Botulism is caused by botulinum toxin, a poison produced by the bacterium Clostridium botulinum.
The organism is common in the soil and can survive in this environment as a resistant spore.
C. botulinum (Photo: CDC)
There are three main types of botulism - foodborne botulism, intestinal botulism (which is due to proliferation of the organism in the gut) and wound botulism.
Symptoms often begin with blurred vision and difficulty in swallowing and speaking, but diarrhoea and vomiting can also occur. The disease can progress to paralysis. Most cases will recover, but the recovery period can be many months. The disease can be fatal in 5-10% of cases; death is due to respiratory failure.