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Tetanus

This article describes the disease, tetanus. For the state of tetanus in biomechanics, see tetanized state.

Tetanus is a serious and often fatal disease caused by the exotoxin tetanospasmin which is produced by the Gram-positive, anaerobic bacterium Clostridium tetani.

It was first documented by Hippocrates, and records dating back to the 5th century BCE provide countless clinical observations of the disease. However, the etiology of the disease was not discovered until 1884 by Carle and Rattone. Passive tetanus immunization was first implemented during World War I.

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, and contaminated heroin.

Tetanus is contracted through open wounds. These wounds are commonly caused by sharp objects in the ground such as rusty nails, however it is not the rust that is the problem, but rather that the nail has been exposed to the environment for a long time, causing the rust, and possibly accumulating some of the tetanus bacteria from the soil.

There are three different clinical forms of tetanus: local (uncommon), cephalic (rare), and generalized (most common). Generalized tetanus accounts for 80% of tetanus cases.

The incubation period for tetanus is 3–21 days (with the average being about 8 days). For neonates, the incubation period is 4–14 days, with 7 days being the average. Most of the time, the farther the wound is from the central nervous system, the longer the incubation period. Incubation period length and likelihood of death are inversely proportional.

The first sign of tetanus is 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. Typical signs of tetanus include an increase in body temperature by 2–4 C, diaphoresis (excessive sweating), an elevated blood pressure, and an episodic rapid heart rate. Spasms and muscle contraction last for 3–4 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 sixty percent.

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.

Treatment: The wound must be cleaned. Penicillin and metronidazole will help decrease the amount of bacteria but it has no effect on the toxoid produced by the bacteria. Human anti-tetanospasmin immunoglobulin should be given. Diazepam and DTP vaccine booster are also given.

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. There was a shortage of tetanus vaccine in the United States in 2001 and 2002, but this supply issue was corrected in 2003.

There are, on average, around 150 cases annually in the USA.

Tetanus and 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 a rusty nail, such as one in a barn or stable could easily result in tetanus, partly because C. tetani is found in animal feces (which is abundant in a barn or stable) and the puncture wound would effectively create an ideal breeding ground for the bacteria (because of the lack of oxygen). 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.

References

Last updated: 10-19-2005 18:47:59
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