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National Influenza Surveillance, 1998

Three types of data are included in National Influenza Surveillance, 1998. These are sentinel general practitioner surveillance conducted by the Australian Sentinel Practice Research Network, Department of Human Services (Victoria), Department of Health (New South Wales) and the Tropical Influenza Surveillance Scheme, Territory Health (Northern Territory); laboratory surveillance data from the Communicable Diseases Intelligence Virology and Serology Laboratory Reporting Scheme, LabVISE, and the World Health Organization Collaborating Centre for Influenza Reference and Research; and absenteeism surveillance conducted by Australia Post. For further information about these schemes, see Commun Dis Intell 1998;22:83.

Sentinel General Practitioner Surveillance

Consultation rates for influenza-like illness recorded by ASPREN have peaked at 21.3 per 1,000 for the month of July (Figure 5). This figure is less than that reported for the same time last year, when the seasonal peak reached 50 per 1,000 consultations. The New South Wales and Victorian Sentinel Schemes have reported rates of 32.7 and 26.4 per 1,000 respectively for this reporting period. The Tropical Influenza Surveillance Programme has reported weekly consultation rates that have been consistently less than 10 per 1,000 for the year to date. This contrasts with 1997, when there was an early peak of 30 per 1,000 consultations in the month of March and a late winter peak that reached the same levels.

Figure 5. Sentinel general practitioner consultation rates, 1998, by week and scheme.

Laboratory Surveillance

There have been 1,073 laboratory reports of influenza for the year to date. Of these, 991 (92%) were influenza A and 82 (8 %) influenza B (Figure 6). The number of influenza A reports for this year is greater than those reported over the same period for all years dating back to 1993. This however contrasts with the sentinel general practitioner data schemes that are reporting rates of influenza-like illness that are comparable to those of last year, and which for the most recent reporting period are lower than those reported for 1997. A total of 219 laboratory reports of influenza A were in children less than 4 years of age (Figure 7). Again this is in contrast to the data provided by the ASPREN scheme that reports the largest number of influenza-like illness in the 15 to 44 year old age group (Figure 8).

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Figure 6. Influenza laboratory reports, 1998, by virus type and week of specimen collection

Figure 7. Influenza A and B laboratory reports, 1998, by age group

Figure 8. Reports of influenza-like illness, ASPREN Scheme, 1998, by age group

Absenteeism surveillance

Rates of absenteeism in Australia Post employees for three consecutive days of each week have been reported on a weekly basis since late April. Absenteeism rates for the year have averaged 0.26% per week. Rates for this reporting period have peaked at 0.32% for the first week of July which is the highest reported for the year so far.

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Sentinel Chicken Surveillance Programme

Sentinel chicken flocks are used to monitor flavivirus activity in Australia. The main viruses of concern are Murray Valley encephalitis (MVE) and Kunjin which cause the potentially fatal disease Australian encephalitis in humans. Currently 26 flocks are maintained in the north of Western Australia, seven in the Northern Territory, nine in New South Wales and ten in Victoria. The flocks in Western Australia and the Northern Territory are tested year round but those in New South Wales and Victoria are tested only from November to March, during the main risk season.

Results are coordinated by the Arbovirus Laboratory in Perth and reported bimonthly. For more information see Commun Dis Intell 1998;22:7

AK Broom¹, JS Mackenzie,² L Melville³, DW Smith⁴ and PI Whelan⁵

1. Department of Microbiology, The University of Western Australia
2. Department of Microbiology, The University of Queensland
3. Berrimah Agricultural Research Centre, Northern Territory
4. PathCentre, Western Australia
5. Department of Health and Community Services, Northern Territory

Sentinel chicken serology was carried out for 21 of the 28 flocks in Western Australia in June 1998. There were three seroconversions in the Fitzroy Crossing flock to Kunjin virus and six seroconversions in the Derby flocks. There was one seroconversion to Kunjin virus at Derby site 2 (town) and five seroconversions at Derby site 1 (located out of town), three to Kunjin virus and two to a flavivirus that does not appear to be MVE or Kunjin virus. This increase in Kunjin virus activity in the West Kimberley region is unusual at this time of year, particularly after a wet season with below average rainfall and low flavivirus activity.

Seven flocks of sentinel chickens from the Northern Territory were also tested in our laboratory in June 1998. There was one seroconversion to Kunjin virus in the Leanyer flock and one seroconversion to a flavivirus only in the Gove flock. The chicken from Tennant Creek that seroconverted in April 1998 was confirmed as a Kunjin seroconversion.

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HIV and AIDS Surveillance

National surveillance for HIV disease is coordinated by the National Centre in HIV Epidemiology and Clinical Research (NCHECR), in collaboration with State and Territory health authorities and the Commonwealth of Australia. Cases of HIV infection are notified to the National HIV Database on the first occasion of diagnosis in Australia, by either the diagnosing laboratory (ACT, New South Wales, Tasmania, Victoria) or by a combination of laboratory and doctor sources (Northern Territory, Queensland, South Australia, Western Australia). Cases of AIDS are notified through the State and Territory health authorities to the National AIDS Registry. Diagnoses of both HIV infection and AIDS are notified with the person's date of birth and name code, to minimise duplicate notifications while maintaining confidentiality.

