Vaccine Preventable Diseases and Vaccination Coverage in Aboriginal and Torres Strait Islander People, Australia, 2003 to 2006

Measles

Disclaimer: 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 32, June 2008.

Page last updated: 30 June 2008

Measles is an acute and highly communicable disease caused by a morbillivirus. The clinical picture primarily includes prodromal fever and Koplik spots on the buccal mucosa, rash, and often conjunctivitis, coryza and cough. Complications include otitis media, pneumonia and encephalitis. Subacute sclerosing panencephalitis (SSPE) occurs very rarely as a late sequela of wild infection but not vaccination.36

Case definitions


Notifications

National definition from January 2004:10

Isolation of measles virus (confirmed case); or

Detection of measles virus by nucleic acid testing (confirmed case); or

Detection of measles virus antigen (confirmed case); or

Measles virus-specific IgG seroconversion or significant increase in IgG antibody level or a fourfold or greater rise in antibody titre to measles virus, with paired sera tested in parallel and in the absence of receipt of measles-containing vaccine eight days to eight weeks prior to testing (confirmed case); or

Detection of measles virus-specific IgM antibody confirmed in an approved reference laboratory, in the absence of recent measles-containing vaccination (confirmed case); or

A clinical illness characterised by a generalised maculopapular rash lasting at least three days, fever of at least 38░C at the time of rash onset and either cough, coryza, conjunctivitis or Koplik spots, together with an epidemiological link to a confirmed case (confirmed case); or

A clinical illness as in point (f) above, together with detection of measles-specific IgM antibody other than by an approved reference laboratory (in the absence of recent measles-containing vaccination) (probable case).

(See Appendix D for pre-2004 definition)

Hospitalisations and deaths

The ICD-10-AM/ICD-10 code B05 (measles) was used to identify hospitalisations and deaths. SSPE was not included in these analyses.

áDistribution by Indigenous status

Of the total 246 measles notifications recorded in New South Wales, the Northern Territory, South Australia, Victoria and Western Australia over the four years from 2003 to 2006, 9 (4%) were identified as occurring in Aboriginal and Torres Strait Islander people (Table 7). For hospitalisations, 4 (7%) of the total 55 measles cases were identified as Aboriginal and Torres Strait Islander in the three-year period July 2002 to June 2005 in New South Wales, the Northern Territory, Queensland, South Australia and Western Australia (Table 8).

The overall Indigenous to non-Indigenous rate ratio was 0.6:1 for notifications and 2.0:1 for hospitalisations, neither ratio being statistically significantly different to 1.0 (Table 7 and Table 8).

Table 7. Measles notification rates, selected Australian states, 2003 to 2006, by age group and Indigenous status

Age group
(years)
Indigenous status
Notifications*
(2003–2006)
n Rate Rate ratio
All ages Indigenous
9
0.6
1.4
Other
237
0.4

* Notifications (New South Wales, the Northern Territory, South Australia, Victoria and Western Australia only) where the date of diagnosis was between 1 January 2003 and 31 December 2006.

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

‡ Rates for all ages combined are age-standardised to the Australian Bureau of Statistics Australian population estimates for 2005.

Shaded cells indicate statistically significant, 95% confidence intervals greater than 1 (p<0.5).

Table 8. Measles hospitalisations and deaths, selected Australian states, 2002 to 2005, for all ages combined, by Indigenous status

Age group
(years)
Indigenous status
Hospitalisations*
(July 2002–June 2005)
Deaths
2003–2005
n Rate Rate ratio n
All ages§ Indigenous
4
0.2
2.0
0
Other
51
0.1
0

* Hospitalisations (New South Wales, the Northern Territory, Queensland, South Australia and Western Australia only) where the date of separation was between 1 July 2002 and 30 June 2005.

† Deaths (the Northern Territory, Queensland, South Australia and Western Australia only) where the death was recorded between 1 January 2003 and 31 December 2005.

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

§ Includes cases with unknown ages. Rates for all ages combined are age-standardised to the Australian Bureau of Statistics Australian population estimates for 2005.

Shaded cells indicate statistically significant, 95% confidence intervals greater than 1 (p<0.5).

No time series analysis of hospitalisations was conducted due to the small numbers.

One adult death was recorded from measles in the Northern Territory, Queensland, South Australia and Western Australia for the three years 2003 to 2005. However, on further investigation this was found to be due to subacute sclerosing panencephalitis, a rare sequela of childhood infection, and was not reported here.5

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Comment

Measles vaccination was recommended for all Australian children at 12 months and 4 years of age for the period covered in this report. Epidemics of measles continued to occur in Australia for several decades after the introduction of vaccination in 1969.5 Measles was associated with higher levels of morbidity, and some deaths, among Aboriginal and Torres Strait Islander children, prompting the Northern Territory in 1984 to immunise Aboriginal and Torres Strait Islander infants at 9 months of age, with a subsequent booster.61 This program ended in 1998,62 the year of the national Measles Control Campaign, which involved catch-up immunisation of 1.3 million children aged 5–12 years, and the moving of the second dose of measles-mumps-rubella (MMR) vaccine from 12 to 4 years of age.63

Measles notifications and hospitalisations are now at record lows in Australia, dominated by limited local outbreaks, mainly among young adults who were born at a time when vaccination coverage was low, and triggered by cases acquired overseas.5 No excess morbidity from measles in Aboriginal and Torres Strait Islander people is evident in data presented in this report, or the previous report covering 1999 to 2002.1

The successful control of measles in Aboriginal and Torres Strait Islander people is a reflection of the almost total success of immunisation in preventing measles transmission, in contrast to other VPDs such as pertussis or Hib disease. It illustrates the importance of universal programs, across all relevant age groups in the population, in disease prevention in both Indigenous and non-Indigenous people.

Universal measles vaccination has successfully controlled measles in Australia, including amongst Aboriginal and Torres Strait Islander people.