In 1997 there were 89,579 notifications to the National Notifiable Diseases Surveillance System. A notable feature of 1997 was the pertussis outbreak which peaked towards the end of the year and resulted in 10,668 cases being notified. The highest number of notifications received was for hepatitis C (unspecified) with 19,692 notifications; this is the first year for which data have been reported for New South Wales and South Australia for this disease category. The number of measles cases rose after the low number reported in 1996 but is still well below the number reported in the outbreak years of 1993 and 1994. Rubella notifications continued to decline in 1997. Notifications of Haemophilus influenzae type b appeared to have stabilised at a low rate, having declined markedly after introduction of the conjugated vaccine in 1992. The number of cases of campylobacteriosis remained steady after having risen for several years. Notifications of hepatitis A cases rose considerably, much of this being due to one outbreak in New South Wales. The number of cases of salmonellosis rose while shigellosis numbers dropped slightly. Notifications for chlamydial infection and gonococcal infection continued to rise, whilst those for syphilis continued to fall. Commun Dis Intell 1999;23:1-27.

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Introduction

Notification of communicable diseases is an important public health activity. It prompts investigation and the use of interventions to control the spread of diseases. Notification also enables the monitoring of the effectiveness of existing control activities. Many communicable disease control activities are conducted at local government or State level. This requires local and State-based surveillance. National surveillance combines data from the State and Territory-based systems. National surveillance is necessary for control activities in outbreaks which affect more than one jurisdiction, to monitor the need for, and impact of, national control programs and to guide national policy development. National surveillance also describes the epidemiology of rare diseases for which there are only a few notifications in each State. It also assists in quarantine activities and facilitates agreed international collaborations such as reporting to the World Health Organization.

The National Notifiable Diseases Surveillance System (NNDSS) was established in its current form in 1991, under the auspices of the Communicable Diseases Network Australia New Zealand (CDNANZ). The CDNANZ monitors the incidence of an agreed list of communicable diseases in Australia and New Zealand; only Australian data are regularly published in Communicable Diseases Intelligence (CDI) at this time. This is achieved through the national collation of notifications of these diseases received by health authorities of the States and Territories. More than forty diseases or disease categories are included, largely as recommended by the NHMRC.¹ Annual reports of the NNDSS have been published since 1991.^2,3,4,5,6,7

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Methods

Notifications of communicable diseases were collected during 1997 by the States and Territories under their public health legislations. These were collated and analysed fortnightly by the Department of Health and Aged Care and published to the Web fortnightly and in CDI every four weeks. Final data sets for cases reported in 1997 were provided by the States and Territories between June and November 1998. Missing data and apparent errors were corrected where possible, and duplicate records deleted, in consultation with the States and Territories. For the purposes of the NNDSS, where a patient being treated in one jurisdiction was diagnosed in another, notifications were made according to the State or Territory of the diagnosing medical practitioner.

The national data set included fields for: a unique record reference number; the disease; age, sex, Aboriginality; postcode of residence of the case; the date of onset of the disease and date of report to the State or Territory health authority; and the confirmation status of the report. Aboriginality was not included in the analyses due to incomplete reporting of this information.

Population notification rates were calculated using 1997 mid-year estimates of the resident population supplied by the Australian Bureau of Statistics. In cases where a disease was not notifiable in a State or Territory an adjusted rate was calculated using a denominator which excluded the population of that State or Territory. Maps were produced using postcode of residence of the case.

Population notification rates were calculated using 1997 mid-year estimates of the resident population supplied by the Australian Bureau of Statistics. In cases where a disease was not notifiable in a State or Territory an adjusted rate was calculated using a denominator which excluded the population of that State or Territory. Maps were produced using postcode of residence of the case.

Population notification rates were calculated using 1997 mid-year estimates of the resident population supplied by the Australian Bureau of Statistics. In cases where a disease was not notifiable in a State or Territory an adjusted rate was calculated using a denominator which excluded the population of that State or Territory. Maps were produced using postcode of residence of the case.

Population notification rates were calculated using 1997 mid-year estimates of the resident population supplied by the Australian Bureau of Statistics. In cases where a disease was not notifiable in a State or Territory an adjusted rate was calculated using a denominator which excluded the population of that State or Territory. Maps were produced using postcode of residence of the case.

Analyses were based on cases with report dates in 1997. The data included some notifications with onset dates before 1997, and excluded notifications with report dates in 1998 (even if the onset date was in 1997). For analysis of seasonal trends, notifications were reported by month of onset.

Notifications were allocated to the Australian Bureau of Statistics Statistical Divisions for mapping using postcodes of residence of the cases (Map 1). The two Statistical Divisions which make up the Australian Capital Territory were combined, as the population for one division is very small. Notifications for Darwin and the remainder of the Northern Territory were also combined to calculate rates for the Northern Territory as a whole. For South Australia, data for sexually transmissible diseases were combined for the whole state. In general, notification rates for Statistical Divisions were depicted in maps or discussed in the text only where the number of notifications was sufficiently large for these to be meaningful.

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Notes on interpretation

The notifications compiled by the NNDSS may be influenced by a number of factors which should be considered when interpreting the data. Due to under-reporting, notified cases mostly represent only a proportion of the total number of cases which occurred. This proportion may vary between diseases, between States and Territories and with time. Methods of surveillance vary between jurisdictions, each with different requirements for notification by medical practitioners, laboratories and hospitals. In addition, the list of notifiable diseases and the case definitions may vary between jurisdictions.

Postcode information was well reported but, as it is usually the postcode of residence, it may not necessarily represent the place of acquisition or diagnosis of the disease, or the area in which public health actions were taken in response to the notification. Duplicate checking between the State data sets was not possible, so there may be duplicate reports if patients moved from one jurisdiction to another and were notified in both. Some Statistical Divisions have small populations (Map 1), so small numbers of cases may result in high notification rates in these areas.

The data are limited as they do not include risk factor information other than age, sex, and postcode of residence. Other risk factor information is compiled in data sets supplementary to the NNDSS, for Haemophilus influenzae type b infection,⁸ tuberculosis and non-tuberculosis mycobacterial infection,^9,10 and are reported separately.

National HIV and AIDS surveillance is conducted by the National Centre in HIV Epidemiology and Clinical Research, which reports separately.¹¹ The non-tuberculosis mycobacterial infection notifications are included in the National Mycobacterial Surveillance System which also reports separately.¹⁰

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Results

Some general comments on the numbers of notifications is provided here in this introduction, while data on individual notifiable diseases are described and discussed in disease groups below.

There was a total of 89,579 communicable disease notifications for 1997 (Table 1). Notification rates per 100,000 population for each disease by State or Territory are described in Table 2. Comparative data for 1997 and the preceding four years are shown in Table 3. There was an increase of 37 per cent in total notifications compared with 1996. Forty per cent of the increase is accounted for by the inclusion of hepatitis C (unspecified) data for New South Wales and SA for the first time; 27 per cent of the increase is due to the large number of pertussis notifications.

Many diseases show a fairly constant number of notifications in each year, with tuberculosis being notable in this group. The epidemic of pertussis in the later months of 1997 is reflected in the figures shown here. Notifications of gonococcal infection have increased steadily for several years and hepatitis A and salmonella notifications are higher than seen previously. The number of meningococcal infections notified is higher than in previous years. Notifications of syphilis have fallen steadily over recent years and rubella notifications were low in 1997.

Data were missing from some fields in some records. Information was missing in the field for sex for 847 notifications (0.9%), age for 679 (0.8%), and postcode of residence for 2,441 (2.7%). The proportion of reports with missing data in these fields varied by State or Territory, and also by disease.