Table 6. New diagnoses of HIV infection, new diagnoses of AIDS and deaths following AIDS occurring in the period 1 to 28 February 1998, by sex and State or Territory of diagnosis

		State or territory								Totals for Australia
		ACT	NSW	NT	Qld	SA	Tas	Vic	WA	This period 1998	This period 1997	Year to date 1998	Year to date 1997
HIV diagnoses	Female	0	1	0	0	1	0	1	1	4	3	5	14
	Male	2	23	0	0	3	0	18	1	47	66	105	144
	Sex not reported	0	2	0	0	0	0	0	0	2	4	3	5
	Total1	2	226	0	0	4	0	19	2	53	73	113	163
AIDS diagnoses	Female	0	0	0	0	0	0	0	0	0	2	1	4
	Male	0	2	0	3	0	0	1	1	7	28	16	68
	Total1	0	2	0	3	0	0	1	1	7	30	17	72
AIDS deaths	Female	0	0	0	0	0	0	0	0	0	2	0	4
	Male	0	1	0	1	0	0	0	0	2	25	8	53
	Total1	0	1	0	1	0	0	0	0	2	27	8	57

1. Persons whose sex was reported as transgender are included in the totals.

Table 7. Cumulative diagnoses of HIV infection, AIDS and deaths following AIDS since the introduction of HIV antibody testing to 28 February 1998, by sex and State or Territory

		ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Australia
HIV diagnoses	Female	20	539	7	120	52	4	192	83	1,017
	Male	180	10,229	93	1,772	622	75	3,700	841	17,514
	Sex not reported	0	260	0	0	0	0	28	1	289
	Total1	200	11,048	100	1,898	676	79	3,930	928	18,859
AIDS diagnoses	Female	7	157	0	44	19	2	62	23	314
	Male	80	4,332	30	756	318	41	1,517	337	7,411
	Total1	87	4,500	30	802	337	43	1,586	362	7,747
AIDS deaths	Female	2	112	0	28	14	2	43	15	216
	Male	52	3,035	23	525	215	27	1,198	241	5,316
	Total1	54	3,154	23	555	229	29	1,247	257	5,548

1. Persons whose sex was reported as transgender are included in the totals.

Tabulations of diagnoses of HIV infection and AIDS are based on data available three months after the end of the reporting interval indicated, to allow for reporting delay and to incorporate newly available information. More detailed information on diagnoses of HIV infection and AIDS is published in the quarterly Australian HIV Surveillance Report, available from the National Centre in HIV Epidemiology and Clinical Research, 376 Victoria Street, Darlinghurst NSW 2010. Telephone: (02) 9332 4648 Facsimile: (02) 9332 1837.

HIV and AIDS diagnoses and deaths following AIDS reported for 1 to 28 February 1998, as reported to 31 May 1998, are included in this issue of CDI (Tables 6 and 7).

The cumulative Australian totals for HIV diagnoses over recent months has not appeared to follow the expected trend due to changes in the reporting methods. The changes to the HIV reporting system are presented on page 161.

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Childhood immunisation coverage

Table 8 provides the latest quarterly report on childhood immunisation coverage from the Australian Childhood Immunisation Register (ACIR).

The data show the percentage of children fully immunised at age 12 months for the cohort born between 1 October and 31 December 1996 according to the Australian Standard Vaccination Schedule.

A full description of the methodology used can be found in Commun Dis Intell 1998;22:3;36-37.

Table 8. Percentage of children immunised at 1 year of age, preliminary results by disease and State for the birth cohort 1 October 1996 to 31 December 1996; assessment date 31 December 1997

	State or Territory								Australia
	ACT	NSW	NT	Qld	SA	Tas	Vic	WA
Total number of children	1,086	22,119	837	11,598	4,650	1,652	15,991	6,200	64,133
Vaccine
DTP (%)	85.8	78.4	67.0	84.3	80.5	82.9	83.1	76.7	80.7
OPV (%)	85.4	78.1	66.8	84.6	80.6	83.3	83.1	76.9	80.7
Hib (%)	82.4	77.9	70.8	85.1	80.6	82.9	82.9	76.9	80.7
Fully Immunised (%)	81.9	75.7	61.6	82.5	78.6	81.7	81.5	75.1	78.6
Change in fully immunised since last quarter (%)	+1.3	+1.0	+6.6	+3.1	-0.3	+2.5	+1.6	+4.6	+1.9

Acknowledgement: These figures were provided by the Health Insurance Commission (HIC), to specifications provided by the Commonwealth Department of Health and Family Services. For further information on these figures or data on the ACIR please contact the Immunisation Section of the HIC: Telephone (02) 6203 6185.

This article was published in Communicable Diseases Intelligence Vol 22 No 8, 6 August 1998.