Avian influenza is a highly contagious viral disease caused by influenza A viruses. Viruses are divided into different subtypes. In birds, the virus infection can occur in two forms - as highly pathogenic or as low pathogenic avian influenza.
Highly pathogenic avian influenza is characterized by high morbidity and mortality. In low pathogenic aviar influenza, mild clinical signs and low mortality occur, but the disease may go unnoticed. All poultry, pigeons, runners, and ornamental and wild birds are susceptible to AI infection.
Infection in poultry most often occurs through contact with infected waterbirds or through contact with contaminated surfaces. The first clinical signs may appear within a few hours to 14 days after infection. The clinical signs are very different, the respiratory, digestive, reproductive or nervous systems may be affected. The most obvious sign is high mortality, even up to 100%, which can occur without previous clinical signs.
The most characteristic signs of the disease are: indifference, reduced consumption of feed and water, ruffled feathers, reduced or unusual advertising, sneezing, coughing and discharge from the nostrils and subcutaneous edema. A strong drop in laying capacity is observed. The faeces are liquid and green or white in color. The skin on the head and legs is cyanotic. Nervous disorders also occur (shaking and twisting of the head and neck, convulsions, uncoordinated movement, animals have difficulty standing, are inactive, have drooping wings).
Poultry keepers, farmers, other workers, transporters and means of transport transporting poultry or feed to or from the farm are the most common causes of the spread of the disease. Poultry keepers must pay attention to the appearance of clinical signs of disease in poultry and consistently implement preventive and biosecurity measures.
Biosecurity measures are:
- Prevention of access of wild birds (especially waterbirds) to poultry - accommodation of poultry in closed facilities or in covered enclosures,
- preventing wild birds from accessing feed and water for poultry,
- open-air water catchments, in those species of poultry where necessary for animal welfare purposes, shall be used in such a way as to prevent access to wild waterbirds,
- restrictions on visits by people to poultry housing or compliance with measures to prevent the spread of disease (installation of disinfection barriers, use of protective clothing and footwear, washing and disinfection of hands),
- use of disposable equipment or cleaning and disinfection of equipment before use on another poultry holding,
- poultry keepers who use releases for their animals in breeding technology shall limit the daily release to the shortest possible time.
Avian influenza is a particularly dangerous animal disease and is a mandatory notifiable disease. Any suspicion or occurrence of the disease must be reported immediately to the nearest veterinary organization or the regional office of the Administration for Food Safety, Veterinary Sector and Plant Protection.