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

Meningococcal disease

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

Meningococcal disease is defined as isolation of Neisseria meningitidis from cerebrospinal fluid (CSF), blood and other normally sterile sites, as well as skin lesions. Clinical manifestations include meningitis, meningococcaemia without meningitis (which varies in presentation from fulminant to chronic), meningitis and meningococcaemia combined, and septic arthritis.

Case definitions


Notifications

National definition from January 2004:10

Confirmed cases require either laboratory definitive evidence or laboratory suggestive evidence and clinical evidence. Probable cases require specified clinical evidence only (as below) and are also notifiable.

Laboratory definitive evidence

Isolation of Neisseria meningitidis from a normally sterile site.

Laboratory suggestive evidence

Detection of meningococcus from a normally sterile site by nucleic acid testing; or

Detection of Gram-negative diplococci in Gram stain of specimen from a normally sterile site or from a suspicious skin lesion; or

High titre IgM or significant rise in IgM or IgG titres to outer membrane protein antigens of N. meningitidis; or

Positive polysaccharide antigen test in cerebrospinal fluid with other laboratory parameters consistent with meningitis.

Clinical evidence (for confirmed cases with laboratory suggestive evidence)

Disease which, in the opinion of the treating clinician, is compatible with invasive meningococcal disease.

Clinical evidence for notification of probable cases

The absence of evidence for other causes of clinical symptoms and either

Clinically compatible disease including haemorrhagic rash; or

Clinically compatible disease AND close contact with a confirmed case within the previous 60 days.

(See Appendix D for pre-2004 definition)

Hospitalisations and deaths

The ICD-10-AM code used to identify hospitalisations and deaths was A39 (meningococcal infection). This includes meningococcal meningitis (A39.0), Waterhouse-Friderichsen syndrome (A39.1), acute meningococcaemia (A39.2), chronic meningococcaemia (A39.3), meningococcaemia unspecified (A39.4), meningococcal heart disease (A39.5), other meningococcal infections (A39.8), and meningococcal infection unspecified (A39.9).

Top of page 

Distribution by Indigenous status and age

Of the total 1,263 notifications of meningococcal disease recorded in New South Wales, the Northern Territory, South Australia, Victoria and Western Australia over the four years from 2003 to 2006, 106 (8%) were identified as occurring in Aboriginal and Torres Strait Islander people (Table 9). For hospitalisations, 117 (8%) of the total 1,507 cases were in people 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 10).

Incidence was highest in 0–4 year olds for Indigenous and presumed non-Indigenous people. There was a smaller peak at age 15–24 years for non-Indigenous people and 25–49 years for Indigenous people (Table 9 and Table 10, Figure 8).

Figure 8. Meningococcal notification rates, selected Australian states,* 2003 to 2006, by age group and Indigenous status

Figure 8. Meningococcal notification rates, selected Australian states, 2003 to 2006, by age group and Indigenous status

* New South Wales, the Northern Territory, South Australia, Victoria and Western Australia.

† Notifications where the date of diagnosis was between 1 January 2003 and 31 December 2006.

The overall Indigenous to non-Indigenous rate ratio was 2.6:1 for notifications and 1.7:1 for hospitalisations, and both ratios were statistically significantly above 1.0. The Indigenous to non-Indigenous notification rate ratios were significantly above 1.0 for age groups 0–4, 5–14, and 25–49 years (Table 9) and, for hospitalisations, in age groups 0–4 and 25–49 years (Table 10).

Of the 21 deaths recorded from meningococcal disease in the Northern Territory, Queensland, South Australia and Western Australia, one was recorded as Aboriginal and Torres Strait Islander (Table 10).

