How is Australia impacted by the recent increase in Detections of Avian Influenza in the Northern Hemisphere? - 24 february 2021
Avian influenza virus (AIV) infection can cause severe disease in poultry and can also infect and cause disease in a range of other species including wild birds and humans. There are two categories of AIVs: low pathogenicity and high pathogenicity.
The main natural reservoirs for low pathogenicity strains of AIV are wild waterfowl and to a lesser extent, shorebirds, with infection typically resulting in only mild or no clinical signs of disease in these birds. Whilst a rare occurrence, low pathogenicity strains of AIV can spill over from wild bird populations into poultry where they can then mutate into high pathogenicity viruses leading to severe disease and high mortality.
Data generated by the National Avian Influenza Wild Bird Surveillance (NAIWB) program, which screens samples from wild birds for AIVs, is used to monitor and understand avian influenza in wild birds in Australia. Over the life of the 17-year program, thousands of wild bird samples have been screened with no high pathogenicity AIVs found in our wild birds.
The high pathogenicity avian influenza virus strains (goose/Guandong HPAI H5Nx virus clade 18.104.22.168) currently circulating in the northern hemisphere originally emerged in 2014 and has spread with wild birds from Asia to Europe, Africa, and North America.
Unlike other strains, these virus strains have been detected in apparently healthy wild birds, likely facilitating their rapid intercontinental spread through bird migration.
To date, Australia remains free from these strains of viruses currently being detected in the northern hemisphere. Studies to date have found no evidence that migratory birds are carrying infectious high pathogenicity viruses when they arrive in Australia. Analysis of recent outbreaks of AIV in poultry in Victoria were found to be strains closely related to those circulating in Australian wild birds, and not imported avian influenza virus strains from Asia or elsewhere.
However, the current widespread and frequent detection of high pathogenicity AIVs in the northern hemisphere, notably Europe and Asia, likely means an increased level of risk to Australia, though previous research has assessed the overall risk of introduction of high pathogenicity AIVs to Australia to be low.
Increased awareness and vigilance by Australian poultry producers and wildlife health professionals is advised. There is a need to remain vigilant by:
- maintaining best biosecurity practices by poultry producers and wildlife professionals
- investigating unusual and mass bird (domestic and wild bird) sickness and/or deaths
- reporting any such events: https://www.outbreak.gov.au/report-outbreak
- continuing monitor AIV strains circulating in apparently healthy Australian wild birds for overseas strains through the NAIWB program.
- reporting any unusual signs of disease or deaths in wildlife to: Your State/Territory Wildlife Health Australia (WHA) Coordinator, or the 24-hour Emergency Animal Disease Watch Hotline on freecall 1800 675 888.
Further technical information: