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Tetanus Print E-mail

Dr. Kennedy

Tetanus is characterized by a prolonged contraction of skeletal muscles. Symptoms are caused by a neurotoxin (tetanospasmin) produced by the Gram-positive, obligate anaerobic bacterium Clostridium tetani. Infection generally occurs through wound contamination, and usually involves a cut or deep puncture wound. As the infection progresses, muscle spasms in the jaw develop, hence the common name, lockjaw. This is followed by difficulty in swallowing and generalized muscle stiffness and spasms.

General Comments

Tetanus affects skeletal muscle, a type of striated muscle. The other type of striated muscle (heart muscle) cannot be affected by tenaus because of its intrinsic electrical properties. In recent years, approximately 11% of reported tetanus cases have been fatal. The highest mortality rates are in unvaccinated persons and persons over 60 years of age. C. tetani, the bacterium that causes tetanus, is recovered from the initial wound in only about 30% of cases, and can be found in patients who do not have tetanus. The incubation period of tetanus ranges from 3 to 21 days, with an average onset of clinical presentation of symptoms in 8 days. In general, the further the injury site is from the central nervous system, the longer the incubation period. The shorter the incubation period, the greater the chance of death.

Epidemiology

Tetanus is a global health problem, as C. tetani spores are ubiquitous. The disease occurs almost exclusively in persons who are unvaccinated or inadequately immunized. Tetanus is more common in hot, damp climates with soil rich in organic matter. This is particularly true with manure-treated soils, as the spores are widely distributed in the intestines and feces of many animals such as horses, sheep, cattle, dogs, cats, rats, guinea pigs, and chickens. In agricultural areas, a significant number of human adults may harbour the organism. The spores can also be found on skin surfaces and in contaminated heroin. The neonatal form is a significant public health problem in non-industrialized countries. There are about one million cases of tetanus reported worldwide each year, causing an estimated 300,000 to 500,000 deaths. In the U.S. approximately 100 people become infected with tetanus each year, and there are about five deaths from tetanus each year. Almost all of the cases in the U.S. occur in unimmunized individuals or individuals who have allowed their inoculations to lapse. Most cases in developing countries are due to the neonatal form of tetanus. Tetanus is the only vaccine-preventable disease that is infectious but is not contagious. Tetanus is often associated with rust, especially rusty nails, but this concept is misleading. Objects that accumulate rust are often found outdoors, or in places that harbour anaerobic bacteria, but rust itself does not cause tetanus nor does it contain more C. tetani bacteria. The rough surface of rusty metal merely provides a prime habitat for C. tetani endospore to reside. An endospore is a non-metabolizing survival structure that begins to metabolize and cause infection once in an adequate environment. Because C. tetani is an anaerobic bacterium, it and its endospores thrive in an environment that lacks oxygen. Hence, stepping on a nail (rusty or not) may result in a tetanus infection, as the low-oxygen (anaerobic) environment of a puncture wound provides the bacteria with an ideal breeding ground.Signs and Symptoms of the Various Types

Varieties of Tetanus

Generalized tetanus is the most common type of tetanus, representing about 80% of cases. The generalized form usually presents with a descending pattern. The first sign is trismus, or lockjaw, and the facial spasms called risus sardonicus ("sarcastic smile"), followed by neck stiffness, difficulty swallowing, and rigidity of pectoral and calf muscles. Other symptoms include elevated temperature, sweating, elevated blood pressure, and episodic rapid heart rate. Spasms may occur frequently and last for several minutes with the body shaped into a charcateristic backward bow-shaped form called opisthotonos. Spasms continue for three to four and complete recovery may take months.

Local tetanus is an uncommon form of the disease in which patients have persistent contraction of muscles in the anatomic area of the injury. The contractions may persist for many weeks before gradually subsiding. Local tetanus is generally milder with only about 1% of cases fatal, but it may precede the onset of generalized tetanus.

Neonatal tetanus occurs in newborn infants who have not acquired passive immunity because the mother has never been immunized. It usually occurs through infection of the unhealed umbilical stump, particularly when the stump is cut with a non-sterile instrument. Neonatal tetanus is common in many developing countries and is responsible for about 14% of all neonatal deaths, but is rare in developed countries. Symptoms usually appear from four to 14 days after birth, averaging about 7 days.

Cephalic tetanus is a rare form of the disease, occasionally occurring with middle ear infection in which C. tetani is present in the middle ear, or following injuries to the head. There is involvement of the cranial nerves, especially in the facial area.

Spatula Test

The spatula test for tetanus involves touching the posterior pharyngeal wall with a sterile, soft-tipped instrument, and observing the effect. A positive test result is the involuntary contraction of the jaw (biting down on the tongue blade, the "spatula"), and a negative test result would normally be a gag reflex. The spatula test has a high specificity (few or no false positive test results) and a high sensitivity (almost all infected patients produce a positive test result).

Treatment

The wound is cleaned, dead and infected tissue is removed by surgical debridement. Metronidazole treatment decreases the number of bacteria but has no effect on the bacterial toxin. Penicillin was once used to treat tetanus, but is no longer the treatment of choice, owing to a theoretical risk of increased spasms. However, its use is recommended if metronidazole is not available. Passive immunization with human anti-tetanospasmin immunoglobulin or tetanus immune globulin is crucial. If specific anti-tetanospasmin immunoglobulin is not available, then normal human immunoglobulin may be given instead. All tetanus victims should be vaccinated against the disease or offered a booster shot.

Mild cases of tetanus can be treated with:

  • tetanus immune globulin IV or IM
  • metronidazole IV for 10 days
  • diazepam
  • tetanus vaccination
  • tetanus shots
  • tetanus digestion

Severe cases will require admission to intensive care. In addition to the measures listed above for mild tetanus. In the case of lock-jaw in a patient suffering from tetanus

  • human tetanus immunoglobulin injected intrathecally
  • tracheostomy and mechanical ventilation for 3 to 4 weeks,
  • magnesium, as an intravenous (IV) infusion, to prevent muscle spasm,
  • diazepam (known under the common name Valium) as a continuous IV infusion,

The autonomic effects of tetanus can be difficult to manage (alternating hyper- and hypotension, hyperpyrexia / hypothermia) and may require IV labetalol, magnesium, clonidine, or nifedipine. Drugs such as chlorpromazine or diazepam, or other muscle relaxants can be given to control the muscle spasms. In extreme cases it may be necessary to paralyze the patient with curare-like drugs and use a mechanical ventilator.

Maintenance of an airway and proper nutrition are required in order to survive a severe case of tetanus. An intake of 3500-4000 Calories, and at least 150 grams of protein per day, is often given in liquid form through a nasogastric tube directly into the stomach, or through an IV drip. This high caloric diet maintenance is required because of the increased metabolic strain brought on by the increased muscle activity.

Prevention

Tetanus can be prevented by vaccination. The CDC recommends that adults receive a booster vaccine every ten years, and standard care practice 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, or if he or she has had fewer than 3 lifetime doses of the vaccine. It can take up to two weeks for tetanus antibodies to form. Therefore, the booster cannot prevent a potentially fatal case of tetanus from the current wound. In children under the age of seven, the tetanus vaccine is often administered as a combined vaccine, DPT vaccine, which also includes vaccines against diphtheria and pertussis. For adults and children over seven, the Td vaccine (tetanus and diphtheria) or Tdap (tetanus, diphtheria, and acellular pertussis) is commonly used.



The information in this article is not meant to be medical advice.�Treatment for a medical condition should come at the recommendation of your personal physician.

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