Australian influenza report 2010 - 28 August to 3 September 2010 (#35/10)

The Australian Influenza Report is compiled from a number of data sources, including laboratory-confirmed notifications to NNDSS, sentinel influenza-like illness reporting from general practitioners and emergency departments, workplace absenteeism, and laboratory testing. A more in-depth annual report is also published in Communicable Diseases Intelligence.

Page last updated: 13 September 2010

Report No. 35
Week ending 3 Septmeber 2010

A print friendly version of this report is available as a PDF (292 KB)

The Department of Health and Ageing acknowledges the providers of the many sources of data used in this report and greatly appreciates their contribution.

Key Indicators

Influenza activity and severity in the community is monitored using the following indicators and surveillance systems:

Is the situation changing?

Indicated by trends in:

  • laboratory confirmed cases reported to the National Notifiable Diseases Surveillance System;
  • GP Sentinel influenza-like illness (ILI) Surveillance;
  • emergency department (ED) presentations for ILI;
  • ILI-related absenteeism and call centre calls: and
  • sentinel laboratory test results.

How severe is the disease, and is severity changing?

Indicated by trends in:

  • hospitalisations, ICU admissions and deaths from sentinel systems; and
  • clinical severity in hospitalised cases and ICU admissions.

Is the virus changing?

Indicated by trends in:

  • drug resistance; and
  • genetic drift or shift from laboratory surveillance.

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Summary

  • Levels of influenza and influenza-like illness (ILI) in the community have continued to increase through all surveillance systems this reporting period and highlight a late start to the influenza season compared to previous years.
  • There were 501 laboratory confirmed notifications of influenza during this reporting period, including 361 pandemic (H1N1) 2009 cases. Notifications of laboratory confirmed influenza were highest in SA and QLD.
  • Results from sentinel laboratory surveillance systems for this reporting period show that 19% of the respiratory tests conducted over this period were positive for influenza, which is similar to the last reporting period (17%). In 2010, a total of 694 specimens have been positive for influenza (of 10,554 specimens tested), of which 70% were pandemic (H1N1) 2009 and 12% were A/H3N2.
  • Of the 4,152 confirmed cases of influenza diagnosed during 2010 up to 3 September, 1,935 (47%) have been sub-typed as pandemic (H1N1) 2009. A total of 39,571 confirmed cases of pandemic (H1N1) 2009 have occurred in Australia since May 2009.
  • Sentinel hospitals have reported 16 hospitalisations for influenza during the reporting period, including 13 for pandemic (H1N1) 2009. ANZICS reported two ICU admissions for influenza and the APSU has reported nine cases of influenza complications in children aged less than 15 years this reporting period.
  • The WHO has advised that the world is no longer in phase 6 of influenza pandemic alert, and will now move into the post pandemic period. As at 1 August 2010, over 18,449 deaths worldwide have been reported associated with the pandemic virus. The WHO is currently reporting that transmission remains locally intense in parts of India and in parts of the temperate southern hemisphere, particularly New Zealand and more recently Australia.
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    1. Influenza activity in Australia

    Geographic spread of influenza and ILI – Jurisdictional Surveillance

    In the fortnight ending 3 September, influenza and ILI activity as reported by state and territory Health Departments indicated that there was ‘sporadic’ activity in TAS, ‘local’ activity in the ACT, ‘regional’ activity in NT, QLD and NSW and ‘widespread’ activity in SA, WA and Vic (Figure 1). Definitions of these activity levels are provided in the Data Considerations section of this report.

    Figure 1. Map of influenza and ILI activity, by state and territory, during fortnight ending 3 September 2010

    Figure 1. Map of influenza and ILI activity, by state and territory, during fortnight ending 3 September 2010

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    Influenza-Like Illness

    Sentinel General Practice Surveillance

    In the week ending 29 August 2010,the national ILI consultation rate to sentinel GPs was approximately 14 cases per 1,000 consultations (Figure 2), an increase from the previous week. Although the rate in 2010 has had a slight upward trend since the beginning of the year, the consultation rate remains below the rate experienced at this time in previous years.