Map 1. Australian Bureau of Statistics Statistical Divisions

Statistical Division		Population	Statistical Division		Population	Statistical Division			Population
Australian Capital Territory			Queensland continued			Victoria
805	Canberra	309,462	320	Darling Downs	200,287	205	Melbourne		3,321,666
810	ACT - balance	332	325	South West	26,202	210	Barwon		240,906
New South Wales			330	Fitzroy	179,567	215	Western District		100,125
105	Sydney	3,934,717	335	Central West	12,387	220	Central Highlands		135,443
110	Hunter	561,829	340	Mackay	122,636	225	Wimmera		52,027
115	Illawarra	377,117	345	Northern	193,509	230	Mallee		87,590
120	Richmond-Tweed	203,711	350	Far North	215,518	235	Loddon-Campaspe		158,656
125	Mid-North Coast	265,212	355	North West	35,934	240	Goulburn		184,141
130	Northern	177,196	South Australia			245	Ovens-Murray		89,698
135	North Western	117,407	405	Adelaide	1,083,074	250	East Gippsland		81,002
140	Central West	172,541	410	Outer Adelaide	106,021	255	Gippsland		153,894
145	South Eastern	179,848	415	Yorke and Lower North	44,201	Western Australia
150	Murrumbidgee	149,085	420	Murray Lands	67,520	505	Perth		1,318,974
155	Murray	110,813	425	South East	62,839	510	South West		172,121
160	Far West	24,894	430	Eyre	33,100	515	Lower Great Southern		50,697
Northern Territory			435	Northern	83,051	520	Upper Great Southern		19,729
705	Darwin	84,264	Tasmania			525	Midlands		51,706
710	NT - balance	102,868	605	Greater Hobart	195,468	530	South Eastern		57565
Queensland			610	Southern	34,645	535	Central		59,602
305	Brisbane	1,548,346	615	Northern	133,710	540	Pilbara		41,225
310	Moreton	639,024	620	Mersey-Lyell	109,678	545	Kimberley		26,510
315	Wide Bay-Burnett	227,822				Total Australia		18,529,112

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Table 1. National Notifiable Diseases Surveillance System notifications, 1997, by State or Territory and disease

Disease1	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Total
Arbovirus infection (NEC)	0	0	2	4	0	0	8	4	18
Barmah Forest virus infection	1	190	42	359	4	0	38	70	704
Brucellosis	0	4	0	34	0	0	3	0	41
Campylobacterosis2	261	-	206	4,057	1,939	361	3,612	1,412	11,848
Chancroid	0	0	0	0	0	0	0	1	1
Chlamydial infection (NEC)	142	NN	655	3,447	1,006	263	2,029	1,584	9,126
Cholera	0	2	0	0	0	0	1	0	3
Dengue	1	15	7	168	1	1	3	14	210
Diptheria	0	0	0	0	0	0	0	0	0
Donovanosis	0	NN	31	2	NN	0	0	12	45
Gonococcal infection3	21	633	1,143	906	299	8	386	1,293	4,689
Haemophilus influenzae type b	0	18	4	15	2	2	6	6	53
Hepatitis A	53	1,455	92	894	94	3	363	122	3,076
Hepatitis B - incident	2	50	19	40	16	1	119	0	247
Hepatitis B - unspecified4	113	4,015	1	858	0	31	1,793	303	7,114
Hepatitis C - incident	2	19	1	-	48	2	9	0	81
Hepatitis C - unspecified4	318	8,924	341	2,953	838	236	4,940	1,139	19,689
Hepatitis (NEC)5	0	20	0	3	0	1	5	NN	29
Hydatid infection	0	6	0	12	1	2	31	9	61
Legionellosis	2	38	2	11	39	2	29	38	161
Leprosy	0	1	2	5	1	0	2	3	14
Leptospirosis	0	33	1	56	2	2	27	5	126
Listerosis	0	21	0	9	6	1	15	19	71
Lymphogranuloma venereum	0	0	0	0	0	0	0	0	0
Malaria	17	168	38	374	22	5	90	32	746
Measles	79	260	11	261	29	38	91	83	852
Meningococcal infection	9	221	15	73	22	8	99	52	499
Mumps	7	29	10	14	26	3	66	36	191
Ornithosis	0	NN	0	0	4	0	39	3	46
Pertussis	115	4,094	24	1,785	1,689	119	1,679	1,163	10,668
Q fever	0	275	0	275	8	0	24	11	593
Ross River virus infection	9	1,642	223	2,382	660	14	1,057	696	6,683
Rubella	32	161	7	576	199	17	371	83	1,446
Salmonellosis (NEC)	72	1,706	347	1,835	570	116	1,785	573	7,004
Shigellosis2	5	-	169	207	107	4	79	228	799
Syphilis	8	563	273	309	23	7	20	101	1,304
Tetanus	0	4	0	2	0	1	1	0	8
Tuberculosis	10	446	34	115	54	15	270	64	1,008
Typhoid6	1	28	2	9	3	0	22	12	77
Yersiniosis (NEC)2	2	-	3	181	43	1	15	0	245
Total	1,282	25,044	3,705	22,231	7,755	1,264	19,127	9,171	89,576

