Tetanus overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Tetanus is a medical condition that is characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, obligate anaerobic bacterium Clostridium tetani. Infection generally occurs through wound contamination, and often 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 swallowing and general muscle stiffness and spasms in other parts of the body.[1] Infection can be prevented by proper immunization and by post-exposure prophylaxis.[2]
Tetanus affects skeletal muscle, a type of striated muscle. The other type of striated muscle, cardiac or heart muscle cannot be tetanized because of their 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 bacteria 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 clinical manifestations of tetanus are caused when tetanus toxin blocks inhibitory nerve impulses, by interfering with the release of neurotransmitters. This leads to unopposed muscle contraction and spasm. Seizures may occur, and the autonomic nervous system may also be affected. The term tetany refers to sustained muscle contraction that is not caused by tetanus.
Historical Perspective
In 1884 Carle and Rattone discovered tetanus by injecting animals with pus from a patient who had died of tetanus. In 1924 Descombey developed the tetanus toxoid, which was extensively utilized in the second World War.
Classification
Tetanus can be classified with respect to its patterns of presentation into neonatal, cephalic, generalized or local.
Pathophysiology
The bacteria that causes tetanus, Clostridium tetani is introduced into the human body usually by a wound. The toxins produced by the bacterium, utilize the blood and/or lymphatics to gain access to target tissues. The toxins can act at various places in the central nervous system, including the spinal cord, peripheral motor end plates, and the brain. They can also act on the sympathetic nervous system.[3][4]
Causes
Clostridium tetani is a rod-shaped, anaerobic bacterium of the genus Clostridium. Like other Clostridium species, it is Gram-positive, and its appearance on a gram stain resembles tennis rackets or drumsticks.[5] C. tetani is found as spores in soil or as parasites in the gastrointestinal tract of animals. C. tetani produces a potent biological toxin, tetanospasmin, and is the causative agent of tetanus.
Differentiating Tetanus from other Diseases
Tetanus must be differentiated from *Strychnine poisonings differential diagnosis==
Epidemiology and Demographics
Tetanus is the only vaccine-preventable disease that is infectious but is not contagious. In the US, there are fewer than 100 cases and approximately five deaths each year. There are about one million cases of tetanus reported worldwide, causing an estimated 300,000 to 500,000 deaths each year.
Risk Factors
People in developing countries are more at risk because of lack of vaccination.
Natural History, Complications and Prognosis
Tetanus can have an incubation period of 2 to 38 days with the man being 7 to days post exposure. The presentation and progression may vary depending on the type of tetanus. Generalized tetanus can involve the respiratory muscles making it difficult to breathe. The complications of tetanus include fractures, laryngospasm, aspiration pneumonia and pulmonary embolism. Tetanus has a fatality rate of almost 11%. The fatality rate of tetanus might be associated with prolonged convulsions and contractions. Tetanus without spasms has an excellent prognosis. Early diagnosis is also associated with a good prognosis.[6][7]
Diagnosis
History and Symptoms
Tetanus incubation period ranges from 3 to 21 days. Tetanus may present with either Local Tetanus, Cephalic Tetanus or Generalized Tetanus. Neonatal Tetanus occurs through infection of the unhealed umbilical stump, particularly when the stump is cut with a non-sterile instrument.
Physical Examination
The diagnosis of tetanus is completed through a physical examination. Tetanus infection produces some very clear symptoms that will be used for a clinical diagnosis.
Laboratory Findings
There are no laboratory findings characteristic of tetanus. The diagnosis is entirely clinical and does not depend upon bacteriologic confirmation. C. tetani is recovered from the wound in only 30% of cases and can be isolated from patients who do not have tetanus. Laboratory identification of the organism depends most importantly on the demonstration of toxin production in mice.
Treatment
Medical Therapy
Dead and infected tissue should be removed by surgical debridement. Metronidazole treatment decreases the number of bacteria but has no effect on the bacterial toxin. Passive immunization with human anti-tetanospasmin immunoglobulin or tetanus immune globulin is crucial. Drugs such as chlorpromazine or diazepam, or other muscle relaxants can be given to control the muscle spasms
Primary Prevention
A very common primary prevention method for tetanus is vaccinating against the bacteria which causes tetanus, clostridium tetani.
Secondary Prevention
Tetanus vaccine can prevent Tetanus for approximately 10 years. Post-exposure care is indicated in people who do not know exactly when their last Tetanus booster was and who did not complete their primary prevention set of vaccinations. These patients will typically receive passive immunity with tetanus immune globulin (TIG).
Cost-Effectiveness of Therapy
The major cost encountered with tetanus is in the form of the vaccine. There are many different trade names associated with the tetanus vaccine that come with slightly different costs. The prices of the vaccines are all listed in the following tables. The tables are separated based upon pediatric doses versus adult doses. The DTaP vaccine that is mentioned in the passage stands for Diptheria, Tetanus, and Pertussis.
References
- ↑ Wells CL, Wilkins TD (1996). Clostridia: Sporeforming Anaerobic Bacilli. In: Baron's Medical Microbiology (Baron S et al, eds.) (4th ed. ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
- ↑ "Tetanus" (PDF). CDC Pink Book. Retrieved 2007-01-26.
- ↑ Farrar JJ, Yen LM, Cook T, Fairweather N, Binh N, Parry J; et al. (2000). "Tetanus". J Neurol Neurosurg Psychiatry. 69 (3): 292–301. PMC 1737078. PMID 10945801.
- ↑ Lalli G, Gschmeissner S, Schiavo G (2003). "Myosin Va and microtubule-based motors are required for fast axonal retrograde transport of tetanus toxin in motor neurons". J Cell Sci. 116 (Pt 22): 4639–50. doi:10.1242/jcs.00727. PMID 14576357.
- ↑ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0838585299.
- ↑ Thwaites CL, Beeching NJ, Newton CR (2015). "Maternal and neonatal tetanus". Lancet. 385 (9965): 362–70. doi:10.1016/S0140-6736(14)60236-1. PMID 25149223.
- ↑ J. C. Patel & B. C. Mehta (1999). "Tetanus: study of 8,697 cases". Indian journal of medical sciences. 53 (9): 393–401. PMID 10710833. Unknown parameter
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