    Figure 2. Weekly rate of ILI reported from GP ILI surveillance systems from 1 January 2007 to 29 August 2010*

    Figure 2. Weekly rate of ILI reported from GP ILI surveillance systems from 1 January 2007 to 29 August 2010

    * Delays in the reporting of data may cause data to change retrospectively. As data from the VIDRL surveillance system is combined with ASPREN data for 2010, rates may not be directly comparable across 2007, 2008 and 2009.



    SOURCE: ASPREN, and VIDRL GP surveillance system.


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    WA Emergency Departments

    Respiratory viral presentations reported in Western Australian EDs have continued to increase in recent weeks, and an overall upward trend has been observed since the beginning of 2010 (Figure 3). In the week ending 29 August 2010 there were 561 respiratory viral presentations, including 33 admissions, an increase from 496 presentations in the previous reporting week.

    Figure 3. Number of respiratory viral presentations to Western Australia EDs from 1 January 2007 to 29 August 2010 by week

    Figure 3. Number of respiratory viral presentations to Western Australia EDs from 1 January 2007 to 29 August 2010 by week

    Source: WA ‘Virus Watch’ Report


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    NSW Emergency Departments

    In the week ending 20 August 2010, ILI presentations to NSW EDs remained low and stable (Figure 4). In August 2010, there were 236 presentations with influenza-like illness, a rate of 1.7 per 1,000 presentations, with 19 admissions to hospital following presentation to emergency departments with ILI. This is similar to the previous month and the count of presentations is significantly lower that in August 2009, but similar to the same periods in 2005-2008.

    Figure 4: ILI presentations to NSW EDs from 2007-2010, by week

    Figure 4: ILI presentations to NSW EDs from 2007-2010, by week

    Source: NSW Health ‘Influenza Weekly Epidemiology Report


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    Flutracking

    Flutracking, a national online system for collecting data on ILI in the community, reported that in the week ending 5 September 2010, ILI levels continued at low levels (Figure 5), with fever and cough reported at a slightly higher rate amongst unvaccinated participants (3.6% compared to 3.4% in vaccinated participants).

    Figure 5. Rate of ILI symptoms among Flutracking participants by week, from week ending 30 May 2010 to week ending 5 September 2010

    Figure 5. Rate of ILI symptoms among Flutracking participants by week, from week ending 30 May 2010 to week ending 5 September 2010

    Source: Flutracking Interim Weekly Report


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    National Health Call Centre Network

    The number of calls to the National Health Call Centre Network (NHCCN) in this reporting period was similar to previous reporting periods (Figure 6).

    Although ILI-related calls have been increasing gradually since the start of 2010, the number of ILI calls and percent of total calls are only slightly above levels seen in late 2009. Call numbers cannot be compared between early 2009 and early 2010 as not all call centres were online in early 2009. The difference in operating call centre numbers accounts for this apparent increase in recorded ILI calls (and baseline levels) between the two years.

    Figure 6. Number of calls to the NHCCN related to ILI and percentage of total calls, Australia, 1 January 2009 to 3 September 2010

    Figure 6. Number of calls to the NHCCN related to ILI and percentage of total calls, Australia, 1 January 2009 to 3 September 2010

    Note: national data does not include QLD and VIC
    Source: NHCCN data


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    Absenteeism

    In the week ending 14 July 2010, absenteeism increased to 1.1% (Figure 7). Overall there has been a gradual increasing trend since the beginning of 2010. Please note, due to system changes, this data has not been updated for six weeks.

    Figure 7. Rates of absenteeism (greater than 3 days absent on sick leave), national employer, from 28 January 2007 to 14 July 2010, by week

    Figure 7. Rates of absenteeism (greater than 3 days absent on sick leave), national employer, from 28 January 2007 to 14 July 2010, by week

    SOURCE: Absenteeism data


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    Laboratory confirmed influenza

    Sentinel Laboratory Surveillance

    Results from sentinel laboratory surveillance systems for this reporting period show that 19% (143/716) of the respiratory tests conducted over this period were positive for influenza, which is an increase on the last reporting period (17%) (Figure 8).

