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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 respective 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 about which personal information can be provided. The National Health Security Agreement,³ which was drafted in 2007 and signed by Health Ministers in April 2008, establishes operational arrangements to formalise and enhance existing surveillance and reporting systems, an important objective of the Act. Under the Agreement, in 2010 states and territories forwarded de-identified data on the nationally agreed set of 65 communicable diseases to the Department of Health and Ageing for the purposes of national communicable disease surveillance, although not all 65 diseases were notifiable in each jurisdiction. Data were renewed electronically from states and territories, daily or several times a week.

In 2010, the National Notifiable Diseases Surveillance System (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 central agency in the jurisdiction 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 B, 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.

Newly diagnosed HIV infection and AIDS were notifiable conditions in each state or territory health jurisdiction in 2010 and were forwarded to the Kirby Institute for infection and immunity in society. Further information can be found in the Kirby Institute’s annual surveillance report.⁴

The surveillance for the classical and variant forms of Creutzfeldt-Jakob disease (CJD) in Australia is 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 2010 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 the direct method of standardisation. for gastrointestinal diseases, or indirect method for sexually transmissible infections, with 2006 census data as the standard population. All rates are represented as the rate per 100,000 population unless stated otherwise.

The 2 maps produced for this report (chlamydia and pertussis) were created with ArcGIS mapping software (ESRI, Redlands, CA) and based on the NNDSS notifications’ residential postcode. Notifications were summed by the postcode weighting calculated by the ABS 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.

With one exception, all jurisdictions in the Australian map consist of Statistical Divisions (SD) as defined by the Australian Standard Geographical Classification (Map 1, Table 1). 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 SSDs. This combination helps preserve confidentiality while improving legibility at the scale of 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, 2010

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Table 1: Australian population by Statistical Division and Statistical Subdivision for the Northern Territory, 2009

SD code	Statistical Division	Population	SD code	Statistical Division	Population
Australian Capital Territory			South Australia
805	Canberra	351,868	405	Adelaide	1,203,186
810	ACT balance	Included above	410	Outer Adelaide	139,489
New South Wales			415	Yorke and Lower North	47,585
105	Sydney	4,575,532	420	Murray Lands	70,705
110	Hunter	651,622	425	South East	66,724
115	Illawarra	436,117	430	Eyre	35,892
120	Richmond–Tweed	244,085	435	Northern	81,001
125	Mid-North Coast	313,322	Tasmania
130	Northern	186,496	605	Greater Hobart	214,705
135	North Western	119,329	610	Southern	37,838
140	Central West	184,921	615	Northern	142,311
145	South Eastern	219,655	620	Mersey–Lyell	112,789
150	Murrumbidgee	159,624	Victoria
155	Murray	119,302	205	Melbourne	4,077,036
160	Far West	22,584	210	Barwon	290,277
Northern Territory (Subdivisions)			215	Western District	107,072
71005	Finniss	2,906	220	Central Highlands	158,627
71015	Alligator	6,908	225	Wimmera	50,903
71025	East Arnhem	16,252	230	Mallee	95,213
71030	Lower Top End NT	24,170	235	Loddon	186,201
71035	Barkly	8,137	240	Goulburn	212,799
71040	Central NT	41,272	245	Ovens–Murray	101,086
77777	Greater Darwin	130,066	250	East Gippsland	87,872
Queensland			255	Gippsland	178,846
305	Brisbane	2,043,185	Western Australia
307	Gold Coast	527,828	505	Perth	1,696,065
309	Sunshine Coast	330,934	510	South West	253,512
312	West Moreton	97,414	515	Lower Great Southern	59,412
315	Wide Bay–Burnett	293,455	520	Upper Great Southern	19,100
320	Darling Downs	241,537	525	Midlands	56,435
325	South West	26,489	530	South Eastern	59,070
330	Fitzroy	223,516	535	Central	65,600
335	Central West	12,387	540	Pilbara	48,610
340	Mackay	176,236	545	Kimberley	35,706
345	Northern	231,628	Other territories		–
350	Far North	275,058	Australia	Total	22,326,388
355	North West	34,183

Source: ABS 3235.0 Regional Population Growth, Australia, 4 August 2011.8

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 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, for a total of 6 rate classes per map. Note that the classification is data dependent and changes from map to map.