death in individuals presenting with wound botulism may be reduced if supportive therapy and antitoxin are provided promptly. Increased awareness amongst clinicians may facilitate prompt diagnosis and treatment.

Wound botulism is thought to occur in people who inject drugs when heroin contaminated with C. botulinum spores is injected into sites that encourage anaerobic conditions. There is no way of telling if a supply of heroin (or other drugs) is contaminated with C. botulinum spores. The following advice may reduce the risk of wound botulism in people who inject drugs:

Smoking heroin instead of injecting may reduce the risk of wound botulism. However, some infections, such as anthrax, can result from smoking contaminated heroin. Overall smoking heroin is likely to be safer than injecting, but there are still risks.

PHE advice for ‘Botulism infection in those who inject drugs’ is available on the PHE website.

4. Reporting and public health investigation

Since food borne botulism constitutes a public health emergency, food must be excluded as a source for all cases of botulism. PHE has prepared a botulism reporting questionnaire that consultants in communicable disease control (CCDCs) can use to obtain information on clinical presentation, food history and injecting behaviour from all suspected cases of botulism.

Food samples associated with suspected cases of food borne botulism must be obtained as a matter of extreme urgency in order to prevent further cases.

Samples of heroin can be tested by PHE for the presence of microbial contamination.

If the police are in possession of drugs believed to be associated with suspected cases of wound botulism, please contact PHE foodborne pathogens reference services (part of the gastrointestinal bacteria reference unit) on 020 8200 4400 ext 7117 to discuss arrangements for testing.

Clinicians and CCDCs are asked to report any suspected cases of botulism to PHE foodborne pathogens reference services or to the PHE duty doctor on 020 8200 4400.