    Figure 8. Total number of specimens tested by sentinel laboratories, and proportion positive, 1 January 2010 to 3 September 2010, by week

    Figure 8. Total number of specimens tested by sentinel laboratories, and proportion positive, 1 January 2010 to 3 September 2010, by week

    SOURCE: Sentinel laboratory data from ASPREN, NSW NIC, WA NIC, VIC NIC & TAS Labs



    Sentinel laboratories reported 143 specimens positive for influenza during this reporting period, of which 110 were pandemic (H1N1) 2009, 4 were A/H3N2, 6 were influenza A untyped and 23 were influenza B (Table 1).
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    Table 1. Laboratory respiratory tests that tested positive for influenza

    2009# 2010a
      Confirmed pandemic
    (H1N1) 2009 cases
    Hospitalised cases ICU cases Deaths Confirmed (H1N1) 2010 cases Deaths
    Total number
    37,636
    13% (4,992/37,636) confirmed cases)
    14%
    (681/4,992 hospitalisations)
    191
    1935
    7b
    Crude rate per 100,000 population
    172.1
    22.8
    3.1
    0.9
    8.9
    n/a
    Median age (years)
    21
    31
    44
    53
    24
    53
    Females
    51% (19,139/37,636)
    51% (2,528/4,992)
    53%
    (364/681)
    44%
    50.3%
    (974/1935)
    43%
    (3/7)
    Vulnerable groups (Indigenous persons, pregnant women & individuals with at least 1 co-morbidity)
    n/a
    58% (2,892/4,992)
    74%
    (504/681)
    67%
    n/a
    n/a
    Indigenous people~
    11% (3,877/34,750)
    20%
    (808/4,048)
    19%
    (102/533)
    13%
    5.5%
    (48/871)
    n/a
    Pregnant women*
    n/a
    27%
    (287/1,056 hospitalised females aged
    15-44 years)
    16%
    (47/289) hospitalised pregnant women)
    4%
    n/a
    n/a
    Cases with at least 1 co-morbidity
    n/a
    46% (2,303/4,992)
    67%
    (457/681)
    62%
    n/a
    n/a


    In 2010, a total of 694 specimens have been positive for influenza (7% of 10,554 specimens tested), of which 70% were pandemic (H1N1) 2009 and 12% were A/H3N2 (Figure 9). Sentinel laboratory data are used in addition to National Notifiable Diseases Surveillance System (NNDSS) data to understand the strains circulating in Australia, as approximately 43% of NNDSS notifications are reported as influenza A untyped.

    Figure 9. Percentage of specimens tested by sentinel laboratories influenza positive, 1 January 2010 to 3 September 2010, by subtype

    Figure 9. Percentage of specimens tested by sentinel laboratories influenza positive, 1 January 2010 to 3 September 2010, by subtype

    SOURCE: Sentinel laboratory data from ASPREN, NSW NIC, WA NIC, VIC NIC & TAS Labs


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    Laboratory Confirmed Cases Notified to Health Departments

    During this reporting period, 501 confirmed cases of influenza were notified (241 in SA, 147 in QLD, 60 in WA, 20 in VIC, 19 in NSW, 8 in the NT, 4 in the ACT, and 2 in TAS). They included 361 cases of pandemic (H1N1) 2009, 96 of influenza A (untyped), 1 case of influenza A/H3N2, 23 of influenza B, and 17 untyped.

    There have been 4,152 confirmed cases of influenza of all types diagnosed during 2010 up to 3 September (Figure 10). Of these, 1,935 (47%) have been sub-typed as pandemic (H1N1) 2009, 1,800 (43%) as influenza type A untyped, 81 (2%) as A/H3N2 and 11 (<1%) as type A&B. A further 269 (6%) have been characterised as influenza type B, 55 (1%) were untyped, and one was sub-typed as seasonal A/H1N1 in a traveller who had returned from Ireland.

    Figure 10. Laboratory confirmed cases of influenza in Australia, 1 January 2005 to 3 September 2010

    Figure 10. Laboratory confirmed cases of influenza in Australia, 1 January 2005 to 3 September 2010

    Source: NetEpi (2009; NSW 2010) and NNDSS (2010)
    Note: The scale in this figure has been limited to 1600 notifications per week to allow for comparison
    between 2010 and previous years. In 2009, notifications peaked at approximately 8,300 in Week 30.


