This article {extract} was published in Communicable Diseases Intelligence Vol 34 No 3 September 2010 and may be downloaded as a full version PDF from the Table of contents page.

Methods

Australia is a federation of 6 states (New South Wales, Queensland, South Australia, Tasmania, Victoria and Western Australia) and 2 territories (the Australian Capital Territory and the Northern Territory).

State and territory health departments collect notifications of communicable diseases under their public health legislation. In September 2007, the National Health Security Act 2007¹ received royal assent. This Act provides a legislative basis for and authorises the exchange of health information, including personal information, between jurisdictions and the Commonwealth. The Act provides for the establishment of the National Notifiable Diseases List,² which specifies the diseases for which personal information can be shared. The National Health Security Agreement 2008³ establishes operational arrangements to formalise and enhance existing surveillance and reporting systems, an important objective of the Agreement.

Under the Agreement, in 2008 states and territories forwarded de-identified data on the nationally agreed set of 65 communicable diseases to the Department of Health and Aging for the purposes of national communicable disease surveillance, although not all 65 diseases were notifiable in each jurisdiction. States and territories provided data to the National Notifiable Diseases Surveillance System (NNDSS) electronically, daily or several times a week. The system was complemented by other surveillance systems, which provided information on various diseases, including four that are not reported to NNDSS, namely human immunodeficiency virus (HIV), acquired immune deficiency (AIDS) and the classical and variant forms of Creutzfeldt-Jakob disease (CJD).

In 2008, the NNDSS core dataset included the following 5 mandatory data fields: unique record reference number; notifying state or territory; disease code; confirmation status and the date when the public health unit was notified (notification receive date). In addition, the following core but non-mandatory data fields were supplied where possible: date of birth; age at onset; sex; indigenous status; postcode of residence; disease onset date; date when the medical practitioner signed the notification form (notification date), death status, date of specimen collection and outbreak reference number (to identify cases linked to an outbreak). Where relevant, information on the species, serogroups/subtypes and phage types of organisms isolated, and on the vaccination status of the case were collected and reported to NNDSS. Data quality was monitored by the Office of Health Protection and the National Surveillance Committee (NSC) and there was a continual process of improving the national consistency of communicable disease surveillance through the daily, fortnightly and quarterly review of these data.

While not included in the core national dataset, enhanced surveillance information for some diseases (invasive pneumococcal disease, hepatitis C, tuberculosis and some sexually transmissible infections) were reported from states and territories to NNDSS but not included in this report. Additional information concerning mortality and specific health risk factors for some diseases were obtained from states and territories and included in this annual report.

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Newly diagnosed HIV infection and AIDS were notifiable conditions in each state or territory health jurisdiction in 2008 and these data were forwarded directly to the National HIV Registry and National AIDS Registry at the National Centre in HIV Epidemiology and Clinical Research (NCHECR). Further information can be found in NCHECR's annual surveillance report.⁴

Surveillance of the classical and variant forms of CJD in Australia has been conducted through the Australian National Creutzfeldt-Jakob Disease Registry (ANCJDR) since its establishment in October 2003. CJD is a nationally notifiable disease and by June 2006, CJD was notifiable in all states and territories. Further surveillance information on CJD can be found in surveillance reports from the ANCJDR.⁵

Information from communicable disease surveillance is communicated through several avenues. The most up-to-date information on topics of interest is provided at fortnightly teleconferences of the Communicable Diseases Network Australia (CDNA) and a summary of these reports is available online from http://www.health.gov.au/cdnareport⁶ The Communicable Diseases Intelligence (CDI) quarterly journal publishes surveillance data and reports of research studies on the epidemiology and control of various communicable diseases.

Notification rates for each notifiable disease were calculated using the estimated 2008 mid-year resident population supplied by the Australian Bureau of Statistics⁷ (ABS) (Appendix 1 and Appendix 2). Where diseases were not notifiable in a state or territory, national rates were adjusted by excluding the population of that jurisdiction from the denominator. For some diseases, age adjusted rates were calculated using either the direct method of standardisation for gastrointestinal diseases, or indirect method for sexually transmissible infections, with 2006 census data as the standard population.