Table 9. Meningococcal 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
0–4 Indigenous
73
44.9
4.9||
Other
337
9.2
5–14 Indigenous
14
4.3
2.5||
Other
133
1.7
15–24 Indigenous
4
1.5
0.4
Other
318
3.8
25–49 Indigenous
13
3.0
3.5||
Other
189
0.9
50+ Indigenous
2
1.4
1.4
Other
180
1.0
All ages Indigenous
106
5.1
2.6||
Other
1,157
1.9

* 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 10. Meningococcal hospitalisations and deaths, selected Australian states, 2002 to 2005, by age group and Indigenous status

Age group
(years)
Indigenous status
Hospitalisations*
(July 2002–June 2005)
Deaths†
2003–2005
n Rate Rate ratio n
0–4 Indigenous
74
45.4
2.7||
0
Other
425
16.6
4
5–14 Indigenous
17
5.2
1.3
0
Other
215
3.9
0
15–24 Indigenous
12
4.6
0.7
0
Other
364
6.3
7
25–49 Indigenous
11
2.6
2.1||
0
Other
187
1.2
6
50+ Indigenous
3
2.1
1.4
0
Other
199
1.5
2
All ages§ Indigenous
117
5.8
1.7||
1
Other
1,390
3.3
21

* 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).

Serogroup was recorded for 738 (59%) of the 1,263 notifications. For cases recorded as Aboriginal and Torres Strait Islander, meningococcal serogroup B was identified in 79 (89%) and serogroup C in 8 (9%), and other serogroups in 2%, compared with 71%, 22% and 7%, respectively, for presumed non-Indigenous cases (Chi sq. p= 0.001).

Over the six-year period July 1999 to June 2005, hospitalisation rates for meningococcal disease were higher for Indigenous people compared with people presumed to be non-Indigenous in years 2001/2002, 2003/2004 and 2004/2005 (Figure 9). A significant decline in rates in non-Indigenous people corresponded to the start of universal meningococcal C vaccination in 2003. The decline in rates in Aboriginal and Torres Strait Islander people over this period was more variable and not statistically significant.

Figure 9. Meningococcal hospitalisation rates, selected Australian states,* 1999 to 2005, by Indigenous status

Figure 9. Meningococcal hospitalisation rates, selected Australian states, 1999 to 2005, by Indigenous status

* The Northern Territory, Queensland, South Australia and Western Australia.

† Hospitalisations where the date of separation was between 1 July 1999 and 30 June 2005. Rates are age-standardised to the Australian Bureau of Statistics Australian population estimates for 2005.

Top of page

Comment

The national meningococcal C vaccination program provided vaccine for all infants at 12 months of age from 2003 and a catch-up program for all aged up to 19 years.20 Prior to that, only polysaccharide vaccines targeting serogroups A, C, Y and W135 were available, used for the control of outbreaks and for travellers to high incidence countries. The relative distributions of different meningococcal serogroups vary over time and between jurisdictions, due to a range of factors including the emergence or importation of previously unknown serotypes.64 Historically, the incidence of meningococcal disease has been disproportionately higher among Aboriginal and Torres Strait Islander Australians, with well-recorded outbreaks in Central Australia65 and north-west Queensland66 due to serogroup A and serogroup C disease. The current pattern is of predominantly sporadic serogroup B disease in young children, similar to that seen in Maori and Pacific Islander children in New Zealand,67 in whom living conditions have been shown to be an important disease risk factor.68 The apparently smaller impact of the national meningococcal C program in Indigenous compared with non-Indigenous people in the hospitalisation data presented here is consistent with the smaller proportion of cases being due to serogroup C in Indigenous people before the program started. Vaccines protecting against all subtypes of serogroup B disease could make an important contribution to decreasing the disparity between Indigenous and non-Indigenous people in the incidence of meningococcal disease. The vaccine against one serogroup B subtype that has been used so successfully in New Zealand69 does not provide sufficient coverage of Australian subtypes. While work on developing other vaccines continues, a commercially available vaccine against a broad range of B disease is still some way off.70

Aboriginal and Torres Strait Islander children less than 5 years of age have the highest recorded rates of meningococcal disease, almost five times the rate for non-Indigenous children. Meningococcal serogroup B disease accounted for nearly 90% of the Aboriginal and Torres Strait Islander cases and, hence, a vaccine for this serogroup will be important for decreasing this disparity.