Botulism - Diagnosis 

As botulism is a serious, potentially life-threatening condition, it is usually diagnosed following admission to hospital.

After someone has been admitted to hospital, doctors might suspect botulism based on the following criteria:

• where there is paralysis, such as double vision, difficulty swallowing and slurred speech
• the lack of a fever (high temperature)
• the person's awareness of the world around them being unaffected

Testing

As botulism is such a rare condition, other tests will usually be performed to rule out conditions with similar symptoms such as:

• a stroke - a serious medical condition where the blood supply to the brain is interrupted
• being poisoned with something else, such as carbon monoxide poisoning or food poisoning from shellfish 
• Guillain-Barre syndrome - a rare but serious condition that affects the network of nerves that control the body's movements and senses

Tests you may have include:

• a magnetic resonance imaging (MRI) scan - where a strong magnetic field and radio waves are used to produce detailed images of the inside of your body
• a computerised tomography (CT) scan - where a series of X-rays of your body are taken at slightly different angles and a computer puts the images together
• a lumbar puncture (spinal tap) - where a hollow needle is inserted into your lower back to extract a sample of cerebrospinal fluid (the fluid that surrounds and protects your spine)

Confirmation

To confirm a diagnosis of botulism, tests will be carried out to detect the Clostridium botulinum bacteria or the toxin produced by the bacteria. Depending on which type of botulism you have, this may be found in a sample of:

• your blood
• your faeces (stools)
• the contents of your stomach (for food-borne botulism)
• pus or tissue from a wound (for wound botulism)
• the contaminated food, if you still have some left (for food-borne botulism)