What is botulism?
Botulism is a rare but potentially fatal infection caused by toxins produced by Clostridium botulinum bacteria.
The toxins produced by C. botulinum are the most powerful naturally occurring toxins known to science. They attack the nervous system (nerves, brain and spinal cord) and cause paralysis (muscle weakness).
Left untreated, the paralysis will spread to the lungs, causing breathing failure followed by death.
It usually takes 12 to 36 hours after eating contaminated food for more serious neurological symptoms (symptoms affecting the nervous system) to begin. These include double vision, droopy eyelids and slurred speech.
Botulism is a serious condition requiring immediate medical attention. Dial 999 to request an ambulance if you, or someone you know, have the symptoms of botulism.
Read more about the symptoms of botulism.
What causes botulism?
Botulism is caused by the bacteria Clostridium botulinum, found in soil, dust and agricultural products such as honey, beans and corn.
The actual bacteria are not harmful, but if they enter your body they can produce highly poisonous toxins (poisons).
There are three main types of botulism:
- food-borne botulism: can occur when food becomes contaminated with infected soil; if the food is not properly canned, preserved or cooked, bacteria can start to produce toxins
- wound botulism: can occur when a wound becomes infected with the C. botulinum bacteria; this can be caused by injecting or sniffing drugs contaminated with the bacteria
- infant botulism: occurs when a baby ingests spores of the C. botulinum bacteria; the spores travel to the intestine where they begin to produce toxins
Read more about the causes of botulism.
Botulism is treated in hospital, although the way in which it's treated depends on the type of botulism.
Antitoxins are very effective in treating botulism, although a full recovery may take several months.
Botulism needs prompt treatment as it's life-threatening. Around 10% of people with botulism die from it.
Read more about how botulism is treated.
Due to high standards of food hygiene in the UK, the chances of getting food-borne botulism from food bought in this country are virtually nil.
There is 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.
Heroin users should avoid injecting heroin into their muscles. Injecting heroin into a vein or smoking it are safer ways of taking the drug, although not using heroin at all is by far the best course of action.
In most cases of infant botulism, the specific cause has never been identified. Therefore, it may not always be possible to prevent it.
However, avoid giving honey or corn syrup to babies under the age of 12 months because they have been known to contain bacterial spores.
Symptoms of botulism
Botulism is a serious condition that requires immediate medical attention. Dial for an ambulance if you suspect that you, or someone you know, has symptoms of botulism.
The symptoms of food-borne botulism usually begin with:
- nausea (feeling sick)
- diarrhoea, followed by constipation (an inability to empty your bowels)
It usually takes 12 to 36 hours after eating contaminated food for more serious neurological symptoms (symptoms that affect the nervous system) to begin (see below). However, it can sometimes take as little as six hours or as long as eight days.
If you have consumed (eaten or drunk) a large amount of the toxin produced by the Clostridium botulinum bacteria, you may not experience these early symptoms. Instead, you may develop neurological symptoms straight away.
Following the initial infection, symptoms of wound botulism take between 4 and 14 days to develop.
The symptoms start in the cranial nerves (nerves that connect your brain to your spine) before spreading through your body as the toxins take effect.
Neurological symptoms of food-borne botulism and wound botulism are the same. However, in cases of wound botulism, symptoms can take longer to develop.
Neurological symptoms include:
- double vision
- droopy eyelids
- facial weakness
- dry mouth
- difficulties swallowing (dysphagia)
- slurred speech
As the toxin spreads, you will have weakness and paralysis in your upper limbs. If the toxin is allowed to keep spreading, your breathing will be affected and you will eventually have respiratory failure, resulting in death.
Your sensory awareness (your awareness of the world around you) will be unaffected. There are also no symptoms of fever, such as a high temperature, during a botulism infection.
The symptoms of infant botulism usually begin with constipation. This may last for several days before the baby starts to have neurological symptoms such as:
- an inability to suck
- a floppy head
- floppy muscles
- weak crying
- poor reflexes
- heavy eyelids and flat, unfocused eyes
What causes botulism?
Botulism is caused by the Clostridium botulinum bacteria, found in soil, dust and agricultural products, such as honey, beans and corn.
The bacterium itself is not harmful, but if it enters your body it can produce highly poisonous toxins.
The Clostridium botulinum toxin is the deadliest naturally occurring poison in the world. Just 500g (1.1lb) is enough to kill every human being on the planet.
Clostridium botulinum can produce seven different types of toxin, which are classified as types A through to G. Types A, B, E and F are poisonous to humans. Type F is the most toxic. It is 60 times more poisonous than type B, which is the least toxic.
The toxins produced by Clostridium botulinum block a special type of chemical called a neurotransmitter. Neurotransmitters send messages from your brain to the rest of your nervous system (your nerves and spinal cord).
In the case of botulism, the toxin blocks the effects of a neurotransmitter called acetylcholine that your body uses to help stimulate muscles. If acetylcholine is blocked, it causes paralysis which, if left untreated, can lead to death.
Food-borne botulism can occur when food becomes contaminated with infected soil. If food is not properly canned, preserved or cooked, bacteria in the food can start producing toxins, which are highly poisonous if eaten.
Modern food production techniques use high-temperature processes that ensure all bacteria are killed.
Wound botulism occurs when a wound becomes infected with the Clostridium botulinum bacteria. This is caused by injecting or sniffing drugs contaminated with the bacteria. Once inside your body, the bacteria produce the poisonous toxins.
