Tetanus is the result of infection with Clostridium tetani, a spore-forming Gram-positive obligate anaerobe. It was first described by Hippocrates in the 5th century BC.
Spores are found in virtually all soil, particularly soil rich in manure, but also in house dust and both animal and human faeces. Spores can enter even the smallest wound and in anaerobic conditions found in necrotic tissue, active infection or the presence of a foreign body produces tetanospasmin, a powerful exotoxin. This spreads via lymph and blood, and is transported up the nerves, binding irreversibly to neurons, and preventing inhibition of motor reflex responses to sensory stimuli. This results in the characteristic muscle spasms (severe enough to tear muscles, cause long bone fractures or spinal compression fractures) and rigidity.
Incidence and mortality
- It is rare in the UK. In 2007 there were 3 cases notified.
- It is largely a disease of the developing world and the poor, where there is inadequate vaccination, neonatal tetanus causing 23-75% of neonatal deaths. It killed 277,400 people worldwide in 1997.
- Mortality in the untreated is up to 45% (66% in neonates); with treatment is it <10%, the rate in those who have received 1-2 doses of vaccine previously being approximately half that of the unvaccinated.
- Age >60 years, lack of immunisation, poverty, drug addiction.
- Wounds contaminated with garden soil or manure and those caused by rusty metals are particularly dangerous.
- It can also complicate burns, ulcers, gangrene, snakebite, frostbite, otitis media, septic abortion, childbirth.
- It can also occur following IM injections in surgery.
- Tetanus neonatorum is associated with poor obstetric techniques. This is particularly the case with the practice of applying cow dung or clarified butter to the cut surface of the umbilical cord, in both Africa and India.
Incubation period is on average 7 or 8 days but can range from 1 day to 2 months. The shorter the incubation period, the worse the severity. 15-25% of cases show no evidence of recent wounds. Clinically, 3 forms are recognised:
- Generalised tetanus (80%); usually a descending pattern after prodromal fever, malaise and headache:
- Trismus (lockjaw, an associated later feature: risus sardonicus, a grin-like expression from fixed facial muscle spasm)
- Neck stiffness (which may develop into opisthotonus: arched body with hyperextended neck)
- Swallowing difficulties
- Abdominal muscle rigidity
- Muscular spasms (initially reflexive, then spontaneous)
- Local tetanus: this is uncommon, may precede generalised tetanus but, generally, is a self-limiting illness with painful muscle spasms localised to the site of injury.
- Cephalic tetanus: this is usually secondary to otitis media or a head injury, exhibiting cranial (especially facial) nerve palsies, and progressing to the generalised form if untreated.
Complications in severe generalised tetanus:
- Aspiration pneumonia
- Laryngospasm, which may lead to asphyxia
- Fractures from sustained contractions and convulsions
- Respiratory embarrassment with tachypnoea, and intermittent apnoea
- Autonomic nervous involvement leading to hypertension, dysrhythmias and cardiac arrest
- Tetanic seizures mimicking epilepsy - frequency and severity related to the severity of illness, and indicate poor prognosis
- Pulmonary embolus particularly in drug abusers and the elderly.
No specific diagnostic laboratory test; diagnosis is made clinically. Spatula test is useful: touching the back of the pharynx with a spatula elicits a bite reflex in tetanus, instead of a gag reflex.
- Give human tetanus immunoglobulin (antitoxin) IV before any other action. If only equine or bovine antiserum is available, do a test dose first.
- Delay local debridement (until a few hours after immunoglobulin given, because of risk of release of further toxin) to remove organisms, and create an aerobic environment.
- Penicillin (2 mega-units IV qds for 8 days) is used but its results are disappointing. The preferred alternative in sensitive patients is metronidazole.
- Supportive treatment with diazepam, with the addition of phenobarbital and chlorpromazine.
- Tracheostomy and ventilation may be required, with the addition of neuromuscular blocking agents.
- Autonomic disturbance requires appropriate treatment.
Tetanus infection does not confer immunity, and immediate vaccination (inactivated tetanus toxoid) is too slow to address a current infection. Antibiotic prophylaxis against tetanus in wound management is not indicated. Active infection should be treated appropriately.
- Clean minor wounds:
- >3 doses vaccine: no immunoglobulin, no vaccine, unless >10 years since previous dose, and complete 5-dose schedule.
- Unknown or <3 doses vaccine: no immunoglobulin, give vaccine, and complete 5-dose schedule.
- All other wounds:
- >3 doses vaccine: no immunoglobulin (unless there is a particularly high-risk wound, eg contaminated with manure), no vaccine unless >5 years since previous dose, and complete 5-dose schedule.
- Unknown or <3 doses vaccine: give immunoglobulin, give vaccine, and complete 5-dose schedule.
- Older age (especially >60 years)
- Shorter duration of symptoms - trismus, rigidity and dysphagia
- Severe disease at presentation
- Shorter period of onset
Maternal and neonatal tetanus
Maternal and neonatal tetanus claims about 180,000 lives worldwide every year, almost exclusively in developing countries:
- Neonatal tetanus occurs in the first 28 days of life.
- Maternal tetanus is defined as tetanus during pregnancy, or within 6 weeks of the end of pregnancy (whether pregnancy ended with birth, miscarriage, or abortion.)
Maternal and neonatal tetanus are both forms of generalised tetanus (the most common manifestation of the disease - see Presentation, above) and have similar courses. About 90% of neonates with tetanus develop symptoms in the first 3-14 days of life (mostly on days 6-8), which separates it from other causes of neonatal mortality that more commonly occur in the first 2 days of life.
In newborn babies, sepsis can accompany tetanus, exacerbating the severity of illness. The hospital course of tetanus patients who survive is often protracted and complicated by pneumonia or other nosocomial infections.
Neonatal tetanus mortality approached 100% in community-based surveys in the 1980s, but is now 10-60% with hospital care. Maternal tetanus has been associated with higher mortality, in some series, than adult tetanus associated with other types of wounds. Women with tetanus after abortion seem to have especially high mortality, perhaps because they might delay seeking medical care until later in their disease.
Further reading & references
- Dire DJ; Tetanus, eMedicine, March 2009.
- Immunizations - childhood vaccination programme, Clinical Knowledge Summaries (February 2008)
- Immunizations - travel vaccinations, Clinical Knowledge Summaries (2007)
- Notifications of Infectious Diseases (NOIDs), Health Protection Agency
- Oladiran I, Meier DE, Ojelade AA, et al; Tetanus: continuing problem in the developing world. World J Surg. 2002 Oct;26(10):1282-5. Epub 2002 Sep 6.
- Meegan ME, Conroy RM, Lengeny SO, et al; Effect on neonatal tetanus mortality after a culturally-based health promotion programme. Lancet. 2001 Aug 25;358(9282):640-1.
- Tolan RW, Ray S; Tetanus, eMedicine, Jan 2009.
- Immunisation against infectious disease - the Green Book; Dept of Health (latest edition)
- Anuradha S; Tetanus in adults--a continuing problem: an analysis of 217 patients over 3 years from Delhi, India, with special emphasis on predictors of mortality. Med J Malaysia. 2006 Mar;61(1):7-14.
- Roper MH, Vandelaer JH, Gasse FL; Maternal and neonatal tetanus. Lancet. 2007 Dec 8;370(9603):1947-59.
|Original Author: Dr Hayley Willacy||Current Version: Dr Hayley Willacy|
|Last Checked: 25/08/2010||Document ID: 2845 Version: 24||© EMIS|
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