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    In 2010 up to 3 September, the number of laboratory confirmed cases of influenza was 1,227 in QLD, 606 in NSW, 776 in VIC, 578 in WA and 799 in SA. There were a further 76 cases in the NT, 53 in the ACT and 37 cases in TAS (Figure 11).

    Figure 11. Laboratory confirmed cases of influenza in Australia, 1 January to 3 September 2010, by state, by week.


    Figure 11. Laboratory confirmed cases of influenza in Australia, 1 January to 3 September 2010, by state, by week

    In 2010, the distribution of influenza notifications is relatively consistent across all age groups with an overall slight downward trend with increasing age. This distribution is reasonably similar to 2008 except in the 0-4 and the 74 and over age groups where sharp increases are seen (Figure 12). In 2009 the distribution of influenza notifications tended to occur in persons aged less than 55 years, with substantially higher rates observed in persons aged less than 30 years, compared to older age groups.
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    Figure 12. Laboratory confirmed cases of influenza (pandemic (H1N1) 2009 and seasonal) in Australia, 1 January 2008 to 3 September 2010, by age group

    Figure 12. Laboratory confirmed cases of influenza (pandemic (H1N1) 2009 and seasonal) in Australia, 1 January 2008 to 3 September 2010, by age group

    Source: NNDSS and NetEpi (NSW).



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    2. Influenza severity to 3 September 2010*

    Pandemic (H1N1) 2009

    While pandemic (H1N1) 2009 is generally considered a mild disease at the community level, it has had serious consequences for some who experience it. Figures of hospitalisations, ICU admissions and deaths are currently used as indicators of the severity of the disease in Australia (Table 2).

    Pandemic (H1N1) data for 2009 are currently being finalised through cleaning and validation processes. It is possible that these processes will result in some changes in the data presented here. Validated data will be progressively reported as these steps are completed.

    Since the first case of pandemic (H1N1) 2009 in Australia in May 2009, there have been a total of 39,571 confirmed cases of pandemic (H1N1) 2009 in Australia as at 3 September 2010. Of these, 37,636 cases were reported in 2009 and 1,935 cases were reported in 2010. A total of 198 pandemic influenza-associated deaths have been reported, with 7 deaths occurring in 2010.

    * Note that while the analysis of severity is on-going, updates are presented as required when there are significant changes detected. With the current low levels of pandemic (H1N1) 2009 influenza activity in Australia it is anticipated that the indicators of pandemic associated severity will not vary significantly.



    Table 2. Summary of severity indicators of pandemic (H1N1) in Australia, 2009 and 2010 (up to 3 September 2010)

    2009# 2010a
      Confirmed pandemic
    (H1N1) 2009 cases
    Hospitalised cases ICU cases Deaths Confirmed (H1N1) 2010 cases Deaths
    Total number
    37,636
    13% (4,992/37,636) confirmed cases)
    14%
    (681/4,992 hospitalisations)
    191
    1935
    7b
    Crude rate per 100,000 population
    172.1
    22.8
    3.1
    0.9
    8.9
    n/a
    Median age (years)
    21
    31
    44
    53
    24
    53
    Females
    51% (19,139/37,636)
    51% (2,528/4,992)
    53%
    (364/681)
    44%
    50.3%
    (974/1935)
    43%
    (3/7)
    Vulnerable groups (Indigenous persons, pregnant women & individuals with at least 1 co-morbidity)
    n/a
    58% (2,892/4,992)
    74%
    (504/681)
    67%
    n/a
    n/a
    Indigenous people~
    11% (3,877/34,750)
    20%
    (808/4,048)
    19%
    (102/533)
    13%
    5.5%
    (48/871)
    n/a
    Pregnant women*
    n/a
    27%
    (287/1,056 hospitalised females aged
    15-44 years)
    16%
    (47/289) hospitalised pregnant women)
    4%
    n/a
    n/a
    Cases with at least 1 co-morbidity
    n/a
    46% (2,303/4,992)
    67%
    (457/681)
    62%
    n/a
    n/a


    #Data are extracted from a number of sources depending on the availability of information. Figures used in the analysis have been provided in parentheses. Data are not always complete for each summarised figure.
    a Data for 2009 from NetEpi, data for 2010 from NNDSS and NetEpi (NSW).
    bThe number of deaths is most likely under-reported and representative of hospital related death notifications only.n/a - No data collected or available.
    ~The denominator for this row is the number of confirmed cases for which Indigenous status is known. In 2010, 1064 cases had Indigenous status unknown.
    *Includes women in the post-partum period.


