HPAI H7 outbreaks in Australia in 2024

In 2024, Australia experienced three concurrent outbreaks of high pathogenicity avian influenza (HPAI) involving eleven commercial poultry farms and five residential premises. • HPAI H7N3 was detected on seven farms in Victoria. • HPAI H7N9 was detected on one farm in Victoria. • HPAI H7N8 was detected on two farms in New South Wales and one farm in the Australian Capital Territory. Immediately following the first detection of HPAI on 22 May 2024 an emergency animal disease response was commenced and managed in accordance with Australia’s nationally agreed policies. This response was based on the Australian Veterinary Emergency Plan response strategy for avian influenza (AUSVETPLAN). Control measures were coordinated through the national Consultative Committee on Emergency Animal Diseases and implemented by the relevant jurisdictions. A rapid and effective ‘stamping out’ program was carried out, with depopulation and disposal, followed by decontamination. Vaccination was not used in the response, and Australia is currently progressing towards a return to country-level freedom from HPAI. The first detection of each subtype was made on premises that were mixed free-range and cage egg-layer chicken farms. Other farm types infected included: barn-housed chicken egg-laying, free-range broilers, a pullet rearing facility and a barn-housed duck egg and meat farm. Molecular epidemiological analysis indicated that the emergence of each subtype (H7N3, H7N9 and H7N8) was due to separate spillover events of low pathogenicity avian influenza viruses from Australian wild birds into commercial poultry, with subsequent mutation to HPAI viruses.

Andrew Breed, Australian Government, Department of Agriculture Fisheries and Forestry Emily Doyle, NSW Government, Department of Primary Industries and Regional Development Kyeelee Driver, ACT Government, Environment, Planning and Sustainable Development Directorate Paul Eden, Wildlife Health Australia Emily Glass, Australian Government, Department of Agriculture Fisheries and Forestry Sally Salmon, Victorian Government, Department of Environment and Primary Industries Frank Wong, CSIRO, Australian Centre for Disease Preparedness

Notable outbreaks, field and molecular epidemiology, and surveillance in poultry