Vaccine Preventable Diseases and Vaccination Coverage in Australia, 2003 to 2005

Tetanus

Disclaimer: This is the fourth report on vaccine preventable disease and vaccination coverage in Australia, and is produced by the National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases and the Australian Institute of Health and Welfare on behalf of the Australian Government Department of Health and Ageing published as a supplement to the Communicable Diseases Intelligence journal Volume 31, June 2007.

Page last updated: 20 July 2007

Tetanus is a disease induced by an exotoxin of the Clostridium tetani bacterium, which grows anaerobically at the site of an injury. The disease is characterised by painful muscle contractions, primarily of the masseter and neck muscles, secondarily of the trunk muscles. The case-fatality rate ranges from 10% to 90%, with the highest rates in infants and the elderly.44

Case definition

See Appendix 6 for pre 2004 definition

National definition from January 2004:11

Confirmed cases require either laboratory definitive evidence or clinical evidence.

a) Laboratory definitive evidence

  • Isolation of Clostridium tetani from a wound in a compatible clinical setting and prevention of positive tetanospasm in mouse test from such an isolate using specific tetanus antitoxin.

b) Clinical evidence

  • A clinically compatible illness without apparent cause
Hospitalisations and deaths

The ICD-10-AM/ICD-10 codes A34 (obstetrical tetanus) and A35 (other tetanus) were used to identify hospitalisations and deaths.

Secular trends

There were 11 notifications of tetanus in the January 2003 to December 2005 review period (an average annual notification rate of 0.02 per 100,000). However, in the period July 2002 to June 2005, there were 66 hospitalisations coded as tetanus (an average annual rate of 0.11 per 100,000). Notifications for tetanus remained relatively stable between 2002 and 2005, ranging from two to five notifications annually. Hospitalisations for tetanus declined between 2002/2003 and 2004/2005 (Figure 44).

Figure 44. Tetanus notifications and hospitalisations, Australia, 1993 to 2005,* by year of diagnosis or admission

Figure 44. Tetanus  notifications and hospitalisations, Australia, 1993 to 2005, by year of  diagnosis or admission

* Notifications where the year of diagnosis was between January 1993 and December 2005;
hospitalisations where the month of admission was between 1 July 1993 and 30 June 2005.

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Severe morbidity and mortality

A total of 1,061 hospital bed days (average 354 per year) were recorded for patients with an ICD-10-AM code for tetanus. Of the 66 separations, 46 (70%) had tetanus recorded as the principal diagnosis. The median length of stay in hospital was 4.5 days and varied depending on age. Adults aged 60 years and over had longer median lengths of stay (Table 22).

Table 22. Tetanus notifications, hospitalisations and deaths, Australia, 2002 to 2005,* by age group

Age group
(years)
Notifications
3 years
(2003–2005)
Hospitalisations
3 years
(July 2002–June 2005)
LOS per admission
(days)
Deaths
2 years
(2003–2004)
n Rate n (§) Rate (§) Median (§) n Rate
0–4
0
0.00
0
(0)
0.00
(0.00)
0.0 (0.0)
0
0.00
5–14
0
0.00
1
(1)
0.01
(0.01)
n.p.
0
0.00
15–24
0
0.00
6
(4)
0.07
(0.05)
1.0 (1.0)
0
0.00
25–59
0
0.00
15
(9)
0.05
(0.03)
2.0 (2.0)
0
0.00
60+
11
0.10
44
(32)
0.43
(0.31)
12.0 (10.0)
0
0.00
All ages
11
0.02
66
(46)
0.11
(0.08)
4.5 (3.5)
0
0.00

* Notifications where the month of diagnosis was between January 2003 and December 2005; hospitalisations where the month of separation was between 1 July 2002 and 30 June 2005; deaths where the death was recorded in 2003 or 2004.

† LOS = length of stay in hospital.

‡ Average annual age-specific rate per 100,000 population.

§ Principal diagnosis (hospitalisations).

n.p. Not published due to small cell size.

In the review period (2003–2004), there were no deaths in the AIHW mortality database with tetanus recorded as the underlying cause. However, there was one death (in 2004) amongst notified cases reported to NNDSS for the period 2003–2005.

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Age and sex distribution

All of the notified case patients and the majority of the hospitalised patients (44/66, 67%) were aged 60 years and over. The youngest hospitalised case was a child aged 5–14 years. The male:female ratio of notified cases was 0.84:1, but there were fewer hospitalised female patients, with a male:female ratio of 1.2:1. In the age group 70 years and over, 66% of the hospitalised cases (23/35) were males.

For both notifications and hospitalisations, rates increased with increasing age (Figure 45). Males aged 70 years and over had the highest average annual hospitalisation rate (0.98 per 100,000).

Geographical distribution

Notification and hospitalisation rates varied over time and between states and territories (Appendices 2 and 3). However, there were too few cases in each jurisdiction to identify any trends.

Figure 45. Tetanus notification and hospitalisation rates, Australia, 2003 to 2005,* by age group

Figure 45. Tetanus  notification and hospitalisation rates, Australia, 2003 to 2005, by age  group

* Notifications where the month of diagnosis was between January 2003 and December 2005; hospitalisations where the month of separation was between 1 July 2002 and 30 June 2005.

Vaccination status

The vaccination status of 73% (8/11) of notified cases in NNDSS was “unknown” in 2003–2005. No case was reported as fully vaccinated.

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Comment

There has been a downward trend in tetanus hospitalisation rates. Hospitalisation rates remain higher for tetanus than notification rates. It is likely that this discrepancy is principally due to under-reporting, together with multiple hospital admissions for the same case and coding errors.261 Coding errors may have resulted from misclassification of other conditions as tetanus, especially where tetanus was not the principal diagnosis. Notifications of tetanus rely heavily on clinicians rather than laboratories, as laboratory confirmation of the diagnosis is rarely possible. Clinicians are known to under-notify hospitalised cases of disease;19 thus, under-notification for tetanus is likely.

Tetanus is a disease of older adults. In Australia, booster doses of tetanus vaccine are thought to be poorly utilised, as noted in Canada and Switzerland.262,263 The major impetus for tetanus immunisation in adults is injury,262 but tetanus occurs in cases with trivial or no known injury and the definition of a ‘tetanus prone’ wound is unclear.264,265 International serosurveys and the Australian National Serosurvey have shown progressively lower prevalence of levels of tetanus antibody in older age groups, particularly in women.58,266–269 Although the tetanus organism is ubiquitous in the environment, and the vaccine only provides individual level protection against the toxin, tetanus vaccination programs have had a significant impact upon the disease burden in Australia. The current tetanus notification rate in Australia is similar to that in other developed countries.264,270–272 A tetanus booster is recommended at the age of 50 unless a booster has been documented within 10 years.76 Whilst the data presented in this report suggest that this is an appropriate recommendation, strategies to improve vaccine uptake at this age need to be investigated. As both notifications and hospitalisations predominate in those aged 65 years and over, review of tetanus immunisation status at the time of annual influenza vaccination is clearly appropriate. Young and middle-aged people have been the focus of a recent tetanus outbreak amongst intravenous drug users in the United Kingdom and also comprise an increasing proportion of notifications in the United States.271,273 Therefore, maintenance of immunity in young adults, through the scheduled booster dose at age 15–17 years, is also important.

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