Avian influenza: The signs and symptoms

Avian influenza (AI) has been spreading across Europe in recent years, with the most recent case in the UK occurring in December 2019 on a Suffolk broiler breeder unit, where there was an outbreak of the H5 strain.

During the bird migration season, which peaks between December and January, free-range poultry keepers are advised to move stock indoors, or at least keep them separated from wild birds, as a precaution against AI.

It is important to be aware of the signs and symptoms of avian flu as well as the biosecurity measures recommended so that you can reduce the risk of infection and spread.

How to spot AI

There are two types of AI – high pathogenic and low pathogenic.

High-pathogenic AI (HPAI)

HPAI is the more serious type. It is often fatal in birds. The main clinical signs are:

  • Swollen head
  • Blue discolouration of neck and throat
  • Loss of appetite
  • Respiratory distress such as gaping beak, coughing, sneezing, gurgling, rattling
  • Diarrhoea
  • Fewer eggs laid
  • Increased mortality
  • Clinical signs can vary between species and some may show minimal clinical signs (ducks and geese).

Low-pathogenic AI (LPAI)

  • LPAI is usually less serious
  • It can cause mild breathing problems, but affected birds will not always show clear signs of infection
  • The severity of LPAI depends on the type of bird and whether it has any other illnesses.

Biosecurity measures

  • The government chief vet advises enhanced biosecurity in light of the risk of infection, including:
  • Cleaning and disinfecting clothing, footwear, equipment and vehicles before and after contact with poultry
  • Reducing the movement of people, vehicles or equipment to and from areas where poultry are kept to minimise contamination from manure, slurry and other products
  • Thoroughly cleaning and disinfecting housing at the end of a production cycle
  • Keeping fresh disinfectant at the right concentration at all points where people should use it, such as farm entrances and before entering poultry housing
  • Minimising direct and indirect contact between poultry and wild birds, including making sure all feed and water is not accessible to wild birds

For more information, see the government guidance on avian flu