NN Not notifiable
NEC Not elsewhere classified.
- Elsewhere classified.
1. No notifications have been received during 1997 for the following rare diseases: botulism (foodborne), plague, rabies, yellow fever, or other viral haemorrhagic fevers.
2. New South Wales: only as 'foodborne disease' or 'gastroenteritis in an institution'.
3. Northern Territory, Queensland, South Australia and Victoria includes gonococcal neonatal ophthalmia.
4. Unspecified numbers should be interpreted with some caution as the magnitude may be the reflection of the numbers of testing being carried out.
5. Includes Hepatitis D and E.
6. Includes paratyphoid in New South Wales and Victoria, and Queensland.

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Table 2. National Notifiable Diseases Surveillance System notification rates per 100,000 population, 1997, by State or Territory and disease

Disease1	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Total
Arbovirus infection (NEC)	0.0	0.0	1.1	0.1	0.0	0.0	0.2	0.2	0.1
Barmah Forest virus infection	0.3	3.0	22.4	10.6	0.3	0.0	0.8	3.9	3.8
Brucellosis	0.0	0.1	0.0	1.0	0.0	0.0	0.1	0.0	0.2
Campylobacterosis2	84.2	-	110.1	119.3	131.0	76.2	78.4	78.5	96.7
Chancroid	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.1	0.0
Chlamydial infection (NEC)	45.8	NN	350.0	101.3	68.0	55.5	44.1	88.1	74.5
Cholera	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Dengue	0.3	0.2	3.7	4.9	0.1	0.2	0.1	0.8	1.1
Diptheria	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Donovanosis	0.0	NN	16.6	0.1	NN	0.0	0.0	0.7	0.4
Gonococcal infection3	6.8	10.1	610.8	26.6	20.2	1.7	8.4	71.9	25.3
Haemophilus influenzae type b	0.0	0.3	2.1	0.4	0.1	0.4	0.1	0.3	0.3
Hepatitis A	17.1	23.2	49.2	26.3	6.4	0.6	7.9	6.8	16.6
Hepatitis B - incident	0.6	0.8	10.2	1.2	1.1	0.2	2.6	0	1.3
Hepatitis B - unspecified4	36.5	64	0.5	25.2	0	6.5	38.9	16.9	38.4
Hepatitis C - incident	0.6	0.3	0.5	-	3.2	0.4	0.2	0.0	0.5
Hepatitis C - unspecified4	102.6	142.2	182.2	86.8	56.6	49.8	107.3	63.3	106.3
Hepatitis (NEC)5	0.0	0.3	0.0	0.1	0.0	0.2	0.1	NN	0.2
Hydatid infection	0.0	0.1	0.0	0.4	0.1	0.4	0.7	0.5	0.3
Legionellosis	0.6	0.6	1.1	0.3	2.6	0.4	0.6	2.1	0.9
Leprosy	0.0	0.0	1.1	0.1	0.1	0.0	0.0	0.2	0.1
Leptospirosis	0.0	0.5	0.5	1.6	0.1	0.4	0.6	0.3	0.7
Listerosis	0.0	0.3	0.0	0.3	0.4	0.2	0.3	1.1	0.4
Lymphogranuloma venereum	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Malaria	5.5	2.7	20.3	11.0	1.5	1.1	2.0	1.8	4.0
Measles	25.5	4.1	5.9	7.7	2.0	8.0	2.0	4.6	4.6
Meningococcal infection	2.9	3.5	8.0	2.1	1.5	1.7	2.1	2.9	2.7
Mumps	2.3	0.5	5.3	0.4	1.8	0.6	1.4	2.0	1.0
Ornithosis	0.0	NN	0.0	NN	0.3	0.0	0.8	0.2	0.4
Pertussis	37.1	65.2	12.8	52.5	114.1	25.1	36.5	64.7	57.6
Q fever	0.0	4.4	0.0	8.1	0.5	0.0	0.5	0.6	3.2
Ross River virus infection	2.9	26.2	119.2	70.0	44.6	3.0	23.0	38.7	36.1
Rubella	10.3	2.6	3.7	16.9	13.4	3.6	8.1	4.6	7.8
Salmonellosis (NEC)	23.2	27.2	185.4	54.0	38.5	24.5	38.8	31.9	37.8
Shigellosis2	1.6	-	90.3	6.1	7.2	0.8	1.7	12.7	6.5
Syphilis	2.6	9.0	145.9	9.1	1.6	1.5	0.4	5.6	7.0
Tetanus	0.0	0.1	0.0	0.1	0.0	0.2	0.0	0.0	0.0
Tuberculosis	3.2	7.1	18.2	3.4	3.6	3.2	5.9	3.6	5.4
Typhoid4	0.3	0.4	1.1	0.3	0.2	0.0	0.5	0.7	0.4
Viral haemorrhagic fever (NEC)	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Yersiniosis (NEC)2	0.6	-	1.6	5.3	2.9	0.2	0.3	0.0	2.0

