If Clostridium tetani bacteria get into a deep wound they reproduce but do not invade the tissues. They do, however, produce a toxin which is extremely poisonous. This toxin passes up the motor nerve fibre to the spinal chord. Here, it does not paralyzed the motor nerve but makes them extremely sensitive, so that the slightest stimulus sets off a reflex contraction of the muscles. This may cause spasmodic twitching or strong, sustains contractions. An early symptom is often a spasm of the jaw muscles which makes it difficult to open the Jaw. This symptom gives the illness its popular name of “lock-jaw “. However, the convulsion may affect nearly all the body muscles and be so severe that the patient cannot breathe. If the patient can be kept alive for 3-4 weeks, they will get better of their own accord. The patients need to be watch all the time to help the breathing if necessary and to make sure that if they vomit the airway does not become blocked.
The drugs used are [a] Antibiotics to attack the clostridium bacteria in the wound, [b] sedatives to suppress the convulsions and, [c] an anti-toxin to neutralize the Toxin.
The anti-toxin is prepared by injecting a horse with diluted tetanus toxin. The horse makes an antitoxin which can be extracted from its blood serum and injected into humans. The anti-toxin cannot reach the toxin already in the nerve system but it does the neutralize any toxin circulating in the bloodstream.
The best time to use the anti-toxin is immediately after receiving a wound which is likely to have become contaminated with soil or animal faeces. In the case, the anti-toxin will neutralize any tetanus toxin in the blood before the toxin can reach the nerve. The tetanus anti-toxin is eliminated from the in a week or two.
There is a danger of an allergic reaction to the horse serum, so a skin test with a small amount of serum is necessary before injecting a larger dose. If the skin shows an inflammatory reaction to the serum anti-toxin is not used. Anti-toxin prepared from human serum is far less to provoke an, allergic reaction.
The Clostridium tetani bacteria occur in the faeces of cow, horses, dog and, rarely man, and the bacteria spores can survive in the soil. People working on the land or with animals are therefore the most likely to contract the disease if they cut themselves. People who do not wear the shoes are also at risk. The use of animal dung to treat wounds or rubbing on the cut umbilical cord of new born babies is a highly undesirable practice because of the risk of infection with Clostridium.
The most effective way of preventing tetanus is by Immunization. A harmless form of the tetanus toxin is called a texoid, can be prepared. When this is injected, the body makes an anti-toxin. Everyone should be immunized against tetanus, regardless of age, but it is especially important for people who work with soil and domestic animals. Pregnant women should be immunized early in pregnancy and children at six months.
Immunity is not long –lasting and does not develop after only one inoculation. So, a series of anti- tetanus injections are needed. The first two are given four weeks apart, followed by a third, 8-12 months later. After this, ‘booster’ injection are needed every ten years.