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Introduction Tetanus is a serious infection of the nervous system caused by the germ Clostridium tetani, which is usually found in cultivated soil and manure. Clostridium tetani forms tough spores that can survive for many years. If these spores get into a deep wound, they can germinate. Once this happens the germ produces a powerful poison called tetanospasmin toxin which damages the nervous system and can cause death. Tetanus is commonly known as lockjaw because of its characteristic symptoms which include tightening of the muscles in the face. Today tetanus has been largely eliminated by immunisation, higher hygiene standards, better medical services and the mechanisation of farming. Tetanus is very rare in England although it is still a common cause of death in developing countries. Modern methods of treatment have reduced the death rate from 60 per cent to about 20 per cent of those that become infected. However, in the developing world death rates from the infection are still around 50%.
Symptoms Sometimes, the first and only sign of tetanus is a spasm of the muscles nearest to the infected wound. However, once the tetanospasmin toxin gets into the bloodstream, other symptoms start, usually in the face. The most common early sign is a spasm of the chewing muscles (trismus) which makes it very hard to open the mouth (hence the common name of lockjaw). As the infection progresses, spasms occur in the throat muscles, making it difficult to swallow. This can be followed by spasms in the facial muscles which can make it seem like the persons face has a sardonic grin. This is sometimes known by its medical name risus sardonicus. The spasms may spread to other muscles: to the neck making the head tilt; to the chest, making breathing difficult; to the stomach wall and to arms and legs. If the spasms spread to the back muscles, the spine may become strongly arched backwards. This is known as opisthotonus and is most common in children with the infection. Other symptoms include extreme sensitivity to touch, high fever, sore throat, rapid heartbeat, difficulty breathing, headache, bleeding into the bowels, and diarrhoea. The direct cause of death may be blood poisoning, suffocation (asphyxia) in the course of a muscle contraction, the heart stopping (cardiac arrest), kidney failure or exhaustion. If left untreated, death occurs in around 60% of cases.
Causes The germ Clostridium tetani usually enters the body via a penetrating wound which is contaminated with soil or manure. There is more chance of developing tetanus if the wound is deep and contamination is great. However, infection can occur from minor wounds and in some cases, no wound can be found. Intravenous drug users are also at risk from tetanus infection. Once inside the body, the germ develops and produces a strong poison called tetanospasmin toxin. It is the poison that causes the muscle contractions and other symptoms as it spreads through the body. The only area of the body that the poison does not reach is the brain. Here, the poison molecules are too large to pass through the tiny openings between the wall cells of the smallest blood vessels in the brain (known as the blood brain barrier). The infection can take between two days and two months to develop (known as the incubation period). This will depend on the site of the wound and how much it was contaminated. Generally, the shorter the incubation period, the more severe and dangerous the infection is likely to be.
Diagnosis A diagnosis will usually be made by a health professional. The diagnosis will be based on taking details of the persons recent history including: Whether the person has been injured or wounded Whether the wound was contaminated with soil, manure or anything else that could contain Clostridium tetani spores A firm diagnosis will also be based on an observation of the symptoms, clinical signs and a blood test.
Treatment If the wound is large, standard practice is to remove as much of the damaged and contaminated muscle as possible by surgery. This will limit the amount of the poison tetanospasmin toxin that can be produced. The surgical process is called debridement. Where tetanus has become established, the treatment is to give antibodies that work against the poison (known as tetanus antitoxins). This will usually be human antitetanus globulin. Large doses of antibiotic drugs, antimicrobial drugs (such as metronidazole) and a muscle relaxant (such as diazepam) are usually given once a tetanus diagnosis is suspected. Giving the drug diazepam directly into a vein can control the muscle spasms themselves. In extreme cases it may be necessary to paralyse the patient with curare (a naturally occurring substance that paralyses the nerves to muscles) and use a machine to keep the person breathing. Maintaining breathing and nutrition are very important for helping someone to survive tetanus as the infection can cause severe energy loss. Maintaining a calorie intake of 3500-4000 calories with at least 100g of protein by giving it in liquid and semi-liquid form via a stomach tube is recommended. In some cases, feeding via an intravenous drip may be necessary.
Prevention Tetanus can be easily prevented by vaccination. England has a national vaccination programme for tetanus which has greatly reduced the number of cases each year. Immunisation is achieved by injecting a small amount of tetanus toxoid (a form of the tetanospasmin poison which has been made harmless) into the body. This is usually given in infancy in a triple vaccine (Diphtheria, tetanus, whooping cough) in three doses at monthly intervals. This gives total protection for one year and a high degree of partial protection remains for many years. The first three doses are often followed up by two booster doses: one on starting school and the other on leaving school. Combined tetanus / low-dose diphtheria vaccine is now used rather than tetanus alone for these boosters. The full five doses are considered to give lifelong immunity. Booster doses should also be given in the following circumstances: Following a wound which may give rise to tetanus where the person has not had the full five doses or where this information is not known. However, if the wound is contaminated, a dose of tetanus antibodies (known as human tetanus immunoglobulin) should be given. For travellers to areas where medical attention might not be available should an injury occur that might give rise to tetanus and the last dose was more than 10 years previously. Experiencing tetanus does not itself produce immunity to a second infection. People who have had tetanus should still be immunised when they have recovered.
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