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    Influenza Hospitalisations

    Influenza Complications Alert Network (FluCAN)

    The Influenza Complications Alert Network (FluCAN) reported 13 pandemic (H1N1) 2009 hospitalisations, one influenza A (not subtyped) hospitalisation and two influenza B hospitalisations from sentinel hospitals in the week ending 3 September 2010. For the period of 1 March to 3 September 2010, FluCAN has reported a total of 118 influenza associated hospitalisations (Figure 12). Of these hospitalisations, 91 have been associated with pandemic (H1N1) 2009, including 27 with ICU admission.

    Figure 13. Number of influenza hospitalisations, sentinel hospitals, Australia, 1 March to 3 September 2010

    Figure 13. Number of influenza hospitalisations, sentinel hospitals, Australia, 1 March to 3 September 2010

    Source: Influenza Complications Alert Network (FluCAN). Data from 14 sentinel hospitals from all jurisdictions.


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    Australian Paediatric Surveillance Unit (APSU)


    A survey of admissions of children aged 15 years and under to Intensive Care Units (ICUs) around Australia following complications due to influenza infection is conducted through the Australian Paediatric Surveillance Unit (APSU). Details of admissions are reported on a weekly basis.

    For the week ending 6 September 2010, there were nine cases of severe influenza complications in children. Since 1 July 2010, 14 cases of hospitalisations related to severe influenza complications have been reported in children aged 15 years and under. Eight cases have been associated with pandemic (H1N1) 2009, of which two were admitted to ICU. Two cases were associated with Influenza A (not further subtyped), and one case was associated with influenza B. Two of the cases associated with pandemic (H1N1) 2009 had an underlying chronic condition.
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    Intensive care admissions


    The Australian and New Zealand Intensive Care Society (ANZICS) has reported a total of 84 ICU admissions for influenza in 2010, of which 2 occurred during this reporting period. Of these ICU admissions, 58 have been associated with pandemic (H1N1) 2009, 10 with influenza A (not subtyped), 2 with seasonal A/H3N2, 12 with seasonal H1N1 (these may be pandemic cases, yet to be confirmed) and 2 with influenza not typed (Figure 14).

    Of the 58 pandemic (H1N1) 2009 ICU admissions in 2010, 48 had known co-morbidities and the median age at admission was 45 years (range 6-80).

    Figure 14. Number of ICU admissions for influenza, ANZICS, Australia, 1 January to 3 September 2010

    Figure 14. Number of ICU admissions for influenza, ANZICS, Australia, 1 January to 3 September 2010


    Source: Australian and New Zealand Intensive Care Society (ANZICS) data base


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    Deaths associated with influenza and pneumonia

    Nationally reported pandemic (H1N1) 2009 deaths
    In 2010, seven pandemic influenza related deaths have been notified to the NNDSS. The deaths occurred in late May, July and August, with a median age of 53 years. All cases were reported as having underlying risk factors.

    NSW
    Death registration data show that for the week ending 20 August 2010, there were 128 pneumonia or influenza associated deaths per 1,000 deaths in NSW, which is below the seasonal threshold for this period of 145 per 1,000 deaths (Figure 15).

    NSW death registration data cross-matched with laboratory cases of influenza show 13 people with laboratory confirmed influenza have died up to 27 August 2010. All 13 cases had multiple comorbidities and were aged 50 years and over.1

    Figure 15. Rate of deaths classified as influenza and pneumonia from the NSW Registered Death Certificates, 2005 to 20 August 2010

    Figure 15. Rate of deaths classified as influenza and pneumonia from the NSW Registered Death Certificates, 2005 to 20 August 2010

    Source: NSW ‘Influenza Monthly Epidemiology Report’


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    3. Virology

    Typing and antigenic characterisation - WHO Collaborating Centre for Reference & Research on Influenza (WHO CC) in Melbourne

    From 1 January to 5 September 2010, there were 459 Australian influenza isolates subtyped by the WHO CC (Table 3).

