Attention! This is a potentially life-threatening condition for your bird and possibly your flock. Time is of the essence, contact your veterinarian immediately.Find me a Vet

Avian Influenza

Fowl Pest, Fowl Plague

Highly pathogenic avian influenza (HPAI), initially known as 'fowl plague' is a complex infection of birds caused by viruses of the Influenza A genus. HPAI in poultry is characterized by a sudden onset, severe illness of a short duration, and a mortality approaching virtually 100% in vulnerable species. Due to excessive economical losses to the poultry industry, HPAI receives immense attention in the veterinary world and is globally treated as a disease immediately notifiable on suspicion to the authorities. Because of their potential to give rise to HPAIV, LPAI caused by subtypes H5 and H7 is also considered notifiable.

Recently, however, avian influenza acquired worldwide attention when a highly pathogenic strain of the subtype H5N1, which probably arose before 1997 in Southern China, gained enzootic status in poultry throughout South East Asia and unexpectedly 'traversed interclass barriers' when transmitted from birds to mammals (cats, swine, humans).

Wild aquatic birds, notably members of the orders Anseriformes (ducks and geese) and Charadriiformes (gulls and shorebirds), are carriers of the full variety of influenza virus A subtypes, and thus, most probably constitute the natural reservoir of all influenza A viruses. While all bird species are thought to be susceptible, some domestic poultry species - chickens, turkey, guinea fowl, quail and pheasants - are known to be especially vulnerable to the sequelae of infection.

Incubation Period
Following an incubation period of usually a few days (but rarely longer than 21 days).


Sneezing and/or coughing
Decreased egg production
Slight facial swelling
Difficulty breathing
Sudden death
Purple discoloration of wattles, combs, and legs
Nasal discharge


  • History
  • Clinical signs
  • Virus isolation
  • HA, HI
  • dot-ELISA
  • PCR
  • Immunohistochemistry
  • Necropsy


MethodMethod Summary
Report diseaseAI is a reportable disease in the United States, meaning that if you suspect that your duck has this disease, by law you need to report it to your veterinarian, or a state or federal veterinarian.
In mild cases, good husbandry, proper nutrition and broad spectrum antibiotics may assist in recovery.


  • Keep feed under cover to minimize attracting wild birds
  • Keep water fresh and free of droppings
  • Control vermin
  • Keep ducks and chickens separate.



Risk Factors

  • Poor biosecurity
  • High population of wild birds, particularly waterfowl

Also Consider