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Tetanus
From Wikipedia, the free encyclopedia

Tetanus is a serious and often fatal disease caused by the neurotoxin tetanospasmin which is produced by the Gram-positive, obligate anaerobic bacterium Clostridium tetani. Infection usually originates from a contaminated wound, often a cut or deep puncture wound. Common symptoms are muscle spasms in the jaw (hence the common name lockjaw), followed by difficulty swallowing and general muscle stiffness in other parts of the body. Infection can be prevented by proper immunization, as well as by post-exposure prophylaxis.

"Tetanus" can also refer to a state of muscle tension.

Bacilli of C. tetani can be found in soil (especially agricultural soil), and the intestines and feces of horses, sheep, cattle, rats, dogs, cats, guinea pigs, and chickens. Spores are found in manure-treated soil, skin surfaces (of both animals and humans), under nail-beds, and in contaminated heroin.

There are four different clinical forms of tetanus: local (uncommon), cephalic (rare), generalized (most common), and neonatal (a common cause of infant mortality in underdeveloped countries). Generalized tetanus accounts for 80% of tetanus cases.

Symptoms

The incubation period for tetanus is 3 days to as long as 15 weeks (with the average being about 8 days). For neonates, the incubation period is 4 to 14 days, with 7 days being the average. Most of the time, the further the wound is from the central nervous system, the longer the incubation period. Incubation period length and likelihood of death are inversely proportional; a deep, contaminated wound that allows the bacteria to flourish and causes a quick, aggressive infection is much more life-threatening than a shallower, less-contaminated wound that causes milder symptoms to appear days or weeks later.

The first sign of tetanus is a mild jaw muscle spasm called lockjaw (trismus), followed by stiffness of the neck and back, risus sardonicus, difficulty swallowing, and muscle rigidity in the abdomen. The stiffness and spasming of muscles expands throughout the body inferiorly, and can be so powerful that they cause muscle tears and even fractures[2]. These muscle contractions are due to tetanospasmin—a chemical released by C. tetani—which inhibits the release of both GABA and glycine, the neurotransmitters that serve to inhibit muscle contraction.

Typical signs of tetanus include an increase in body temperature by 2 to 4°C, diaphoresis (excessive sweating), an elevated blood pressure, and an episodic rapid heart rate. Spasms and muscle contraction last for 3 to 4 weeks, and complete recovery may take months. About 30% of tetanus victims die, most of whom are elderly patients. In developing countries, the mortality rate may be as high as 60%.

Complications of the disease include spasms of the larynx (vocal cords), accessory muscles (chest muscles used to aid in breathing), and the diaphragm (the primary breathing muscle); fractures of long bones secondary to violent muscle spasms; and hyperactivity of the autonomic nervous system.

Prevention

Tetanus can be prevented by vaccination. A booster vaccine is recommended every ten years, and standard care in many places is to give the booster to any patient with a puncture wound who is uncertain of when he or she was last vaccinated. One Tetanus booster used presently is called TDap or DTaP (a protection from Diphtheria and Pertussis as well). The risk from Tetanus, Diphtheria and Pertussis (whooping cough) is higher than the risk of vaccine side-affects. There was a shortage of tetanus vaccine in the United States in 2001 and 2002, but this supply issue was corrected in 2003.Worldwide, there are approximately one million cases of tetanus each year. (There are about 100 cases and approximately five deaths each year in the .)

Association with rust

Tetanus is often associated with rust, especially rusty nails, but this is somewhat misleading. Rust itself does not cause tetanus or contain more C. tetani bacteria. Objects that accumulate rust are often found in the outdoors or places that generally contain more bacteria. Since C. tetani is an anaerobic bacterium, it will thrive in an environment that lacks oxygen. Therefore, stepping on an old forgotten nail in a stable could easily result in tetanus, partly because C. tetani is found in animal feces (which is rather abundant in a stable) and the puncture wound would effectively create an ideal breeding ground for the bacteria (because of the lack of oxygen). Such an old nail would likely be rusty, but a lack of rust would provide no protection. On the other hand, someone scratching themselves against a rusty fire escape ladder in an urban setting would have a much lesser chance of getting tetanus since fire escape ladders do not often come into intimate contact with soil, dirt or organic waste and the wound itself (a scratch) does not create an oxygen-poor environment.