Authorities in New South Wales (NSW), Australia have confirmed a second case of avian influenza caused by an H7N8 strain of virus in a poultry farm, presumably for egg production. within a biosecurity zone in the Hawkesbury District northwest of Syndey.  The second farm is located approximately one mile from the index case and may represent either a defect in biosecurity, infection from wild birds shedding H7N8 virus or airborne spread from the first case on entrained dust.

The press report notes that authorities required :over a week” to kill and dispose of 130,000 birds.  More resources are required to expedite depopulation and disposal to limit the spread of virus.

The outbreak of H7N8 in New South Wales is distinct from the concurrent outbreaks in the adjoining state of Victoria where seven farms have been infected with either H7N3 or H7N9 HPAI. This diversity of strains suggests a wide range of serotypes among wild birds regarded as reservoirs and disseminators of infection.

In recent years egg production in Australia has transitioned from cage housing to alternative systems including combinations of barns and outside access. The high proportion of free-range and similar management systems has created a higher level of vulnerability to infection of flocks from wild birds. It is presumed that with the current risk of infection that flocks will be confined to barns.