Most heroin users inject the drug into their veins (intravenously), but some users prefer to inject into muscles.
This may be because:
- They are trying to disguise signs of heroin injection ("track marks").
- Their veins have been damaged by previous heroin abuse.
Injecting heroin directly into muscles is dangerous because it causes tissue damage, which can lead to infection. Using clean needles and not sharing needles with others will not prevent wound botulism because it is not the needle that is infected but the heroin itself.
Most heroin in the UK comes from opium poppies grown in Asia or the Middle East, particularly Afghanistan. The opium is cooked and the morphine extracted before being treated with chemicals to produce heroin. The drugs are then "cut" with bulking materials, such as starch and lactose. The heroin can become contaminated at any point during this process.
Some cases of wound botulism have also been linked to nasal tissue damage caused by snorting cocaine. The damaged tissue can become infected. However, no cases of this kind have ever been recorded in the UK.
Infant botulism occurs when a baby ingests spores of the Clostridium botulinum bacteria. The spores make their way to the intestine (part of the digestive system) where they begin to produce toxins.
Clostridium botulinum bacteria spores are harmless to older children and adults. After about the age of one year the baby develops defences that counter the effects of the spores.
Honey and corn syrup have been known to cause some cases of infant botulism, although no definitive cause was found in the majority of cases.
Other possible causes
It is possible to be infected with the botulinum toxin in other ways. Possibilities include:
- an incorrect injection during botox: botox is a beauty treatment that uses the botulinum toxin to temporarily paralyse the facial muscles in order to reduce wrinkles
- breathing in the toxin when it is in the form of a gas; this would need to be deliberately prepared; for example, by terrorists
- drinking the toxins in water: the normal treatment process for mains water supply would de-activate the toxins, so the water would need to be deliberately contaminated; for example, by terrorists
As botulism is a serious, potentially life-threatening medical 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
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-Barré 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)
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)
Treatment for botulism will depend on the type of botulism you have, although in all cases you will need to be admitted to hospital. If botulism is not treated quickly, it is likely to be fatal.
It can take 10 days to several months for someone to recover fully from being infected with the botulinum toxin.
Food-borne and wound botulism
Treatment for food-borne and wound botulism will require immediate admission to hospital.
If you are having difficulty breathing because the toxin has spread to your lungs, you may be attached to a ventilator (a machine that helps you breathe by moving oxygen-enriched air in and out of your lungs).
You may also be given fluids and nutrients through an intravenous drip (where a tube is placed directly into a vein in your arm).
Botulism will need to be treated with injections of antitoxins. Antitoxins are antibodies (proteins produced by the body) that can neutralise a specific toxin, in this case the Clostridium botulinum toxin.
Antitoxins work by blocking the effects of the toxin on the nervous system (the nerves, brain and spinal cord).
They should be given as soon as possible. It is not necessary to wait for test results that confirm the presence of the Clostridium botulinum bacteria or toxin. A diagnosis of botulism based on your symptoms is enough to begin treatment.
An antitoxin will help prevent your symptoms from getting worse but it will not cure any paralysis (muscle weakness) already caused by the toxin. If one dose of antitoxin is not enough, you may be given a second dose after 24 hours.
In some cases of food-borne botulism, medication may be used to induce vomiting to remove all of the particles of infected food from your body.
Enemas (an injection of fluid into the large intestine) may also be used because they encourage you to empty your bowels.
If the infection has been caused by wound botulism, the infected wound and possibly a surrounding area of skin will need to be surgically removed.
The process for doing this is known as debridement. It is necessary to remove the area surrounding the wound to stop further toxins being produced. In some cases, this may lead to scarring.
You may also be given antibiotics (medicines to treat an infection caused by bacteria) to prevent any further infections developing.
Infant botulism tends to be less serious than other types of botulism because the levels of toxins released by the bacteria are lower than in other forms of the condition. However, the condition still requires emergency medical treatment to prevent breathing difficulties occurring.
Babies with infant botulism will be placed in an incubator (a clear, enclosed cot) to keep them warm and protect them from secondary infection. Artificial ventilation may be required to assist their breathing, and they may also be fed intravenously (through a tube placed directly into a vein).
Infant botulism can be successfully treated using a medicine called botulinum immunoglobulin (which has the brand name BabyBIG). Botulinum immunoglobulin is created by taking samples of human blood that contain a high level of infant botulism-immune antibodies (infection-fighting proteins.
Most babies respond quickly to treatment, and they should be well enough to leave hospital within two-and-a-half weeks. Any paralysis may last a few weeks, but babies grow new nerve endings so they should make a full recovery.
All cases of botulism must be reported to the Health Protection Agency (HPA) so that action can be taken.
There is a concern that botulism toxin could be deliberately released as an act of terrorism.
However, as the condition is very rare, a deliberate release of botulinum toxin should be easy to detect. Doctors have to report every suspected case of botulism to the Health Protection Agency (HPA).
In the event of the botulinum toxin being deliberately released, the HPA would isolate the area of exposure and provide antitoxins for anyone affected.
In the unlikely event that you are exposed to the aerosol form of the botulinum toxin (gas), cover your nose and mouth with clothing, such as a shirt or scarf. The toxin cannot penetrate unbroken skin.
Then go immediately to your nearest hospital or healthcare centre for decontamination. If this isn't possible, wash your skin and clothes with warm water and use bleach to clean any surfaces or objects that also may have been contaminated.