The 4 maps produced for this report (chlamydia, influenza, pertussis, Q fever) were created with ArcGIS mapping software (ESRI, Redlands, CA) and based on the NNDSS notifications' residential postcode recorded in the NNDSS.

With one exception, maps were based on Statistical Divisions (SDs), as defined by the Australian Standard Geographical Classification (AGSC) (Map 1, Table 1), for all states and territories. The Northern Territory was represented by Statistical Subdivisions (SSD) and in the case of Greater Darwin, by the combination of the Tiwi Islands, Darwin, Palmerston and Litchfield SSD. This combination helped preserve confidentiality while improving legibility at the scale the maps to be printed. The geocode 77777 for Greater Darwin is only nominal.

Map 1: Australian Bureau of Statistics Statistical Division codes, Australia, and Statistical Subdivision codes, Northern Territory, 2008

Table 1: Australian population by Statistical Division and Statistical Subdivision for the Northern Territory, 2008

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SD code	Statistical Division	Population	SD code	Statistical Division	Population
Australian Capital Territory			South Australia
805	Canberra	345,257	405	Adelaide	1,172,105
810	ACT balance	294	410	Outer Adelaide	134,085
New South Wales			415	Yorke and Lower North	46,396
105	Sydney	4,399,722	420	Murray Lands	70,125
110	Hunter	632,851	425	South East	65,402
115	Illawarra	423,487	430	Eyre	35,174
120	Richmond–Tweed	237,361	435	Northern	80,074
125	Mid-North Coast	304,323	Tasmania
130	Northern	181,667	605	Greater Hobart	209,287
135	North Western	116,736	610	Southern	36,875
140	Central West	180,074	615	Northern	140,275
145	South Eastern	212,238	620	Mersey–Lyell	111,092
150	Murrumbidgee	155,868	Victoria
155	Murray	117,108	205	Melbourne	3,892,419
160	Far West	22,737	210	Barwon	278,668
Northern Territory (Subdivisions)			215	Western District	104,709
71005	Finniss	2,214	220	Central Highlands	152,075
71010	Bathurst–Melville	2,501	225	Wimmera	50,404
71015	Alligator	6,913	230	Mallee	93,568
71020	Daly	4,353	235	Loddon	179,948
71025	East Arnhem	16,077	240	Goulburn	207,685
71030	Lower Top End NT	18,894	245	Ovens–Murray	98,250
71040	Central NT	40,299	250	East Gippsland	85,318
77777	Greater Darwin	123,139	255	Gippsland	170,779
Queensland			Western Australia
305	Brisbane	1,945,639	505	Perth	1,602,559
307	Gold Coast	497,848	510	South West	236,058
309	Sunshine Coast	312,804	515	Lower Great Southern	57,439
312	West Moreton	90,738	520	Upper Great Southern	18,887
315	Wide Bay–Burnett	277,965	525	Midlands	54,603
320	Darling Downs	231,599	530	South Eastern	58,074
325	South West	26,150	535	Central	63,409
330	Fitzroy	214,753	540	Pilbara	45,983
335	Central West	12,256	545	Kimberley	34,185
340	Mackay	167,666	Other territories		–
345	Northern	220,656	Total		21,423,938
350	Far North	262,095
355	North West	33,746

Source: ABS 3218.0 Regional Population Growth, Australia, 23 April 2009 (http://abs.gov.au/AUSSTATS/abs@.nsf/DetailsPage/3218.02007–08).

Notifications were summed by the postcode weighting calculated by the Australian Bureau of Statistics Postcode Concordance.⁸ These ABS concordance data were used to proportionally allocate notifications into SDs/SSDs according to the percentage of the population of the postcode living in the region. The total notifications per region are displayed in the relevant area.

Disease rates were calculated per 100,000 population for the relevant areas using ABS population data.⁷ Rates were mapped for different SDs and ordered into 5 groups using the Jenks Natural Breaks method (http://resources.arcgis.com/content/kbase?fa=articleShow&d=26442) whereby the largest breaks between natural clusters of ordered data were identified and used as class boundaries. A class '0' was added to account for areas with no notifications, resulting in a total of 6 rate classes per map. Note that the classification is data dependent and changes from map to map.