Tetanus

Victorian statutory requirement

Tetanus (Group B disease) must be notified in writing within five days of diagnosis.

School exclusion is not applicable.

Infectious agent

Clostridium tetani, the tetanus bacillus is the causative agent.

Identification

Clinical features
Tetanus is an acute, potentially fatal disease caused by tetanus bacilli multiplying at the site of an injury. These produce an exotoxin that reaches the central nervous system and causes muscle stimulation.

Initial features are increased muscle rigidity. This may be restricted to and most pronounced in muscles near the injury (localised tetanus). Depending on severity, muscle rigidity usually affects most parts of the body and is associated with hyperreflexia. As a result, features such as neck, back and limb stiffness, stiff jaw or ‘lock jaw’ (trismus) and a sardonic smile (risus sardonicus) may occur.

With progression, superimposed painful muscle spasms can appear anywhere or involve most body muscles simultaneously. Opisthotonos can result. This is when spasm is most marked in the back muscles causing the head and heels to bend backward and the body to bow forward. Painful spasms may become very frequent and together with background rigidity cause life-threatening interference with respiration.

Laryngeal spasm is a very serious complication which may occur at any stage and can cause sudden asphyxia. Exhaustion and inability to swallow are also associated with severe disease.

Case fatality rates vary from 10–90% and are highest in infants and the elderly.

Method of diagnosis
Clinical features of severe classical tetanus are virtually diagnostic.

Laboratory confirmation of tetanus infection is often difficult. C. tetani antibodies are sometimes detectable in serum samples but may result from waning past immunisation. Cultures from the site of infection should be attempted although the organism is often not recovered.

Incubation period

The incubation period is usually three to 21 days although it may range from one day to several months depending upon the nature of exposure. Most cases occur within14 days.
Cases with shorter incubation periods tend to have more severe disease and thereby a greater risk of death.

Public health significance & occurrence

Tetanus occurs worldwide but is now rare in developed countries due to high immunisation rates. Infection is most likely in older people who have never been immunised or who have waning and inadequate immunity.

Tetanus is still common in developing countries with low immunisation rates and where contact with animal excreta is more common. Tetanus, particularly neonatal tetanus, is a significant cause of death in these settings.

Intravenous drug use is an independent risk factor for tetanus in the absence of acute injuries and may be linked to localised case clusters.

Reservoir

C. tetani is widely distributed in cultivated soil and in the gut of humans and animals. Spores can usually be found wherever there is contamination with soil.

Mode of transmission

Tetanus is not directly transmitted from person to person.

Spores may be introduced through contaminated puncture wounds, lacerations, burns or contaminated injected ‘street drugs’. Tetanus can result from minor wounds considered too trivial for medical consultation.

The presence of necrotic tissue or foreign bodies encourages the growth of anaerobic organism such as C. tetani. Tetanus rarely follows surgical procedures today.

Period of communicability

Spores may remain viable for many years in the environment.

Susceptibility & resistance

Active immunity is produced by immunisation with tetanus toxoid and persists for at least ten years after full immunisation.

Transient passive immunity follows injection of tetanus immune globulin (TIG) or tetanus antitoxin.

Recovery from tetanus is not necessarily associated with immunity.

Control measures

Preventive measures
Tetanus toxoid is part of the Australian Standard Vaccination Schedule. Primary immunisation for children begins at two months of age and requires three doses of tetanus toxoid-containing vaccine at two-monthly intervals. Children should be given a booster at four years of age. A further booster dose is given prior to leaving school (15–17 years of age) and again at 50 years of age.

For further information on tetanus vaccination, particularly with respect to the management of children who have missed doses, consult the current edition of The Australian immunisation handbook (National Health and Medical Research Council).

The use of tetanus toxoid in the management of wounds, with or without tetanus immunoglobulin, is determined by considering the vaccination history of the person and the nature of the wound. For further information on the management of bites and other tetanus-prone wounds, consult the current edition of Therapeutic guidelines: antibiotic (Therapeutic Guidelines Limited).

Control of case
Refer the patient immediately to a specialised centre with intensive care facilities. The principles of treatment include:

tetanus immunoglobulin (TIG) by intramuscular injection
IV penicillin in large doses for 10 to 14 days. Intravenous metronidazole is a reasonable alternative for patients with immediate penicillin hypersensitivity
adequate wound debridement
careful attention to provide an adequate airway and to control muscle spasm
case investigation to determine the circumstances of injury
completion of course of active immunisation after recovery.

Control of contacts
Not required.

Control of environment
Not required.

Outbreak measures

Not applicable.

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