Infectious Diseases 2021

Infectious Diseases 2021

An outbreak of HPAI H7N7 in Australia - 2020

Microorganisms 2021, 9, 1639 27 August, 2021

In 2020, between 31 July and 25 August, several geographically isolated farms in Victoria, Australia, experienced an outbreak of highly pathogenic avian influenza (HPAI) virus H7N7 and low pathogenic avian influenza (LPAI) viruses H5N2 and H7N6. The Victorian outbreak also detected LPAI H7N6 in emus at a commercial farm. OIE reports indicate more than 433,000 birds were destroyed as a control measure.

 Avian Influenza Virus Detected in Location (Farm Numbers) Date of Last Reported Occurrence
H7N7 (HPAI) Chicken Lethbridge, Victoria (3) 21 February 2014
H5N2 (LPAI) Turkey
Lethbridge, Victoria (1)
Bairnsdale, Victoria (1)
Lethbridge, Victoria (1)
Bairnsdale, Victoria (1)
26 June 2013
H7N6 (LPAI) Emu Kerang, Victoria (1) 2007

 

Novel influenza A viruses can emerge by mixing different viral strains in a host susceptible to avian and human influenza strains. Studies show that emus are susceptible to infections from a wide range of influenza viral subtypes, including H5N1 and the pandemic H1N1. The emu’s internal organs and tissues express abundant cell surface sialic acid receptors that favour the attachment of avian and human influenza viruses, increasing the potential for internal genetic reassortment and the emergence of novel influenza A viruses. A new review summarises the historical context of H7N7 in Australia, considers the potential for increased virulence and pathogenesis through mutations and draws attention to the emu as potentially an unrecognised viral mixing vessel.