NN Not notifiable
NEC Not elsewhere classified.
- Elsewhere classified.
1. No notifications have been received during 1997 for the following rare diseases: botulism (foodborne), plague, rabies, yellow fever, or other viral haemorrhagic fevers.
2. New South Wales: only as 'foodborne disease' or 'gastroenteritis in an institution'.
3. Northern Territory, Queensland, South Australia and Victoria includes gonococcal neonatal ophthalmia.
4. Unspecified numbers should be interpreted with some caution as the magnitude may be the reflection of the numbers of testing being carried out.
5. Includes Hepatitis D and E.
6. Includes paratyphoid in New South Wales and Victoria, and Queensland.

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Table 3. National Notifiable Diseases Surveillance System notifications and rates, 1993 to 1997, by year¹ and disease

Disease1,2	Notifications					Rate per 100,000 population
	1993	1994	1995	1996	1997	1993	1994	1995	1996	1997
Arbovirus infection (NEC)	578	587	67	52	18	3.3	3.3	0.4	0.3	0.1
Barmah Forest virus infection	-	-	756	837	704	-	-	4.7	4.6	3.8
Brucellosis	20	34	29	38	41	0.1	0.2	0.2	0.2	0.2
Campylobacteriosis	8,111	10,117	10,933	12,158	11,848	69.6	85.8	91.6	100.4	96.7
Chancroid	1	0	2	3	1	0.0	0.0	0.0	0.0	0.0
Chlamydial infection (NEC)	6,500	6,159	6,411	8,420	9,126	55.8	55.3	53.7	69.6	74.5
Cholera	6	3	5	4	3	0.0	0.0	0.0	0.0	0.0
Dengue	690	17	34	43	210	4.5	0.1	0.2	0.2	1.1
Diphtheria	1	0	0	0	0	0.0	0.0	0.0	0.0	0.0
Donovanosis	67	117	85	50	45	0.7	1.1	0.8	0.5	0.4
Gonococcal infection	2,811	2,971	3,259	4,173	4,689	15.9	16.7	18.1	22.8	25.3
Haemophilus influenzae type b	396	169	74	51	53	2.2	1.0	0.4	0.3	0.3
Hepatitis A	2,006	1,894	1,601	2,150	3,076	11.4	10.6	8.9	11.7	16.6
Hepatitis B - incident	278	327	321	225	247	2.2	1.9	1.8	1.2	1.3
Hepatitis B - unspecified	NPR	NPR	NPR	NPR	7,114	NPR	NPR	NPR	NPR	38.4
Hepatitis C - incident	30	43	69	72	81	0.4	0.6	0.8	0.8	0.5
Hepatitis C - unspecified3	7,542	8,898	9,601	9,489	19,689	73.9	86.2	91.8	89.3	106.3
Hepatitis (NEC)	72	42	55	36	29	0.5	0.3	0.3	0.2	0.2
Hydatid infection	32	56	46	45	61	0.2	0.3	0.3	0.2	0.3
Legionellosis	178	179	160	192	161	1.0	1.0	0.9	1.0	0.9
