Australian influenza report 2009 - 31 October to 6 November 2009 (#26/09)

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. It is produced weekly from May to October. A more in-depth end of season report is also published in Communicable Diseases Intelligence.

Page last updated: 16 November 2009

Report No. 26
Week ending 6 November 2009

A print friendly version of this report is available as a PDF (154 KB)

Is the situation changing?
Indicated by: laboratory confirmed cases reported to NetEpi/NNDSS; Sentinel syndromic surveillance systems GP Sentinel ILI Surveillance; and ED presentations of ILI at sentinel hospitals (NSW and WA). Laboratory data are used to determine the proportion of influenza and pandemic (H1N1) 2009 circulating in the community.
How severe is the disease, and is severity changing?
Indicated by: number of hospitalisations, ICU admissions and deaths
Is the virus changing?
Indicated by: emergence of drug resistance or gene drift/shift from laboratory surveillance.

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Latest data

  • As of 6 November 2009 there had been 37,127 confirmed cases of pandemic (H1N1) 2009 and 189 deaths reported in Australia. The number of confirmed cases is lower than that reported in the previous week following the identification and removal of some incorrectly entered cases. In addition, NSW has reported two deaths associated with pandemic (H1N1) 2009 infections related to adult males who died in September 2009.

      New Hosp
    (indigenous)
    New ICU
    (indigenous)
    New Deaths
    (indigenous)
    Cum Hosp
    (indigenous)
    Cum ICU
    (indigenous)
    Cum Deaths
    (indigenous)
    ACT
    0
    (0)
    0
    (0)
    0
    (0)
    61  
    (0)
    1
    (0)
    2
    (0)
    NSW
    0
    (0)
    0
    (0)
    0
    (0)
    1288 
    (101)
    251
    (-)
    53
    (5)
    NT
    0
    (0)
    0
    (0)
    0
    (0)
    378   
    (319)
    48
    (36)
    6
    (5)
    Qld
    0
    (0)
    0
    (0)
    0
    (0)
    1243 
    (158)
    162
    (-)
    41
    (7)
    SA
    0
    (0)
    0
    (0)
    0
    (0)
    503 
    (44)
    78
    (9)
    29
    (5)
    Tas
    0
    (0)
    0
    (0)
    0
    (0)
    108
    (2)
    9
    (0)
    7
    (0)
    Vic
    -
    (-)
    -
    (-)
    -
    (-)
    514
    (4)
    118
    (-)
    24
    (0)
    WA
    0
    (0)
    0
    (0)
    0
    (0)
    863
    (165)
    78
    (7)
    27
    (3)
    Aus
    0
    (0)
    0
    (0)
    0
    (0)
    4958
    (793)
    745
    (52)
    189
    (25)

    NOTE: Numbers in brackets, eg (0), indicate Indigenous numbers Victoria is no longer reporting current hospitalisations



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    Key Issues

  • Pandemic influenza activity continues to increase across many countries in temperate parts of the Northern Hemisphere, signalling an unusually early start to the winter influenza season. Activity has been particularly intense in North America and across Northern and Eastern Europe (including Ukraine and Belarus).
  • Surveillance of pandemic influenza activity in Australia and in other countries has not generated any signals to suggest any significant changes in the epidemiology, clinical severity or transmissibility of the pandemic (H1N1) 2009 virus.
  • There has been no indication of a significant increase in the incidence of antiviral-resistant pandemic (H1N1) 2009 strains.
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    Summary

    Is the situation changing?

    As of 6 November 2009:
  • There were 37,127 confirmed cases of pandemic (H1N1) 2009 in Australia.
  • The number of new confirmed pandemic (H1N1) 2009 cases has decreased nationally with a number of jurisdictions reporting no new notifications in the last week. There were no new hospitalisations reported in the reporting period.
  • Two additional deaths associated with pandemic (H1N1) 2009 infections have been reported by NSW. These relate to two adult males with vulnerable co-morbidities who died in September 2009.
  • National influenza activity continued to decrease.
  • - Influenza-like illness (ILI) presentation rates to General Practitioners at a national level were below the baseline levels reached at the end of the 2007 and 2008 influenza seasons. Rates remained stable in most jurisdictions, although some reported rates slightly above background levels.
  • - FluTracking surveillance for the week ending 1 November 2009indicated that ILI activity remained at low levels in all jurisdictions.
  • - Enquiries to the National Health Call Centre Network (NHCCN) regarding ILI continue to drop and are at low levels.
  • - Absenteeism rates have increased slightly in the last week and currently are at levels similar to those seen at the same time period in 2007.
  • The number of respiratory tests positive for influenza A and pandemic (H1N1) 2009 are now very low. Type A influenza is the predominant seasonal influenza type reported by all jurisdictions and the pandemic A/H1N1 2009 strain has almost replaced the current seasonal H1N1 strain. Of the seasonal influenza A notifications, influenza A/H3N2 remains the predominant strain reported by most jurisdictions.
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    How severe is the disease? a

  • Analysis of data to 23 October 2009 indicated that:
  • - The number of people with pandemic (H1N1) 2009 requiring hospitalisation continued to decrease. In total, 4,833 people had been hospitalised, with 13% admitted to Intensive Care Units. Of the hospitalisations for which Indigenous status is known, 803 (21%) have been Indigenous Australians. Pregnant women represented 27% of all hospitalisations for pandemic (H1N1) 2009 of women aged between 15 and 44 years.
  • - Of the 186 fatal cases associated with pandemic (H1N1) 2009, 3 (4% of female deaths) were pregnant women and 24 (13%) were Indigenous Australians.
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    Is the virus changing?

  • In Australia, 2 of 347 pandemic (H1N1) 2009 viral isolates tested by NA enzyme inhibition assay were resistant to oseltamivir, and the H275Y resistance mutation was found in 5 of 152 clinical specimens tested.
  • To date, the WHO has received formal notification of 42 cases of oseltamivir resistance pandemic (H1N1) 2009 viruses worldwide.
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    International influenza surveillance

  • The number of human cases of pandemic (H1N1) 2009 continues to increase in many countries. As at 1 November 2009, the WHO reported over 482,300 confirmed cases and at least 6,071 deaths associated with pandemic (H1N1) 2009 worldwide.
  • In the temperate zone of the Northern Hemisphere, ILI activity continues to intensify marking an unusually early start to winter influenza season in some countries. In the temperate regions of the Southern Hemisphere influenza transmission has largely returned to baseline (Chile, Argentina, and New Zealand) or has declined substantially (Australia and South Africa).

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    Key Points

    1. Influenza activity in Australia </h2>]

    Laboratory Confirmed Cases

    There have been 7 new laboratory confirmed pandemic (H1N1) 2009 notifications in the last reporting week, with 5 jurisdictions reporting no new notifications. As of 6 November 2009 there were 37,127 confirmed cases of pandemic (H1N1) 2009 in Australia, including 189 pandemic influenza-associated deaths.

    Figure 1. Laboratory confirmed cases of pandemic (H1N1) 2009 in Australia, to 6 November 2009 by jurisdiction

    Figure 1. Laboratory confirmed cases of pandemic (H1N1) 2009 in Australia, to 6 November 2009 by jurisdiction

    Source: NetEPI database



    Figure 2. Influenza activity in Australia, by reporting week, years 2007, 2008 and 2009*

    Figure 2. Influenza activity in Australia, by reporting week, years 2007, 2008 and 2009

    * Data on pandemic (H1N1) 2009 cases is extracted from NetEPI; data on seasonal influenza is extracted from NNDSS.
    Sources: NNDSS and NetEPI databases


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    Influenza-Like Illness b

    Sentinel General Practice Surveillance

    Combined data available from the Australian Sentinel Practices Research Network (ASPREN), the Northern Territory GP surveillance system and VIDRL, up until 1 November 2009, show that nationally, influenza like Illness (ILI) consultation rates remained stable this reporting period and were below levels seen at the end of the 2007 and 2008 seasons (Figure 3).

    In the last week, the presentation rate to sentinel GPs in Australia was approximately 5 cases per 1,000 patients seen.

    Figure 3. Weekly rate of ILI reported from GP ILI surveillance systems from 2007 to 1 November 2009*

    Figure 3. Weekly rate of ILI reported from GP ILI surveillance systems from 2007 to 1 November 2009

    * Delays in the reporting of data may cause data to change retrospectively. As data from the NT and the VIDRL surveillance systems are combined with ASPREN data, rates may not be directly comparable across 2007, 2008 and 2009. SOURCE: ASPREN, NT, VIDRL



    Further analysis of the ILI data during this period indicates that levels remained stable or decreased in most jurisdictions; however this is above background levels in some jurisdictions (Figure 4). An increase was observed in the Australian Capital Territory, and slight increases occurred in Western Australia and New South Wales.

    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 *


    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 tasmania
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    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 australian capital territory
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    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 western australia
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    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 victoria
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    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 new south wales
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    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 queensland
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    Figure 4. Weekly rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 1 November 2009 northern territory

    SOURCE: NT Surveillance[ </p>]

    *Care should be taken when interpreting graphs due to lags in reporting in some instances and small numbers being reported from jurisdictions. The last data point may be modified in future reports.


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    Emergency departments (EDs)

    ILI presentations to EDs remained stable across reporting systems in New South Wales and Western Australian this reporting period.
    New South Wales: the number of ILI presentations and admissions to EDs is continuing to decrease, however numbers are higher than during the same period in the previous year.
    Western Australia: the number of ILI presentations reported in EDs are elevated above baseline levels but have remained stable during this reporting period.

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    FluTracking

    FluTracking, a national online tool for collecting data on ILI, reported that activity remained at low levels nationally and in the four States with sufficient data for reporting in the week ending 1 November 2009.

    Figure 5. Rate of ILI symptoms and absence from regular duties among Flutracking participants by week, from week ending 3 May 2009 to week ending 1 November 2009

    Figure 5. Rate of ILI symptoms and absence from regular duties among Flutracking participants by week, from week ending 3 May 2009 to week ending 1 November 2009

    Source: Flutracking Interim Weekly Report



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    National Health Call Centre Network

    The number of calls related to ILI to the National Health Call Centre Network (NHCCN) remained stable, with 85 calls in the week ending 6 November 2009. At the peak, the NHCCN received approximately 1900 ILI-related calls per week. The number of calls currently being received is low but not yet at pre-pandemic levels (Figure 6).

    Figure 6. Number of calls to the National Health Call Centre Network (NHCCN) related to ILI, Australia, 1 January 2009 (Wk1) to 6 November 2009 (Wk45)

    Figure 6. Number of calls to the National Health Call Centre Network (NHCCN) related to ILI, Australia, 1 January 2009 (Wk1) to 6 November 2009

    SOURCE: NHCCN data




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    Absenteeism

    The most recent available data indicates that in the week ending 28 October 2009, absenteeism rates nationally increased slightly, however absenteeism rates in recent weeks are similar to those seen at the same time in previous years (Figure 7).

    Figure 7. Rates of absenteeism of greater than 3 days absent, National employer, 1 January 2007 to 28 October 2009, by week.

    Figure 7. Rates of absenteeism of greater than 3 days absent, National employer, 1 January 2007 to 28 October 2009, by week

    SOURCE: Absenteeism data



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    Sentinel Laboratory Surveillance - confirmed influenza notifications

    Results from sentinel laboratory surveillance systems continued to show very few samples are being confirmed positive for Influenza A virus, but of those that were positive the majority were further subtyped as pandemic (H1N1) 2009 strains (Table 1).

    Table 1. Laboratory Respiratory tests that tested positive for influenza A and pandemic (H1N1) 2009

      ASPREN* – national VIDRL^ NSW# WA NIC NT (reported by WA NIC)
    Latest report

     

     

     

     

     

    Number of specimens tested

    10
    6
    (at 1/11)
    531
    (at 30/10)
    185
    (at 7/11)
    n/a
    Number tested which were Influenza A
    0
    0
    2
    4
    2
    Number tested which were pandemic (H1N1) 2009
    0
    0
    2
    2
    2
    Previous report
    Number of specimens tested
    7
    5
    (at 25/10)
    540
    (at 23/10)
    177
    (at 31/10)
    0
    Number tested which were Influenza A
    0
    0
    1
    4
    0
    Number tested which were pandemic (H1N1) 2009
    0
    0
    1
    4
    0

    *ASPREN tests are collected every Tuesday. Results are reported for a rolling fortnight as data changes retrospectively.^VIDRL Influenza Report available from : http://www.vidrl.org.au/surveillance/flu%20reports/flurpt09/flu09.html
    #NSW Influenza Report available from : http://www.emergency.health.nsw.gov.au/swineflu/index.asp



    From 1 January to 6 November 2009, type A was the predominant seasonal influenza type reported by all jurisdictions. Of the type A notifications for which there was subtyping information in NNDSS, the ratio of seasonal H1N1 to H3N2 was 1:2.3.


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    Key Points

    2. Overview of pandemic (H1N1) 2009 severity - to 23 October 2009 <a href="#footnote"><sup>c</sup></a> </h2>]While pandemic (H1N1) 2009 is generally considered a mild disease at the community level, it has had serious consequences at the acute end of the disease. Figures of hospitalisations, ICU admissions and deaths are currently used as indicators to provide evidence on the severity of the disease in Australia (Table 2).
    Of particular note is the difference in the age distribution of the novel influenza virus to seasonal influenza and the increasing median age as the severity of the disease progresses: 21 years for all confirmed cases; 31 years for hospitalised cases; 45 years for ICU cases; and 54 years for deaths.

    The disease has also had a differential impact upon Indigenous Australians, who are ten times more likely to be hospitalised with the disease than non-Indigenous Australians. Pregnant women are also over-represented in the more severe cases with pregnancy being a risk factor in 27% of women aged 15 to 44 years who require hospitalisation for the disease.

    Table 2. Summary of severity indicators of pandemic (H1N1) in Australia, to 23 October 2009 c

      Confirmed pandemic (H1N1) 2009 cases Hospitalised cases ICU cases Deaths
    Total number
    37,149
    13% (4,833/37,149 confirmed cases)
    13% (650/4,833 hospitalisations)
    186
    Crude rate per 100,000 population
    173.1
    22.6
    3.2
    0.8
    Median age (years)
    21
    31
    45
    54
    Females
    51% (18,125/37,029)
    51% (2,455/4,833)
    53% (347/650)
    42% (78/186)
    Vulnerable groups (Indigenous, pregnant & individuals with at least 1 comorbidity)
    n/a
    57% (2,755/4,833)
    74% (484/650)
    67% (125/186)
    Indigenous people~
    11% (3,822/34,344)
    20% (803/3,908)
    20% (100/499)
    13% (24/186)
    Pregnant*
    n/a
    27% (278/1,030 hospitalised females aged
    15-44 years)
    17% (47/278 hospitalised pregnant women)
    4% (3/78 female deaths)
    Cases with at least 1 co-morbidity
    n/a
    49% (2,382/4,833)
    71% (460/650)
    65% (120/186)

    #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 is not always complete for each summarised figure.
    ~The denominator for this row is the number of confirmed cases for which Indigenous status is known.
    * Includes women in the post-partum period


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    3. Virology

    Antigenic characteristics - WHO Collaborating Centre for Reference & Research on Influenza (WHO CC) in Melbourne

    In 2009 up to 6 November 2009, 1,209 Australian influenza isolates have been subtyped by the WHO CC (Table 3). Of these, 621 influenza isolates have been antigenically characterized, with 62% confirmed as pandemic A/H1N1 2009 (A/California/7/2009-like).

    Table 3. Typing of Influenza isolates from the WHO Collaborating Centre, 1 Jan. – 6 Nov. 2009

    Antigenic characterization
    ACT NSW NT Qld SA Tas Vic WA TOTAL
    A(H1N1)
    2
    15
    0
    29
    18
    1
    11
    27
    103
    Pandemic (H1N1) 2009
    41
    64
    140
    75
    75
    9
    175
    230
    809
    A(H3N2)
    16
    95
    8
    41
    2
    8
    38
    68
    276
    B
    0
    8
    0
    1
    0
    0
    4
    8
    21
    Total
    59
    182
    148
    146
    95
    18
    228
    333
    1209

    SOURCE: WHO CC
    Please note: There may be up to a months delay on reporting of samples
    Isolates tested by the WHO CC are not a random sample of all those in the community hence proportions of pandemic (H1N1) 2009 to seasonal are not representative of the proportions circulating. Early in the pandemic all influenza A untypeable samples were sent to the WHO CC for testing and later many pandemic (H1N1) 2009 positive samples were sent for confirmation, resulting in biases in the data.



    In general, seasonal influenza A strains circulating this influenza season are the same as strains in the vaccine, with the A(H3N2) virus drifting. Influenza B strains match more closely with those in the 2009-2010 Northern Hemisphere vaccine and may be drifting.

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    Antiviral Resistance

    Pandemic (H1N1) 2009

    To date, the WHO has received formal notification of 42 cases of oseltamivir resistant pandemic (H1N1) 2009 viruses worldwide (Table 4).1 The isolates have a mutation in the neuraminidase that confers resistance to oseltamivir (referred to as H275Y), but they remain sensitive to zanamivir.

    Table 4. Worldwide oseltamivir resistant viruses reported to 6 November 2009

    Description
    Number
    Associated with the use of oseltamivir for post exposure prophylaxis
    12
    Associated with the use of oseltamivir treatment in patients with severe immunosuppression
    6
    Isolated from samples from patients receiving oseltamivir treatment
    4
    Isolated from patients who were not taking oseltamivir for either treatment or prophylaxis.
    2
    Unspecified
    18
    Total
    42

    The WHOCC in Melbourne has reported 2 isolates which tested resistant to oseltamivir by NA enzyme inhibition assay and 5 specimens with the H275Y mutation (Table 5).

    Table 5. Resistance testing of Australian pandemic (H1N1) 2009 viruses

      No. tested Resistant/positive for H275Ymutation
    Viral isolates tested in NA enzyme inhibition assay
    347
    2*
    Clinical specimens tested for the H275Y mutation known to confer resistance to oseltamivir
    152
    5

    *This figure represents two isolates from the same patient, both of which were found to contain the H275Y mutation.[ </p>]
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    Seasonal Influenza

    The last WHO report on resistance of seasonal strains to oseltamivir was released on 4 June 2009, during the Northern Hemisphere influenza season 2008-2009 and stated that 96% of seasonal influenza A (H1N1) isolates tested from 36 countries worldwide were resistant to oseltamivir.2

    Table 6. Resistance Testing – Seasonal Influenza - Global

    Country Percentage of H1N1 viruses Percentage of A(H3N2) Percentage of B viruses
    Australia (since 1 January 2009)
    97.2% (36/37) resistant to oseltamivir
    0% (0/40) resistant to oseltamivir
    0% (0/6) resistant to oseltamivir
    New Zealand (up to 1 November 2009)3
    100% (53/53) resistant to oseltamivir
    n/a
    n/a

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    4. International Influenza Surveillance d

    As at 1 November 2009, the WHO Regional Offices reported over 482,300 confirmed cases and at least 6,071 deaths associated with pandemic (H1N1) 2009 worldwide.4 The number of human cases of pandemic (H1N1) 2009 is still increasing in many countries.
    In the temperate zone of the Northern Hemisphere, influenza like illness (ILI) activity continues to intensify marking an unusually early start to winter influenza season in some countries. In the temperate regions of the Southern Hemisphere influenza transmission has largely returned to baseline (Chile, Argentina, and New Zealand) or has declined substantially (Australia and South Africa).

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    Northern America

  • – Intense and persistent influenza transmission continues to be reported in without evidence of a peak in activity.
  • The USA reported increased and widespread influenza activity during week 43 (week ending 31 October 2009). The proportion of outpatient visits for ILI was above the national baseline. The proportion of deaths attributed to pneumonia and influenza was above the epidemic threshold. Eighteen influenza-associated paediatric deaths were reported of which 15 were associated with pandemic (H1N1) 2009 influenza A virus infection and 3 were associated with an influenza A virus for which the subtype was undetermined. Over 99% of all subtyped influenza A viruses being reported to CDC were 2009 influenza A (H1N1) viruses.5
  • Canada has reported a considerable and widespread increase in the influenza activity level in the week ending 31 October 2009 (week 43), with the proportion of positive influenza tests of more than 35%, the national ILI consultation rate higher than 100 per 1,000 visits and over 700 influenza outbreaks reported of which most occurred in schools. The pandemic (H1N1) 2009 strain accounted for nearly 100% (99.7%) of the positive influenza A subtyped specimens. The intensity of Pandemic (H1N1) 2009 in the population was high, with 661 hospitalizations and 8 deaths reported in week 43. Numbers of new hospitalizations were more than three times higher than the previous week . 6

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    Central and South America

  • - Active influenza transmission and increasing levels of respiratory diseases continues to be reported in parts of the Caribbean, including in Cuba, Haiti, and other Caribbean Epidemiology Centre countries. Most other countries in the tropical region of Central and South America continue to report declining influenza activity . 7
  • Mexico has reported more confirmed cases since September than during the springtime epidemic. As at 10 November 2009, confirmed cases of pandemic (H1N1) 2009 in Mexico (59,148) and related deaths (433) continue to increase .[ <sup>8</sup>]

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    Europe

  • - Pandemic influenza activity continues to increase across many countries, signalling an unusually early start to the winter influenza season. Active circulation of virus marked by high proportions of sentinel respiratory samples testing positive for influenza has been reported in Belgium (69%), Ireland (55%), Netherlands (51%), Norway (66%), Spain (46%), Sweden (33%), the United Kingdom (Northern Ireland: 81%), and Germany (27%). In addition, there is evidence of increasing and active transmission of pandemic influenza virus across Northern and Eastern Europe (including Ukraine and Belarus), and eastern Russia.9
  • In the week ending 5 November 2009 (Week 45), pandemic influenza activity varied across the UK. The weekly influenza/ILI consultation rates decreased to 37.7 per 100,000 consultations, though remained above the winter baseline activity threshold of 30 per 100,000 consultations, particularly in England, Scotland and Northern Ireland. The main influenza virus circulating in the UK continues to be the pandemic (H1N1) 2009 strain, with few influenza H1 (non-pandemic), H3 and B viruses detected. The cumulative number of deaths reported due to pandemic (H1N1) 2009 in the UK is 151. There was a total of 1,431 new patients hospitalised in England with suspected pandemic influenza in the week from 29 October to 4 November, an increase from 1,200 in the previous week. The highest hospitalisation rates have consistently been in the under 5-year age group, and have increased in all age groups recently.10
  • There was clear evidence of continuing widespread influenza activity in Ireland, with a small decrease noted during week 44 (week ending 1 November 2009). The sentinel GP influenza like illness (ILI) consultation rate was 178.5 per 100,000 population in week 44 compared to the previous rate of 201.2 per 100,000 reported during week 43. The highest sentinel GP age-specific ILI consultation rates occurred in the 0-4 year age group. The number of hospitalised cases of confirmed pandemic (H1N1) 2009 increased by over 6%, from 109 in week 43 to 116 cases in week 44. Pandemic (H1N1) 2009 was the only influenza virus circulating in week 44. Children and young adults remain the most affected groups; 81.4% of cases are less than 35 years of age.11
  • The World Health Organization (WHO) has sent a team of experts to investigate the clinical and epidemiological features of the outbreak in Ukraine, where the level of influenza activity is increasing rapidly. As the pandemic virus has rapidly become the dominant influenza strain worldwide, it can be assumed that most cases of influenza in Ukraine are caused by the pandemic (H1N1) virus. As of 2 November, the Ministry of Health of Ukraine, has reported more than 250,000 cases of ILI, where over 2,300 people have been hospitalised with suspected pandemic (H1N1) 2009 virus infections, 235 of them requiring intensive care and 70 people have died from acute respiratory illness . 12

    Africa

  • - Influenza virus isolates from sub-Saharan Africa are predominantly pandemic H1N1 virus but some seasonal H3N2 has been detected even in recent weeks.

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    Asia

  • - In East Asia, intense and increasing influenza activity continues to be reported in Mongolia. In Western Asia, increasing activity has been reported in Oman and Afghanistan. With the exception of Nepal, Sri Lanka, and Cambodia, overall transmission continues to decline in most but not all parts of tropical South and Southeast Asia.
  • In China, after an earlier wave of mixed influenza activity (seasonal H3N2 and pandemic H1N1), pandemic H1N1 influenza activity now predominates and is increasing.
  • In Japan, sharp increases in pandemic influenza activity continue to be reported, with the highest rates of illness being reported on the northern island.

    Oceania


  • Influenza activity continues to decrease in New Zealand in the week ending 1 November (week 44), with a decrease in ILI consultation rates of 25.2 per 100,000 population from 27.7 in the previous week. The highest ILI consultation rates have been reported among children and teenagers aged 0 to 19 years.13

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    5. Pandemic (H1N1) 2009 virus in animals

    Since the new pandemic H1N1 2009 virus emerged in April 2009, infections in different species of susceptible animals (pig, turkey, ferret, and cat) have been reported. Limited evidence suggests that these infections occurred following direct transmission of the virus from infected humans. These isolated events have had no impact on the dynamics of the pandemic, which is spreading readily via human-to-human transmission. As human infections become increasingly widespread, transmission of the virus from humans to other animals is likely to occur with greater frequency. Unless the epidemiology of the pandemic changes, these will continue to pose no special risks to human health.14

    The World Organisation for Animal Health (OIE) has reported that notifications of pandemic (H1N1) 2009 virus infection in new animal species that have been received are to be expected and are a sign of good animal disease surveillance. OIE states that there has to date been no evidence that has suggested that animals play any particular role in the epidemiology or the spread of the pandemic (H1N1) 2009 virus among humans. Instead, investigations led by competent national authorities point to possible human–to–animal transmission in most cases. For this reason, the OIE considers that it is sufficient to certify the healthy state of animals for international trade during the relevant period before their exportation and maintains its position that no specific measures, including laboratory tests, are required for international trade in live pigs and other susceptible animal species and/or their products.15
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    6. 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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    NetEpi

    All jurisdictions except QLD are reporting pandemic (H1N1) 2009 cases using NetEpi, a web-based outbreak case reporting system. Data from jurisdictional systems are being imported into NetEpi by VIC, NSW, WA, TAS and SA, and the remainder are entering directly into NetEpi. QLD ceased reporting into NetEpi on 6 July 2009.
    Analyses of Australian cases are based on clinical onset date, if this information is available. Where an onset date is not available, notification date has been used. Victorian cases use a calculated onset date which is the earliest available date calculated from specimen date, onset date, notification date or detection date. This assumption was made for all calculations and data on which the figures are based.

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    National Notifiable Diseases Surveillance System (NNDSS)

    NNDSS comprises of notifications from jurisdictions of laboratory-confirmed influenza cases. Laboratory confirmed influenza is notifiable in all jurisdictions in Australia. Confirmed pandemic (H1N1) 2009 cases are being received from all jurisdictions through NNDSS except for Victoria and New South Wales. NSW is also unable to send seasonal influenza notifications data.
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    Data Analysis

    Analysis of confirmed cases in conducted on combined NetEpi and NNDSS data. Analysis of morbidity (hospitalisations and ICU admissions) and mortality data is conducted on combined NetEpi and QLD hospitalisation data.
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    Laboratory Surveillance data

    Laboratory testing data are extracted from the ‘NSW Influenza Report,’ ‘The 2009 Victorian Influenza Vaccine Effectiveness Audit Report’ (VIDRL) and the ‘South Australian Seasonal Influenza Report’. These reports are provided weekly.
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    WHO Collaborating Centre for Reference & Research on Influenza (WHO CC)

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

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    Sentinel General Practice Surveillance

    The Australian Sentinel Practices Research Network (ASPREN) has Sentinel GPs who report influenza-like-illness (ILI) presentation rates in NSW, 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 2009 may be different from that of previous years. ASPREN data are sent to the Surveillance Branch on a weekly basis. Northern Territory GP surveillance data are sent to the Surveillance Branch on a weekly basis. VIDRL influenza surveillance data are sent to the Surveillance Branch on a weekly basis.

    A new testing protocol introduced through ASPREN requires GPs to test all patients presenting with an ILI on one day of the week. These data should provide a cross section of age, sex and severity of patients who seek GP assistance for ILI. This system is in the early stages of implementation and will be further developed over coming weeks.

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    Sentinel Emergency Department (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 8 Perth Emergency Departments (EDs).
    NSW - ED surveillance data are extracted from the ‘NSW Influenza Surveillance Report’. This report is provided weekly. The New South Wales Influenza Surveillance Program collects data from 49 EDs across New South Wales.
    SA – ED surveillance data are extracted from the ‘South Australian Seasonal Influenza Report’. This report is provided weekly. The South Australian Influenza Surveillance Program collects data from 4 EDs in South Australia.

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    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.

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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 season.

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    FluTracking

    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

    Footnotes

    a. Note that the while the analysis of severity is on-going, updates are only reported every four weeks unless there are significant changes detected. With the current low levels of pandemic (H1N1) 2009 activity in Australia it is anticipated that the indicators of pandemic severity will not vary significantly.


    b. As the counting of every case is no longer feasible in the PROTECT phase, influenza activity, including Influenza Like Illness (ILI) activity in the community is instead monitored by surveillance systems including: GP Sentinel ILI surveillance; Emergency Department presentations of ILI at sentinel hospitals (NSW and WA); and Absenteeism rates. Laboratory data are used to determine the proportion of pandemic (H1N1) 2009 circulating in the community


    c. Note that the while the analysis of severity is on-going, updates are only reported every four weeks unless there are significant changes detected. With the current low levels of pandemic (H1N1) 2009 activity in Australia it is anticipated that the indicators of pandemic severity will not vary significantly.


    d. When possible, information in this section is collated from reports available within the current reporting period.


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    7. References

    1. WHO pandemic (H1N1) situation update #73. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 11 November.
    2. WHO Influenza A virus resistance to oseltamivir and other antiviral medicines, 4 June 2009. Available from: http://www.who.int/csr/disease/influenza/en/ . Accessed 11 November 2009.
    3. New Zealand Public Health Surveillance, Influenza Weekly Updates. Available at: http://www.surv.esr.cri.nz/virology/influenza_weekly_update.php . Accessed 11 November 2009.
    4. WHO pandemic (H1N1) situation update #73. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 11 November 2009.
    5. CDC Influenza reports http://www.cdc.gov/h1n1flu/pubs/ . Accessed 11 November 2009.
    6. Canada Flu Watch Weekly reports, Available from: http://www.phac-aspc.gc.ca/fluwatch/09-10/index-eng.php . Accessed 11 November 2009.
    7. WHO pandemic (H1N1) situation update #73. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 11 November.
    8. Mexico Ministry of Health, portal.salud.gob.mx/contenidos/noticias/influenza/estadisticas.html , Accessed 11 November 2009.
    9. WHO pandemic (H1N1) situation update #73. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 11 November.
    10. HPA Pandemic Situational Update. Available from: http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListName/Page/1240732817665?p=1240732817665&printable=true . Accessed 11 November 2009.
    11. Influenza Surveillance in Ireland - Weekly Update. Available from: http://www.hpsc.ie/hpsc/A-Z/EmergencyPlanning/AvianPandemicInfluenza/SwineInfluenza/Surveillance%20Reports/ . Accessed 11 November 2009.
    12. WHO pandemic (H1N1) situation update #73. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 11 November.
    13. New Zealand Public Health Surveillance, Influenza Weekly Updates. Available at: http://www.surv.esr.cri.nz/virology/influenza_weekly_update.php . Accessed 11 November 2009.
    14. WHO pandemic (H1N1) situation update #73. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 11 November.
    15. World Organisation for Animal Health.http://www.oie.int/eng/press/en_091104.htm . Accessed 11 November 2009