    Table 3. Typing of influenza isolates from the WHO Collaborating Centre, from 1 January 2010 to 5 September 2010

    Type/Subtype
    ACT NSW NT Qld SA Tas Vic WA TOTAL
    A(H1N1)
    0
    0
    0
    0
    0
    0
    0
    0
    0
    Pandemic (H1N1) 2009
    16
    12
    62
    70
    77
    1
    108
    71
    417
    A(H3N2)
    2
    1
    0
    5
    0
    2
    7
    11
    28
    B
    0
    2
    0
    0
    0
    0
    11
    1
    14
    Total
    18
    15
    62
    75
    77
    3
    126
    83
    459


    SOURCE: WHO CC
    Please note: There may be up to a month delay on reporting of samples.
    Isolates tested by the WHO CC are not necessarily a random sample of all those in the community, hence proportions of pandemic (H1N1) 2009 to seasonal are not representative of the proportions circulating.



    Antigenic characterisation of 192 pandemic (H1N1) 2009 isolates has shown 176 to be the A/California/7/2009-like strain and one a low reactor version of this strain. Antigenic characterisation of 12 type A/H3N2 isolates has shown one to be the A/Perth/16/2009-like and 11 to be the A/Perth/16/2009-like low reactor versions of the strain. One isolate was antigenically characterised as a low-reactor version of B/Florida/4/2006-like and two were characterised as B/Brisbane/60/2008-like.
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    International Virology

    In the week ending 14 August 2010, based on FluNet reporting by National Influenza Centres from 25 countries, 9% of positive specimens were typed as influenza B and 91% were typed as influenza A. Co-circulation of pandemic (H1N1), A/H3N2 and influenza B viruses was reported from Australia, China, India and Chile. Globally, 71% of sub-typed influenza A viruses were pandemic (H1N1) 2009, which is the predominant virus in New Zealand and India. Sporadic activity of pandemic influenza A(H1N1), influenza B and/or A(H3N2) was detected in some countries.

    In China, influenza B accounted for 15.4% of all influenza viruses detected in the week to 22 August 2010. From 1 January 2010 to 22 August 2010, 3,869 influenza B viruses have been antigenically characterised. Of those, 3,382 (87.4%) were B/Victoria viruses, including 38.6% (1307) related to B/Malaysia/2506/2004-like and 61.4% (2075) related to B/Brisbane/60/2008 (included in 2010 Southern Hemisphere seasonal influenza vaccine). The remaining 487 (12.6%) were B/Yamagata viruses related to B/Florida/4/2006-like.2
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    Antiviral Resistance – Pandemic (H1N1) 2009

    Up to 18 August 2010, the WHO has reported a total of 304 oseltamivir resistant pandemic (H1N1) 2009 viruses since May 2009 with two new cases of resistance reported in the most recent WHO reporting week. All of these isolates except one showed the same H275Y mutation and all remain sensitive to zanamivir. One isolate had an amino acid mutation at position 223 in the neuraminidase and was determined to have reduced susceptibility to zanamivir and oseltamivir.2

    The WHO Collaborating Centre in Melbourne has reported that from 1 January 2010 to 3 September 2010, no isolates (out of 195 tested) have shown resistance to oseltamivir or zanamivir by enzyme inhibition assay (EIA) and two isolates (out of 41 tested) have shown the H275Y mutation known to confer resistance to oseltamivir.
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    4. International Influenza Surveillance

    The WHO has advised that the world is no longer in phase 6 of influenza pandemic alert, and will now move into the post pandemic period.3 The WHO has reported that as of 1 August 2010 there have been over 18,449 deaths associated with pandemic (H1N1) 2009 influenza worldwide since April 2009. Up to 27 August, WHO has reported that pandemic (H1N1) 2009 virus transmission remains locally intense in parts of India, New Zealand and more recently Australia.4
  • Northern Hemisphere
    • In India, community transmission of pandemic (H1N1) 2009 remained intense in several western and southern states as well as in the capital. The western state of Maharashtra continues to record the most intense activity, however the rate of reported new cases appears to have slowed during mid-August 2010, suggesting that current epidemic activity may be peaking. Since late July 2010 the vast majority of influenza detections have been H1N1 2009.
  • Southern Hemisphere
    • In New Zealand, pandemic (H1N1) 2009 virus transmission remains active and locally intense. The national ILI consultation rate has decreased in this reporting week, however, is above the seasonal baseline for the fifth consecutive week.5 Several areas are reporting local rates of ILI consultations that match or surpass national rates reported at the peak of last winter’s pandemic wave. The vast majority of detections during the current epidemic period have been pandemic (H1N1) 2009.4
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    5. Data considerations

    The information in this report is reliant on the surveillance sources available to the Department of Health and Ageing. As access to sources increase and improve, this report will be refined and additional information will be included.

    This report aims to increase awareness of pandemic (H1N1) 2009 and seasonal influenza in Australia by providing an analysis of the various surveillance data sources throughout Australia. While every care has been taken in preparing this report, the Commonwealth does not accept liability for any injury or loss or damage arising from the use of, or reliance upon, the content of the report. Delays in the reporting of data may cause data to change retrospectively. For further details about information contained in this report please contact the Influenza Team through flu@health.gov.au

    On 17 June 2009 Australia commenced the transition to a new response phase called PROTECT, in which laboratory testing is directed towards people with moderate or severe illness; those more vulnerable to severe illness; and those in institutional settings. This means that the number of confirmed cases does not reflect how many people in the community have acquired pandemic (H1N1) 2009 infection.
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    Geographic spread of influenza and ILI – Jurisdictional Surveillance

    Jurisdictions report activity levels (in line with the definitions below) on a fortnightly basis, based on laboratory-confirmed notifications, various syndromic surveillance systems, outbreak reporting and rumour surveillance.

    Activity level
    Definitions:
    No activity No influenza or ILI activity
    Syndromic only an increase in syndromic surveillance systems with no laboratory confirmed cases
    Sporadic small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak during the reporting period, but no increase in cases in syndromic surveillance systems
    Local outbreaks of influenza or increases in cases in syndromic surveillance systems and recent laboratory-confirmed influenza in a single region of the state
    Regional outbreaks of influenza or increases in cases in syndromic surveillance systems and a recent laboratory confirmed influenza in at least two but less than half the regions of the state
    Widespread outbreaks of influenza or increases in cases in syndromic surveillance systems and recent laboratory-confirmed influenza in at least half the regions of the state.


    Sentinel General Practice Surveillance

    The Australian Sentinel Practices Research Network (ASPREN) has Sentinel GPs who report ILI presentation rates in NSW, NT, SA, ACT, VIC, QLD, TAS and WA. As jurisdictions joined ASPREN at different times and the number of GPs reporting has changed over time, the representativeness of ASPREN data in 2010 may be different from that of previous years. ASPREN data and VIDRL influenza surveillance data are sent to the Surveillance Branch on a weekly basis. Further information on Sentinel GPs’ Influenza Surveillance and ASPREN activities are available at www.dmac.adelaide.edu.au/aspren
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    Sentinel ED data

    WA - ED surveillance data are extracted from the ‘Virus Watch’ Report. This report is provided weekly. The Western Australia Influenza Surveillance Program collects data from eight Perth EDs.

    NSW - ED surveillance data are extracted from the ‘Weekly Influenza Report, NSW’. The New South Wales Influenza Surveillance Program collects data from 56 EDs across New South Wales.

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    Flu T racking

    FluTracking is a project of the University of Newcastle, the Hunter New England Area Health Service and the Hunter Medical Research Institute. FluTracking is an online health surveillance system to detect epidemics of influenza. It involves participants from around Australia completing a simple online weekly survey, which collects data on the rate of ILI symptoms in communities.

    Data have been provided weekly and have been presented in this report to show the pattern of self reported ILI in the community over the 2009 season.

    Further information on FluTracking is available at www.flutracking.net/index.html
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    National Health Call Centre Network

    A national organisation provides call centre data for calls relating to ILI or influenza. Data are provided daily and are collated weekly and have been presented in this report to show the pattern of calls to this Call Centre over the 2009 and 2010 season. Data is available for all jurisdictions other than QLD and VIC.

    Absenteeism

    A national organisation provides data on the number of employees who have been on sick leave for a continuous period of more than three days. These data are not influenza or ILI specific and absenteeism may be a result of other illnesses.

    Sentinel Laboratory Surveillance data

    Laboratory testing data are provided weekly directly from PathWest (WA), VIDRL (VIC), ICPMR (NSW), sentinel Tasmanian laboratories, and ASPREN (national).

    National Notifiable Diseases Surveillance System (NNDSS)

    Laboratory confirmed influenza (all types) is notifiable in all jurisdictions in Australia. Confirmed cases of influenza are notified through NNDSS by all jurisdictions except NSW. NSW data are sourced from NetEpi.

    NetEpi

    In 2009, NetEpi, a web-based outbreak case reporting system for pandemic (H1N1) 2009, was used as the primary source of enhanced data on confirmed cases, hospitalisations and ICU admissions in all jurisdictions. In 2010, only data for NSW are sourced from NetEpi.

    Analyses of Australian cases are based on the diagnosis date, which is the earliest of the onset date, specimen date or notification date.

    Data Analysis

    Analysis of confirmed influenza cases is conducted on combined NetEpi and NNDSS data. Analysis of morbidity (hospitalisations and ICU admissions) and mortality data in 2009 has been conducted on combined NetEpi and QLD hospitalisation data.

    FluCAN

    The Influenza Complications Network (FluCAN) collects detailed clinical information on all hospitalised cases of influenza and pneumonia from a sample of 15 sentinel hospitals across Australia. The data for this reporting period are sourced only from 14 hospitals.
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    APSU

    The Australian Paediatric Surveillance Unit collects clinical information on hospitalised cases of children aged 15 years and under with complications due to influenza infection. Approximately 1300 (80% of total) Paediatric clinicians registered with the Paediatrics and Child Health Division of the Royal College of Physicians, respond to APSU report cards. These report cards seek information regarding hospitalisations relating to 12 diseases or conditions, including influenza.

    Australian and New Zealand Intensive Care Society data (ANZICS data)

    The Australian and New Zealand Intensive Care Society provide data from a `near real time` registry of patients admitted to Australian ICUs. This documents the key factors influencing mortality, as well as the need for hospitalisation and mechanical ventilation. Information collected includes person characteristics and information on relevant co-morbidities, nature of the clinical syndrome associated with pandemic (H1N1) 2009, major therapeutic interventions from which organ failure outcomes can be imputed, vaccination status and vital status at time of ICU discharge and hospital discharge.

    WHO Collaborating Centre for Reference & Research on Influenza (WHO CC)

    Data are provided weekly to the Surveillance Branch from the WHO CC.

    Deaths associated with influenza and pneumonia

    Nationally reported pandemic (H1N1) 2009 deaths are notified by jurisdictions to the Commonwealth Department of Health and Ageing as they occur.

    NSW influenza and pneumonia deaths data are collected from the NSW Registry of Births, Deaths and Marriages. Figure 14 is extracted from the ‘Weekly Influenza Report, NSW’
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    6. References


    1. NSW Influenza Monthly Epidemiology Report, August 2010. Available from http://www.health.nsw.gov.au/publichealth/infectious/reports/influenza_report_august.asp Accessed 3 September 2010.
    2. Chinese National Influenza Centre Influenza Weekly Report 22 August 2010. Available from: http://www.cnic.org.cn/eng/ Accessed 2 September 2010.
    3. World Health Organisation virtual press conference, 10 August 2010. Accessed 11 August 2010. Available from http:// www.who.int/en/
    4. WHO Pandemic (H1N1) 2009 - Update 115 & Virological Surveillance Weekly Update. Available from http://www.who.int/csr/don/en/ Accessed 2 September 2010.
    5. New Zealand Influenza Weekly Update – 29 August 2010. Available from http://www.surv.esr.cri.nz/virology/influenza_weekly_update.php Accessed 7 August 2010.