1-3 The Terrace
P.O Box 5013
Wellington
Date:
Tuesday 6th August, 2013
To:
General Practitioners, Practice Nurses, Practice Managers, Health Professionals
From:
Dr Fran McGrath, Acting Director of Public Health
Dr Pat Tuohy, Chief Advisor - Child & Youth Health
Subject:
Information on Botulism
Pages: 1 of 3
Please regularly monitor the Ministry for Primary Industries (www.mpi.govt.nz) and Ministry
of Health (www.health.govt.nz) websites for more information. Information for the public is
available on the MoH website.
Botulism is caused by the Botulinum neurotoxin (BoNT) produced by the bacteria Clostridium
botulinum. There are 7 known types of BoNT (A to G) but only subtypes A, B, E and rarely F are
known to cause disease in humans.
The neurotoxin causes illness by irreversibly binding to presynaptic cholinergic receptors at motor
nerve terminals. This leads to a disruption in the release of acetylcholine from the presynaptic
nerve that is needed to excite the muscle.
Clostridium botulinum bacteria are found throughout the environment in soil, dust and some marine
environments. Clostridium botulinum spores are occasionally found in honey.
Clinical presentation
There are four naturally occurring forms of botulism; infant, foodborne, wound, and adult intestinal
toxaemia botulism.
Classical presentation is of a person who develops acute, bilateral cranial neuropathies with
symmetrical descending weakness. Fever is usually absent, the neurologic complications are
symmetrical, the patient remains responsive, the heart rate is slow or normal, and sensory deficits
do not occur apart from blurred vision.
Infant botulism:
This more commonly affects under 6 month olds but can affect babies up to the age of 1 year.
In this situation the intestinal flora is not fully developed and the spores ingested mature and start
to release BoNT, which is absorbed by the intestine. Infant botulism may be difficult to recognise
because of its insidious onset.
Symptoms appear 3-30 days following ingestion. The sequence of symptoms and signs may vary
but prolonged constipation (usually more than 3 days and can precede weakness by several
weeks) is usually the first indication.
Subsequent symptoms and clinical signs include:

Poor feeding/weak suck

Lethargy and floppiness

Weak cry

Facial weakness

Impaired gag reflex
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Over a week these may progress to include:

Poor head control

Trouble swallowing saliva with excessive drooling

Generalised muscle weakness

Loss of ocular motility, ptosis and sluggish pupils
Difficulty breathing and respiratory difficulties are a late sign and can quickly lead to respiratory
arrest.
The condition progresses for 1-2 weeks, and then stabilises for 2-3 weeks before recovery starts
The symptoms are those of acute flaccid paralysis and have a differential diagnosis of infantile
poliomyelitis, sepsis, meningitis, encephalitis, Guillain-Barre syndrome, some metabolic disorders,
poisoning from a range of toxins, and some other neuromuscular disorders.
Foodborne botulism:
This occurs when food has not been adequately processed or stored. The Clostridium botulinum
bacteria prefer a low acid, low oxygen environment commonly found in preserved vegetables, meat
and fish. This can affect anyone who eats these products at any age. The food will not taste or look
spoiled.
In this situation the bacteria in the food produce BoNT which is directly ingested.
Symptoms occur within 12-36 hours post ingestion.
Initial symptoms include:

Nausea and vomiting

Abdominal cramps and diarrhoea
Symptoms progress and then include:

Constipation

Dry mouth

Blurred vision and diplopia

Dysphagia

Dysarthria

Hypoglossal weakness

Respiratory dysfunction that may require ventilation.

Hypothermia

Urinary retention

Loss of autonomic responsiveness to hypotension
Recovery may not begin for 100 days and may take months to resolve.
Wound botulism
This occurs when an injury is infected with C. botulinum. The bacteria produce the neurotoxin
which is absorbed through the wound.
It has a similar presentation to foodborne botulism but without the initial gastric symptoms.
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Adult Intestinal toxaemia botulism
This is similar to infant botulism but affects adults and children who have altered gastrointestinal
anatomy and microflora i.e. after intestinal surgery, inflammatory bowel disease, or congenital
abnormalities. It is related to spore ingestion.
Investigations
Take a full history including suspicious food and other people potentially infected. Consider
alternate diagnosis for acute flaccid paralysis. Take a stool sample if possible.
If the differential diagnosis suggests C. botulinum sepsis then be aware that aminoglycosides can
worsen the effects of the neurotoxin.
If there is evidence of respiratory distress emergency management and respiratory support should
not be delayed.
Discuss with your local lab and microbiologist for preferred testing methods.
Treatment
Botulism can be treated and with prompt assessment and care. The majority fully recover. All
suspected cases of botulism should be discussed with hospital specialist and microbiology/local
infectious disease specialists, and reported to the local Medical Officer of Health - suspected
botulism can be notified under the Health Act 1956 as acute flaccid paralysis (suspect polio) or
acute gastroenteritis. All cases of Acute Flaccid Paralysis should be reported to the Paediatric
Surveillance Unit in Dunedin.
Contact details for the PSU are:
Tel
3 474 7825
Fax
3 474 7817
Email nzpsu@otago.ac.nz
The affected person will be monitored and assessed and a decision will be made regarding the
appropriate use of the botulism antitoxin ‘Botulism Immune Globulin Intravenous’ (BIG-IV), Baby
BIG® for infants.
The neurotoxin effects wear off over time but the affected person may require intensive care and
ventilation during this process. Antitoxin is available overseas if required.
For more information see:
http://www.foodsafety.govt.nz/elibrary/industry/Clostridium_Botulinum-Neurotoxins_Produced.pdf
http://www.health.alberta.ca/documents/Guidelines-Botulism-2013.pdf
http://emedicine.medscape.com/article/961833-overview
CDC (US) > www.cdc.gov/nczved/divisions/dfbmd/diseases/botulism
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