Leprosy	15	11	7	10	14	0.1	0.1	0.0	0.1	0.1
Leptospirosis	178	123	148	227	126	1.0	0.7	0.8	1.2	0.7
Listeriosis	53	34	58	70	71	0.3	0.2	0.3	0.4	0.4
Lymphogranuloma venereum	1	2	1	0	0	0.0	0.0	0.0	0.0	0.0
Malaria	688	703	625	849	746	3.9	3.9	3.5	4.6	4.0
Measles	4,536	4,895	1,324	498	852	25.7	27.4	7.3	2.7	4.6
Meningococcal infection	378	383	382	426	499	2.1	2.2	2.1	2.3	2.7
Mumps	28	94	153	128	191	0.2	0.5	1.0	0.9	1.0
Ornithosis	98	85	176	85	46	0.8	0.7	1.5	0.7	0.4
Pertussis	3,990	5,633	4,297	4,031	10,668	22.6	31.6	23.8	22.0	57.6
Q fever	889	667	473	555	593	5.0	3.7	2.6	3.0	3.2
Ross River virus infection	5,428	3,974	2,602	7,823	6,683	31.6	22.9	14.4	42.7	36.1
Rubella	3,812	3,315	4,380	2,845	1,446	21.6	18.6	24.3	15.5	7.8
Salmonellosis (NEC)	4,731	5,283	5,895	5,819	7,004	26.8	29.6	32.7	31.8	37.8
Shigellosis	708	724	734	676	799	6.1	6.1	6.1	5.6	6.5
Syphilis	2,305	2,324	1,854	1,523	1,304	13.1	13.0	10.3	8.3	7.0
Tetanus	10	15	7	2	8	0.1	0.1	0.0	0.0	0.0
Tuberculosis	1,071	1,024	1,073	1,067	1,008	6.1	5.7	5.9	5.8	5.4
Typhoid4	72	50	69	84	77	0.4	0.3	0.4	0.5	0.4
Yersiniosis (NEC)	459	414	306	268	245	3.9	3.5	2.6	2.2	2.0
Total	60,745	61,726	58,074	65,382	89,576

NEC Not Elsewhere Classified.
NN Not notifiable.
- Elsewhere classified.
1. No notifications have been received during 1993 to 1997 for the following rare diseases: botulism (foodborne), plague, rabies, yellow fever, or other viral haemorrhagic fevers.
2. Not all diseases were notifiable in every State and Territory every year.
3. Data from SA and NSW included for the first time in 1997.
4. Includes paratyphoid in New South Wales and Victoria, and from July 1996 in Queensland
NPR Not previously reported.

Author affiliations

1. National Centre for Disease Control, Department of Health and Aged Care, for the Communicable Diseases Network Australia New Zealand

2. National Centre for Epidemiology and Population Health

3. National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases

This article {extract} was published in Communicable Diseases Intelligence Vol 23 Number , 21 January 1999 and may be downloaded as a full version PDF from the Table of contents page. Volume 23 1999.