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Avian Influenza

A second egg farm in Victoria has tested positive for H7N7 avian influenza virus. Read Agriculture Victoria release here.

As a result of tracing investigations, two poultry farms have tested positive for an unrelated H5N2 strain low pathogenic avian influenza virus. Read Agriculture Victoria release here.

Read more about the Agriculture Victoria response, including control measures and orders, here.

You can find out more about how we respond to animal disease incursions at outbreak.gov.au.

Where there are a number of farms within close proximity to each other, it is not unusual for more than one farm to become infected when an outbreak occurs. This is particularly the case where wild birds that carry the virus, have the opportunity to mingle with production or domestic birds. However, it is unusual to see both highly pathogenic and low pathogenic strains of avian influenza occur within the same area.

About avian influenza

Avian influenza is a highly contagious viral infection, affecting mostly birds, including all species of commercially farmed poultry. Additionally, Australian native and migratory birds can carry the virus, without necessarily showing signs of being sick.

The virus spreads through contact with infected birds or contaminated materials and objects (fomites). Waterfowl are understood to be reservoirs of the virus in the wild, and the most likely source of infection for domestic flocks.

The clinical signs of AI infection are variable and influenced greatly by the virulence of the viruses involved, the species affected, age, concurrent bacterial disease and the environment.

For low pathogenicity avian influenza (LPAI), signs can include mild to severe respiratory disease, an up to 45% drop in egg production, and mortality rates of 3-15% for chickens and up to 90% in turkeys.

For high pathogenicity avian influenza (HPAI), including subtypes H5 and H7, signs can include severe respiratory disease, watery eyes, sinusitis, cyanosis of the combs, wattle and shanks, oedema of the head, ruffled feathers, diarrhoea and nervousness. Eggs laid often have no shells, and mortality is observed between 24-48 hours after the first visible signs of disease.

There have been numerous outbreaks of AI in poultry since 1976, all of which were contained and successfully eradicated. Each time, there was severe disease in affected chicken flocks and all had obvious or circumstantial evidence of contact with waterfowl.

There is little risk to human health from the H7N7 strain, as transmission to humans requires close contact with infected birds. Properly cooked eggs and meat remain perfectly safe to eat.

This is not the highly pathogenic influenza H5N1 or H1N1 strains that have gained worldwide attention — nor is it closely related to those strains. It is in no way related to the current Covid-19 pandemic.

Resources

Fact sheets

For AHA Members

For animal health professionals

For those working in the response

For producers

 

Page reviewed: 13/08/2020