Botulism is a very rare but life-threatening condition caused by toxins produced by Clostridium botulinum bacteria.
These toxins are some of the most powerful known to science. They attack the nervous system (nerves, brain and spinal cord) and cause paralysis (muscle weakness).
Most people will make a full recovery with treatment, but the paralysis can spread to the muscles that control breathing if it's not treated quickly. This is fatal in around 5-10% of cases.
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Symptoms of botulism
The time it takes to develop symptoms can vary from a few hours to several days after exposure to the Clostridium botulinum bacteria or their toxins.
Without treatment, botulism eventually causes paralysis that spreads down the body from the head to the legs. Symptoms can include:
- drooping eyelids
- blurred or double vision
- facial muscle weakness
- difficulty swallowing
- slurred speech
- breathing difficulties
Affected babies may also have a weak cry, find it difficult to feed and have a floppy head, neck and limbs.
When to get medical advice
Botulism is a very serious condition that requires immediate medical attention.
Go to your nearest accident and emergency (A&E) department or dial 999 for an ambulance straight away if you or someone you know has symptoms of the condition.
Treatment is more effective the earlier it's started.
Causes and types of botulism
Clostridium botulinum bacteria are found in soil, dust, and river or sea sediments. The bacteria themselves aren't harmful, but they can produce highly poisonous toxins when deprived of oxygen - such as in closed cans or bottles, stagnant soil or mud, or occasionally the human body.
There are three main types of botulism:
- food-borne botulism - when someone eats food containing the toxins because it hasn't been properly canned, preserved or cooked
- wound botulism - when a wound becomes infected with the bacteria, usually as a result of injecting illegal drugs contaminated with the bacteria, such as heroin, into muscle rather than a vein
- infant botulism - when a baby swallows a resistant form of the bacteria, called a spore, in contaminated soil or food, such as honey. These spores are harmless to older children and adults because the body develops defences against them from about one year of age
All these types of botulism are very rare in the UK, but occasional cases do occur.
Treatment for botulism
Botulism needs to be treated in hospital.
The way it's treated depends on which type of botulism you have, but treatment will usually involve:
- neutralising the toxins with injections of special antitoxins or antibodies
- supporting the functions of the body, such as breathing, until you recover
Treatment won't reverse any paralysis that's already been caused by the toxin, but it will stop it getting any worse.
In most people, paralysis that occurred before treatment will gradually improve over the following weeks or months.
As a result of high standards of food hygiene in the UK, the chances of getting food-borne botulism from food bought in this country are tiny.
There's a slightly higher risk if you produce your own food, particularly if this involves canning. However, following food hygiene procedures and canning recommendations will reduce any risk.
You should also avoid eating food from visibly bulging or damaged cans, foul-smelling preserved foods, foods stored at the incorrect temperature and out of date foods.
Heroin users should avoid injecting heroin into their muscles. Injecting heroin into a vein or smoking it can reduce the risk of botulism, although not using heroin at all is by far the best course of action. Read more about getting help to stop using heroin.
The specific cause is not identified in many cases of infant botulism, so it may not always be possible to prevent it. However, you should avoid giving honey to babies less than 12 months old because it has been known to contain Clostridium botulinum spores.