TETANUS

A rusty nail, a clumsy step – and the resulting wound could be the ideal breeding ground for the virulent bacterium that causes tetanus. The disease can be fatal, so adequate immunization is of the utmost importance.

Tetanus is a frightening and dangerous disease that can often be fatal, even with the best of medical care. However, with all the techniques of intensive care that modern medicine has at its disposal, there is no doubt that the appropriate treatment does significantly reduce the number of deaths from this disease.

CAUSE

Tetanus is caused by a bacterium called Clostridium tetanus. This organism is found freely in the soil, and is more likely to be encountered in manured and cultivated soil since it is very common in animal dung. However it is not confined to the soil; street dust from the centre of a town certainly contains the spores of the bacteria and they can even be found inside buildings in quite large amounts.

The bacterium has one very important characteristic that control the way the disease behaves: it is killed off by oxygen and only grows in oxygen free surroundings. This is why the bacteria have to be introduced into the body via a wound of some sort, since the blood supply and therefore the oxygen supply are cut off as a result of the tissue damage. The deeper and more contaminated a wound is, the worse the risk of tetanus.

The toxin that the bacterium makes is a deadly substance, exceeded in potency only by the toxin responsible for botulism. A tenth of a milligram is the fatal dose for an adult. From its site of production in the wound contaminated by the bacteria, the toxin passes into the spinal cord and the brain. It is thought that it travels through the nerves, although spread via the blood could also be important. Once in the nervous system the toxin cannot be neutralized by anti-bodies either produced by the body after immunization or given as antitoxin.

SYMPTOMS

The incubation period is six to ten days as a rule, although in rare cases it may be several months. At the other extreme symptoms can occur within a day. There is a short vague illness with headache, general illness and fever, but the important first signs and due to the generalized muscle rigidity that is one of the two classical symptoms of the disease. This especially affects the jaw muscles - giving rise to ‘lock jaw’ by which name the disease is sometimes known, and the muscles of the abdomen, which are found to be firm on examination, and the muscles of the back. Eventually the back may be arched right over and the neck bent right back.

Spasms develop later and can be brought on by any stimulus. Minor spasms may simply affect the face, with contraction of the facial muscles into a ghastly grin - known by the chilling sardonic smile. Breathing can be affected by these spasms and when they become more generalized they lead to even more exaggerated arching of the back and neck.

The difficulty in looking after tetanus patients really becomes marked when the disease interferes with the way that the brain controls vital functions. The heart may be affected, leading to abnormalities of rhythm and either very low, or very high blood pressure. Sometimes the temperature may shoot up rapidly.

TREATMENT

The aim of treatment is to tide the patient over the period of illness without any of the possible fatal problems occurring. These problems include exhaustion due to spasm, asphyxia during spasm, pneumonia due to stomach contents entering the lungs, and death due to disorders of control of vital functions such as the heartbeat and blood pressure.

In milder cases, simple sedation and the avoidance of all types of disturbance will prevent spasms, but in the more sever cases a tracheotomy is performed, and the patient is treated by total paralysis using curare (a paralyzing drug), while breathing is taken over by a ventilator.

The disease is likely to be most severe when the incubation period has been short, and when there has been less than 48 hours between the first symptom and the first spasm.

PREVENTION

Immunization with what is known as tetanus toxoid is given with a baby’s first immunization, and boosters are given when starting school and again on leaving. After that, a booster should be given every 5 years - or more often if you are at special risk, for example if you work on the land. In people who have not been immunized it is necessary to give an antitoxin after any serious wound.

It is possible to cut down the risks of the disease by very careful cleaning of wounds and the use of large doses of penicillin. However, adequate immunization can abolish the risk completely. This disease is often fatal and it is up to all of us to make sure that we are immunized.