What is the risk of farmed poultry contracting avian influenza (or ‘bird flu’)?

Avian influenza, commonly called bird flu, is a highly contagious viral disease that primarily affects birds but can also pose risks to other animals and humans [1]. The virus is spread by shorebirds and wild waterfowl such as ducks, geese, and swans, because they serve as natural reservoirs of the virus. These birds can carry the virus without showing any signs of disease and their migratory nature exposes Australian farmed poultry to potential avian influenza outbreaks. Implementation of good biosecurity practices can help reduce the risk of disease outbreaks.

What is avian influenza?

Avian influenza is found globally, affecting all continents, including Antarctica. It is known to affect more than 140 bird species including farmed poultry such as chickens, turkeys, quail, guinea fowl, ducks, geese, emus and ostriches [2]. Strains of the virus can be classified as low pathogenic (causing mild or no symptoms) or highly pathogenic (leading to severe disease and high mortality rates in birds). In the event of an avian influenza outbreak (e.g. caused by farmed poultry being exposed to virus-carrying wild birds), large numbers of poultry may require euthanasia to prevent further spread of the virus. Read more about avian influenza, its impact on animal welfare and what happens in the event of an outbreak in Australia.

What influences the risk of poultry contracting avian influenza?

In Australia, indoor and free-range poultry, are at risk of contracting avian influenza due direct and indirect contact with waterfowl who may carry avian influenza virus in their nasal and eye discharge or faeces, farming and biosecurity practices.

Indoor (barn or shed) systems limit poultry from direct exposure to wild birds, but these are not immune to avian influenza risks due to indirect contact. This is because equipment, vehicles and human movements between farms can introduce the virus indoors, in particular when on-farm dams or open water sources act as a permanent residence for waterfowl.

Birds with outdoor access (free range) are at risk of coming into direct or indirect contact with wild waterfowl. Vegetated range areas may attract waterfowl, in particular if poultry are given feed or water outdoors. In free-range production systems, producers should therefore focus on managing these systems to reduce the risk of avian influenza.

In the event of an avian influenza outbreak, government-imposed quarantine and movement restrictions may apply to properties and poultry nearby. For free-range poultry within the quarantine radius, housing orders may require free-range poultry to be temporarily kept indoors to mitigate their risk of exposure to the virus.

How can the risk of avian influenza be managed in indoor and free-range poultry farms?

The risk of farmed poultry contracting avian influenza can be mitigated through robust biosecurity practices [3,4] including (but not limited to):

• Farm location: adequate placement in areas with few waterfowl, avoiding known wild bird flight paths, and having a low concentration of poultry farms helps limit disease spread.
• Equipment and vehicle disinfection: sharing equipment and vehicles between poultry farms is known to spread of the virus between farms [3], particularly where little or no disinfection of equipment occurs. Human movement between farms is also a known risk factor. Records like visitor logs, equipment and vehicle movements, as well as hand and boot washing facilities between sheds can limit disease spread.
• Wild waterfowl and outdoor access: deterring waterfowl from poultry farms can greatly reduce the risk (e.g. ensuring that free range poultry are given feed and water inside the shed, rather than on the range). Poultry sheds and range areas should be as far away as possible from open water sources to help reduce the risk of waterfowl contact.
• Water treatment: farms that source drinking water for poultry from open water sources can reduce their risk if water is treated and sanitised before use [5].
• Bird management: good bird health and welfare are critical to minimise risk of any disease, including avian influenza. Strategies include managing stocking density to avoid overcrowding, maintaining litter quality in a dry and friable condition, preventative vaccine protocols and parasite management, and actively monitoring birds for early signs of disease.

Comprehensive biosecurity measures are essential across all production systems. Education on good biosecurity practices and their effective implementation are critical to minimise the risk of disease outbreaks.