Clinical features

Symptoms occur 18 to 36 hours after ingestion of the toxin.

Possible gastrointestinal symptoms include constipation - most frequent in infants (1) - and gastroenteritis - diarrhoea, cramps, vomiting. Fever is not associated with botulism.

Visual paralytic symptoms occur first - pupillary dilatation, blurred vision, diplopia, ptosis - and are followed by a general extreme fatiguability with severe weakness of the limbs and bulbar muscles. The voice changes.

On examination, tendon reflexes are usually preserved and usually there is no sensory disturbance or alteration of level of consciousness.

A milder condition occurs in infants and is associated with colonisation of the bowel by the organism.

Notes (1):

• characteristic symmetric descending flaccid paralysis of motor and autonomic nerves: slurred speech, double vision, difficulty in swallowing, ptosis, respiratory muscle paralysis
  • in food botulism, diarrhoea and vomiting may precede neurological symptoms by a few hours
  • in infants, constipation is a frequent, often over-looked symptom

Reference:

• PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections