Current Report Summary
- Although overall influenza activity remains relatively low, the steady national increase has continued.
- Since the beginning of the year there have been 7,827 laboratory confirmed cases of influenza reported. Over the past fortnight there were 1,436 notifications, with almost a third reported from New South Wales (508).
- Nationally, whilst influenza A remains the predominant influenza virus type, the proportion of influenza B notifications decreased slightly this fortnight. During the 2012 season there were very few notifications of influenza A(H1N1) pdm09. So far in 2013 whilst the majority of influenza A reports are unsubtyped, more than 10% of overall notifications have been reported as influenza A(H1N1) pdm09.
- Across jurisdictions the distribution of influenza types and subtypes is variable. In Victoria there is a predominance of influenza type B, whereas most other states are reporting a predominance of influenza type A, with NSW reporting mostly A(H1N1)pdm09 and Western Australia mostly A(H3N2).
- Over the past few weeks there has been a continued seasonal increase in influenza associated hospitalisations. Around 10% of influenza cases have been admitted directly to ICU. The age distribution of hospital admissions shows peaks in the 0-9 and over 60 years age groups.
- The WHO has reported that influenza activity in the northern hemisphere temperate zones remains at inter-seasonal levels. In the temperate countries of South America and Southern Africa, influenza transmission peaked in late June and was primarily associated with influenza A(H1N1)pdm09.
- The WHO has reported on an additional laboratory-confirmed case of human infection with avian influenza A(H7N9) virus in China. This is the second new confirmed case since 29 May 2013. There continues to be no evidence of sustainable human-to-human transmission. A recent serology study on members of the general public and poultry workers found evidence which supports suspicions that poultry are the source of the outbreak and mild or asymptomatic cases are more common than initially thought.
- The United States has reported further cases of the influenza A(H3N2) variant virus that were associated with fair attendance and contact with swine. The virus detected is the same as the variant viruses detected during the 2012 multi-state outbreak, which was also associated with swine exposure at agricultural fairs.
- Australian Influenza Surveillance Report No.04, 2013 (PDF 1474 KB)
- Australian Influenza Surveillance Report No.04, 2013 (Word 1665 KB)
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