Botulism

Botulism is a rare poisoning caused by a toxin made by the bacterium Clostridium botulinum. The danger is not the bacterium itself but its toxin: it cuts the line between nerve and muscle, and the muscles stop obeying. The weakness travels downwards, starting with the eyes, the face and the throat, and it can reach the muscles that let you breathe. That is why this is counted in hours. With treatment started in time most people recover completely, although recovery takes weeks and months. Botulism does not pass from person to person.

What happens inside

The bacteria themselves live in soil, in river and sea sediment and in dust, and there they bother nobody. They only start producing the toxin where there is no oxygen and it is warm enough: in a sealed jar, in a tightly packed container of preserves, deep inside a wound and sometimes in the gut of a baby.

Once in the bloodstream, the toxin reaches the nerve endings and blocks the release of the substance that tells a muscle to contract. The nerve is intact, the muscle is intact, but the instruction never arrives. Two important consequences follow. Consciousness stays clear and sensation is unaffected, so the person understands and feels everything but cannot lift their eyelids or swallow. And to recover, the body has to grow fresh nerve endings to replace the blocked ones, which is not a quick business.

Where the toxin comes from

• From food. The best known route. Home preserves of mushrooms, vegetables, meat or fish; cured and lightly salted fish; vacuum-packed smoked foods kept somewhere warm. Less often, potatoes baked in foil or garlic in oil left standing at room temperature.
• Through a wound. Bacteria get into a deep, dirty wound and make the toxin on the spot. A separate risk group is injecting drugs under the skin or into muscle.
• In babies. Under the age of one the gut cannot yet keep spores in check and they germinate inside. The clearest known source is honey, and less often household dust and soil. In older children and adults the same spores are harmless.
• After botulinum toxin injections. The same poison in minute doses is used in cosmetic work and in neurology. If the product is unlicensed, the dose too high, or the person injecting untrained, the effect can spread well beyond the intended muscle.

The first signs and how it unfolds

From the toxin getting in to the first symptoms usually takes anywhere from a few hours to two days, occasionally up to a week. The shorter that interval, the more severe the illness tends to be.

Foodborne botulism often begins with nausea, vomiting, stomach pain, diarrhoea or, conversely, constipation, and at that stage it is easily mistaken for ordinary food poisoning. After that it becomes obvious that it is not:

• double vision, blurring, difficulty reading;
• drooping eyelids and a face with little expression;
• a dry mouth that drinking does not relieve;
• slurred speech, a quieter and more nasal voice;
• trouble swallowing, with food and drink going down the wrong way;
• weakness in the arms, then in the trunk and legs;
• shortness of breath and shallow breathing.

There is usually no fever, and that is an important distinguishing feature. In a baby the picture is different: first constipation lasting several days, then feeble feeding, a weak cry, and the child stops holding their head up and goes floppy in your arms.

When waiting is not an option

Call the emergency services at once if, after a questionable meal or with a wound present, someone develops double vision, drooping eyelids, slurred speech, difficulty swallowing or shortness of breath. The same applies if a baby becomes floppy, feeds poorly and cannot hold their head up.

Do not wait for things to "become clearer". The medicine that neutralises the toxin works better the earlier it is given: it binds the poison still circulating in the blood, but it does not unblock nerves that are already affected. Every hour of delay is a share of the paralysis that will then take months to grow back. If you ate the suspect food with other people, say so, because they need examining too even if they feel fine so far. Do not throw away what is left of the food: it will be needed for testing.

What it gets mistaken for

Botulism is rare and most doctors see it seldom. Similar weakness occurs in Guillain-Barré syndrome, in myasthenia, in a stroke affecting the brainstem, and in poisoning by certain mushrooms and medicines. Botulism is recognised by the combination: the paralysis is symmetrical, it moves strictly from head downwards, there is no fever, no loss of sensation, consciousness is preserved, and the pupils are often wide and sluggish in the light.

Laboratory confirmation, meaning the toxin found in blood, in gut contents or in the suspect food, takes a long time to arrive. Waiting for it before starting treatment is not an option, and a competent doctor will not do so. The diagnosis is made on the clinical picture, and the test confirms it after the fact.

How it is treated

Treatment is only possible in hospital, usually in intensive care, and it has two parts.

The first is antitoxin, ready-made antibodies that mop up the poison in the blood. Different preparations are used for adults and for babies. The second, no less important, is supporting the body while the nerve endings rebuild themselves: watching the breathing, mechanical ventilation if it is needed, feeding through a tube, and preventing pressure sores and clots.

In the wound form the wound is cleaned surgically and antibiotics are added. In the infant form, by contrast, antibiotics are not the mainstay, and some of them can make things worse, so they must never be started on your own initiative.

Recovery is slow. Weakness and easy tiredness, a dry mouth and difficulty focusing the eyes can last for months. Botulism still proves fatal in roughly one case in ten to twenty, and almost always these are cases where help came late.

What genuinely lowers the risk

• do not seal mushrooms, meat or fish into jars at home, as these account for most cases; low-acid vegetables are safer fermented or salted in an open container and kept cold;
• throw out without regret any jar with a bulging lid, seepage down the side, cloudy brine or bubbles rising from the bottom;
• remember that look, smell and taste guarantee nothing: contaminated food usually looks and smells perfectly normal;
• heat home preserves before eating them, since the toxin itself is destroyed by ten minutes of boiling, though that does not kill the spores;
• do not leave vacuum-packed fish, smoked foods or cooked dishes wrapped in foil standing at room temperature;
• give no honey to a child under one year, neither on its own, nor in a drink, nor on a dummy;
• have deep, dirty wounds cleaned by a professional rather than dealt with at home;
• before any cosmetic procedure, ask exactly what is being injected, whether the product is licensed, and whether the person holding the needle has medical training.

Online consultation

An online consultation is no substitute for emergency care once symptoms have set in, but it is useful for something else: the doctor can help you judge how dangerous yesterday's jar really was, explain which signs to watch for over the next day and at what point to call for help, go through home preserving rules as they apply to your own kitchen, and advise on what to do about a wound or about doubts after a cosmetic procedure.

This material is for information only and does not replace medical advice.