Virus WAtch Week Ending 30 August 2015

Influenza and Influenza-like Illnesses (ILI)

Summary: Indicators of influenza activity remained stable or declined this week, further indicating we may have reached the peak of the influenza season. Non-influenza respiratory virus activity continues to decline.

• ILI presentations to sentinel general practitioners (GPs) and emergency departments (EDs) remain relatively stable and within ranges seen in recent mild influenza seasons.
• Influenza virus detections, notifications and percent positivity decreased this week. Influenza B virus (62% of detections) continues to predominate, and a majority of detected B strains are Yamagata lineage (consistent with the trivalent vaccine); influenza A/H3N2 comprised 33% of subtyped cases this week.
• Hospitalisations with confirmed influenza remain stable and below the average observed at this time in recent seasons.
• Respiratory syncytial virus and other non-influenza respiratory virus activity continue to decline.

Gastroenteritis

• Gastroenteritis presentations to sentinel GPs and EDs remain low.
• Rotavirus detections decreased this week and norovirus activity remains low and relatively stable.

Varicella and Viral Rashes

• Shingles and chickenpox presentations to sentinel EDs and GPs are near or below baseline levels.
• No cases of measles were confirmed.
• One locally-acquired rubella case was notified in an unvaccinated contact of a case infected in Indonesia.
• Further cases of mumps have been confirmed in the Kimberley and Pilbara regions, primarily among Aboriginal children, teenagers and young adults. Most recent cases are residents of Broome or Port Hedland, or nearby communities.