Food Safety – Botulism

What is Botulism?

Botulism is a very rare, but extremely serious, form of food poisoning.

What causes Botulism?

Botulism is caused by the bacterium Clostridium botulinum, which produces one of the most powerful toxins known to man which is lethal even in very small doses. When contaminated food is eaten, the toxin is rapidly absorbed through the small intestine and is carried into the blood-stream before attacking the nervous system. The organism is present in the soil and rotting vegetation, where it usually presents no risk because of its anaerobic properties (it can grow only in the absence of oxygen).

There is one strain of Clostridium botulinum associated with fish, and botulism has been traced to vacuum-packed fish in some cases. Smoked and salted foods have also been responsible for some outbreaks. However, by far the most common culprits are tinned Products, where food is packed, processed, and sealed in airtight containers, which provide ideal conditions for the growth of any bacteria that are present.

Commercial canners have a very good safety record, and there have been only seven outbreaks in the UK between 1922 and 1986. There have been more cases involving
botulism in the USA, where home bottling and canning have always been more popular. The Clostridium botulinum bacteria and, in particular, its spores, can be destroyed only by heating at very high temperatures, usually for long periods of time. Problems arise when the bacteria are not killed, or when the tins are not properly sealed, so that organisms can enter the can, for example, from contaminated water used to cool the food. The bacteria thrive in food of low acidity (so tinned fruit, for instance, is rarely affected). The toxins are easily destroyed by heating, but most cases of botulism involve fish or meats that are eaten from the can without further cooking.

How is Botulism diagnosed and treated?

The first symptoms occur after an incubation period of 12-36 hours, and often resemble those of other gastro-intestinal upsets. Nausea, vomiting and diarrhoea are followed by constipation, a bloated abdomen, and then a dry mouth and throat. The distinguishing symptoms of botulism that should alert the doctor are those caused by the toxin attacking the nervous system, which leads to paralysis of the muscles. The result is headaches, dizzy spells, lethargy, blurred and double vision, and an unsteady gait. As the paralysis spreads to the muscles of the throat, speech becomes hoarse and halting, and swallowing and breathing become difficult. Until the final stages, the victim is usually fully conscious. Immediate treatment with antitoxins is vital if the victim is to be saved.

If I think I am suffering from Botulism, when should I see my doctor?

Contact your doctor at once if you have a severe stomach upset, particularly if it is accompanied by muscle weakness or any of the symptoms listed.

What will the doctor do?

If Botulism is suspected, the patient will immediately be transferred to an intensive care unit, where heart, respiration and muscle function can be monitored. Diagnosis is confirmed by testing the blood, urine or stomach contents for the toxin. If any suspect food has been left over, it will be taken for analysis. Anyone else who has eaten the same meal, will be checked for symptoms. The doctor will try to rid the body of any contaminated food remaining using a stomach pump, and possibly an enema (where fluid is passed into the rectum via an anal tube) to clear the rectum of stools. In addition to antitoxins, antibiotics may be prescribed to kill any bacterial infection.

Is Botulism dangerous?

Botulism is extremely dangerous. Unless diagnosed and treated at once, around 25% of victims die within days. Even those who survive, because they have absorbed a smaller amount of toxin or have stronger constitutions, will need prolonged careful nursing, and may take months to make a full recovery. However, poisoning from botulism-contaminated food is rare, and simple precautions will usually avoid it.

WARNING

The paralysis caused by the botulism toxin rapidly spreads to the muscles of the respiratory system, and the patient soon experiences difficulty breathing. Collapse
and death can swiftly follow, unless breathing is assisted. Tracheostomy, the cutting of the trachea (windpipe) and the insertion of a tube, may be carried out, as well as artificial ventilation. Since the patient cannot swallow, intravenous feeding may also be necessary.

What can be done to avoid Botulism?

Be careful when buying tinned foods. Do not choose tins that are rusty, dented, or whose ends are ballooning out. Store tins in a dry place, and keep in mind that tinned food does not have an indefinite shelf life. You should aim for a yearly turnover of all tinned items. After opening a tin, transfer any unused portion to another container, and keep the food covered, and refrigerated. However, it is important to note that low temperatures will not destroy any micro-organisms already present in the food.
Watch out for any warning signs that food is unfit to eat. For example, sometimes the bacteria will cause putrefaction, blackening the food and producing gases. However, in many instances, the food looks and tastes normal.

SYMPTOMS

• Nausea.
• Vomiting.
• Constipation.
• Diarrhoea.
• Blurred vision.
• Difficulty in talking or swallowing.
• Paralysis of limbs.
• Breathing difficulty.

Bill & Sheila’s Food Safety – Botulism

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