Virus WAtch Week Ending 5 July 2015

Influenza and Influenza-like Illnesses (ILI)

Summary: ILI activity and more direct indicators of influenza virus activity all increased this week, indicating influenza season has commenced.

• ILI presentations to sentinel emergency departments (EDs) and sentinel general practitioners (GPs) increased this week.
• Hospitalisations with confirmed influenza have been relatively steady over recent weeks, at around 10 per 1000 admissions.
• Influenza virus detections, notifications and test positivity rate in both sentinel and routinely collected specimens all increased this week ; influenza B viruses (80%) and influenza A/H3N2 (19%) viruses remain the dominantly detected subtypes, with very little influenza A/H1N1 circulating. The influenza B strains currently circulating are around 90% Yamagata lineage, matching the trivalent influenza vaccine strain.
• Overall non-influenza respiratory virus detections increased, and respiratory syncytial virus activity remains particularly high.

Gastroenteritis

• Gastroenteritis presentations to sentinel GPs and EDs are relatively steady and consistent with levels experienced previously at this time of the year.
• Rotavirus detections increased and remain high. Rotavirus has caused recent outbreaks of gastroenteritis in residential care and childcare settings in metropolitan Perth.

Varicella and Viral Rashes

• Chickenpox and shingles presentations to sentinel EDs and GPs are near or below baseline levels.
• No cases of measles or rubella were notified.
• Several further cases of mumps have been confirmed among Aboriginal children, teenagers and young adults in the Kimberley region, including in Broome.

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