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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.

Rates of influenza-like illness reported by the General Practitioner Surveillance Schemes for 1998 have been lower than reports over the same period in 1997. This is in contrast with the laboratory surveillance data that shows higher than normal reports of influenza A compared to all previous years dating back to 1993.

Sentinel General Practitioner Surveillance

Consultation rates for influenza-like illness recorded by the ASPREN scheme showed a decline in the month of July but this trend did not continue for the first two weeks of August (Figure 1), and rates are still around 20 per 1,000 consultations. The New South Wales Sentinel Scheme reported the highest rates of 42.9 per 1,000 in early August and the winter peak of influenza activity is still not over. Reported consultation rates for influenza-like illness across all schemes were less than the 50 per 1,000 consultations reported in late July and early August of last year. The Tropical Influenza Surveillance Programme has reported weekly consultation rates that have been consistently less than 13 per 1,000 for the year to the end of July. 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.

Laboratory Surveillance

There have been 1,559 laboratory reports of influenza for the year to date. Of these, 1,461 (91%) were influenza A and 98 (9 %) influenza B (Figure 2). 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. As the rates of clinical disease have not risen, the laboratory figures are likely to reflect an increase in rates of laboratory testing, rather than a true increase in influenza A. Of laboratory reports of influenza A, a total of 420 (29%) were in children less than 4 years of age. By contrast, children less than 4 years of age accounted for only 3% of reports of all influenza B laboratory reports (Figure 3).

WHO Collaborating Centre for Influenza Reference and Research

To date this season, 448 influenza isolates from Australian laboratories have been analysed. All of these viruses are influenza A (H3N2) subtype strains, no influenza A (H1N1) isolates have been reported and no viable influenza B isolates have been received.

The isolates, which are all cell-culture grown viruses, are antigenically related to the vaccine strain A/Sydney/5/97. However, approximately 30% of the viruses demonstrate some reduction in reactivity with A/Sydney/5/97 antiserum. Further analysis of these less reactive strains is continuing.
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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 been no greater than 0.29% (Figure 4).

Figure 1. Sentinel general practitioner consultation rates, 1998, by week and scheme



Figure 2. Influenza laboratory reports, 1998, by virus type and week of specimen collection



Figure 3. Influenza laboratory reports, 1998, by virus type and age group



Figure 4. Australia Post absenteeism rates, May to September 1998, by week


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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.

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 March 1 to March 31 1998, as reported to 30 June 1998, are included in this issue of CDI (Tables 6 and 7).

Table 6. New diagnoses of HIV infection, new diagnoses of AIDS and deaths following AIDS occurring in the period 1 to 31 March 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	6	0	2	0	0	1	1	10	9	18	23
	Male	0	33	0	8	4	2	10	3	60	53	177	197
	Sex not reported	0	1	0	0	0	0	0	0	1	2	4	7
	Total1	0	40	0	10	4	2	11	4	71	64	199	227
AIDS diagnoses	Female	0	0	0	1	0	0	0	0	1	5	2	9
	Male	0	1	1	3	1	0	1	0	7	20	31	88
	Total1	0	1	1	4	1	0	1	0	8	25	33	97
AIDS deaths	Female	0	0	0	0	0	0	1	1	2	0	2	4
	Male	0	1	0	1	0	0	3	0	5	23	20	76
	Total1	0	1	0	1	0	0	4	1	7	23	22	80

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 31 March 1998, by sex and State or Territory

		ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Australia
HIV diagnoses	Female	20	546	7	123	52	4	193	86	1,031
	Male	180	10,262	93	1,790	627	77	3,710	850	17,589
	Sex not reported	0	260	0	0	0	0	28	0	288
	Total1	200	11,088	100	1,919	679	81	3,941	939	18,947
AIDS diagnoses	Female	7	157	0	45	19	2	64	23	317
	Male	80	4,333	31	759	320	41	1,526	337	7,427
	Total1	87	4,501	31	806	339	43	1,597	362	7,766
AIDS deaths	Female	2	112	0	28	14	2	45	16	219
	Male	62	3,040	23	527	216	27	1,204	241	5,340
	Total1	64	3,159	23	557	230	29	1,255	258	5,575

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

This article was published in Communicable Diseases Intelligence Volume 22, No 9, 3 September 1998.