Tetanus

From Wikipedia, the free encyclopedia

**Tetanus**
*Classifications and external resources*
ICD-10	A 33.-A 35.
ICD-9	037, 771.3
DiseasesDB	2829
MedlinePlus	000615
eMedicine	emerg/574

Tetanus is a medical term indicating a prolonged contraction of skeletal muscle fibers. Tetanus is the primary symptom caused by the neurotoxin, tetanospasmin, 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 of other parts of the body.<ref name=Baron>Wells CL, Wilkins TD (1996). Clostridia: Sporeforming Anaerobic Bacilli. In: Baron's Medical Microbiology (Baron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.</ref> The term tetany refers to a state of muscle tension.

Infection can be prevented by proper immunization, as well as by post-exposure prophylaxis. Image:CBell1809.jpg

1 Signs and Symptoms
2 Treatment
- 2.1 Mild tetanus
- 2.2 Severe tetanus
3 Prevention
4 Epidemiology
5 Association with rust
6 References
7 External links

[edit] Signs and Symptoms

Tetanus affects skeletal muscle, a type of striated muscle. The other type of striated muscle, cardiac or heart muscle cannot be tetanized due to intrinsic electrical properties.

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 higher the chance of death. In neonatal tetanus, symptoms usually appear from 4 to 14 days after birth, averaging about 7 days. On the basis of clinical findings, four different forms of tetanus have been described.

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

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

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, followed by stiffness of the neck, difficulty in swallowing, and rigidity of abdominal muscles. Other symptoms include elevated temperature, sweating, elevated blood pressure, and episodic rapid heart rate. Spasms may occur frequently and last for several minutes. Spasms continue for 3–4 weeks and complete recovery may take months. Image:Neonatal tetanus 6374 lores.jpg

Neonatal tetanus is a form of generalized tetanus that occurs in newborn infants. The neonatal form occurs in infants born without protective 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 an non-sterile instrument. Neonatal tetanus is common in many developing countries, and is responsible for 14% (215,000) of all neonatal deaths,<ref>World Health Organization 1998 Maternal and Neonatal Tetanus pdf</ref> but is very rare in developed countries.

[edit] Treatment

The wound must be cleaned; dead and infected tissue should be removed by surgical debridement. Metronidazole treatment decreases the amount of bacteria but has no effect on the bacterial toxin. Penicillin has been used in the past to treat tetanus, but is no longer the treatment of choice because of a theoretical risk that it increases spasms; however, if metronidazole is not available penicillin should still be used. Passive immunization with human anti-tetanospasmin immunoglobulin (or tetanus immune globulin) is a crucial part of treatment; if specific anti-tetanospasmin immunoglobulin is not available then human normal immunoglobulin may be given instead. All tetanus victims should be vaccinated against tetanus or offered a booster vaccine if they have been previously vaccinated. In the most severe of cases, it may be necessary to paralyze the patient using a naturally occurring substance, and engage a machine to continue breathing.

It takes 2-14 days for symptoms to develop after infection. Symptoms peak 17 days after infection. Image:PHIL 2857 thumb.jpg

[edit] Mild tetanus

Mild cases of tetanus can be treated on the ward. In addition to the measures given above:

5000 units tetanus immune globulin IV or IM
metronidazole 500mg IV for 10 days
diazepam 5 to 20mg tds PO
tetanus vaccination

[edit] Severe tetanus

These patients will require admission to intensive care. In addition to the measures listed above for mild tetanus:

human tetanus immunoglobulin 1000 units injected intrathecally (increases clinical improvement from 4% to 35%)
tracheostomy and mechanical ventilation for 3 to 4 weeks
magnesium, as an intravenous infusion, to prevent muscle spasm
diazepam 20 to 100mg per day continuous IV infusion
autonomic features can be difficult to manage (alternating hyper- and hypotension, hyperpyrexia/hypothermia) and may require IV labetalol, magnesium, clonidine, nifedipine, etc.

Sedation is often given for muscle spasm, as it can lead to life-threatening breathing difficulty. Drugs such as chlorpromazine or diazepam, or other muscle relaxants are given by IV can control the muscle spasms. In extreme cases it may be necessary to chemically paralyze the patient with curare-like drugs and use a mechanical ventilator. In order to survive tetanus, it is essential that breathing and nutrition are carefully maintained. An intake of 3500-4000 calories, with at least 100g of protein, is often taken in liquid form through a tube directly into the stomach, or through a drip into a vein. This high-caloric diet maintenance is required due to the increased metabolic strain brought on by the increased muscle activity.

[edit] Prevention

Tetanus can be prevented by vaccination.<ref name=MMWR_1991> (1991) "Diphtheria, tetanus, and pertussis: recommendations for vaccine use and other preventive measures. Recommendations of the Immunization Practices Advisory committee (ACIP).". MMWR Recomm Rep 40 (RR-10): 1-28. PMID 1865873.</ref> The CDC recommends that adults receive a booster vaccine 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. This booster cannot prevent a potentially fatal case of tetanus from the current wound as it takes 2 weeks for antibodies to form. For children under the age of seven, the tetanus vaccine is often administered as a combined vaccine, TDap or DTaP, which include vaccines against diphtheria and pertussis as well. For adults and children over seven, the Td vaccine (tetanus and diphtheria) is commonly used.<ref name=MMWR_1991 />

[edit] Epidemiology

Image:Tetanos.png Tetanus is a global health problem since C. tetani and Geravium tetani spores are ubiquitous. The disease occurs almost exclusively in persons who are unvaccinated or inadequately immunized.<ref name=Baron /> Tetanus occurs worldwide but is more common in hot, damp climates with soil rich in organic matter. This is particularly true with manure-treated soils, the spores are widely distributed in the intestines and feces of many non-human animals such as horses, sheep, cattle, dogs, cats, rats, guinea pigs, and chickens. In agricultural areas, a significant number of human adults may harbor the organism. The spores can also be found on skin surfaces and in contaminated heroin.

Tetanus, particularly the neonatal form, remains a significant public health problem in non-industrialized countries. There are about one million cases of tetanus reported worldwide causing an estimated 300,000 to 500,000 deaths each year.

In the US, there are about 100 cases and approximately five deaths each year.<ref name=Tetanus7-14-05>Tetanus Cases Prompt Advisory for Missourians to Get Vaccine, Check Booster Status. NewsAndPublicNotices. Retrieved on 2006-09-20.</ref> Most cases in the US occur in unimmunized individuals or individuals who have allowed their inoculations to lapse, whereas most cases in developing countries are due to the neonatal form of tetanus.

Tetanus is not contagious from person to person. It is the only vaccine-preventable disease that is infectious but not contagious.

[edit] Association with rust

Anecdotally tetanus is often associated with rust, especially rusty nails, but this relationship is somewhat misleading. Objects that accumulate rust are often found outdoors, or in places that harbor anaerobic bacteria, but the 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 a C. tetani endospore to reside. An endospore is a non-metabolising survival structure that begins to metabolise and cause infection once in an adequate environment. Because C. tetani is an anaerobic bacterium, it, and its endospores, will thrive in an environment that lacks oxygen. Hence, stepping on an old nail (rusty or not) may result in a tetanus infection, due to the ideal bacterial breeding ground provided by the low-oxygen environment of a puncture wound.