Poultry producers in Europe are bracing for a bitter winter battle against Avian Influenza with cases spreading rapidly across the region. Several variants of highly pathogenic avian influenza (HPAI), commonly called bird flu, have been reported with the H5N1 and H5N8 strains seeming to be the most dominant, although at least 8 different variants are known to be in circulation. Outbreaks since the beginning of October have been reported in top EU poultry producer Poland, as well as Austria, Belgium, Croatia, Czech Republic, Denmark, France, Germany, Hungary, Ireland, the Netherlands, Scotland, Slovakia, Sweden, and the United Kingdom.
The dramatic resurgence of the disease so far this winter is definitely unwelcome news coming off a devastating 2020‐2021 bird flu season, which is calculated from October through September every year. Between October 2020 and September 2021, a total of 3,777 HPAI outbreaks affecting around 22,900,000 poultry birds were detected across 31 European countries, which is thought to be one of the largest and most devastating HPAI epidemics ever recorded in Europe.
Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus, one of four types of flu virus. A and B have the greatest impact on human health, with influenza A the type responsible for previous epidemics and pandemics. Minor changes in the surface of the virus – involving proteins called haemagglutinin (H) and neuraminidase (N) – occur between each influenza season. Influenza A viruses have 16 H subtypes and 9 N subtypes, various combinations of which result in the naming system (for example H1N1 or H5N8). Minor changes are referred to as antigenic drift and are the reason why it is necessary to reformulate the flu vaccine annually.
While HPAI typically fades during the summer, several outbreaks continued in wild birds this year, mainly in northern Europe. Wild birds normally carry AI viruses in their respiratory or intestinal tracts, but they do not usually get sick, which allows them to carry the viruses long distances. Each year in spring and summer, waterbirds mingle on their breeding grounds in Siberia and mix their influenza viruses, creating new variants they then bring to Europe, Asia, and Africa during fall migration. It’s believed migratory birds first introduced the virus to Europe in 2005. The most well-known HPAI strain, H5N1, was first isolated from a farmed goose in China in 1996.
HPAI viruses can kill up to 90-100% of a flock but disease control normally consists of culling any surviving poultry and imposing strict quarantine procedures. There are no vaccines or treatments available. These disruptions cascade beyond the farm boundary into the supply chain, with consequences ranging from those manufacturing feedstock elements for flocks, to the transport companies moving the animals.
Between December 2014 and June 2015, more than 50 million chickens and turkeys in the United States died of highly pathogenic avian influenza (HPAI) or were destroyed to stop the spread of the disease. These birds accounted for about 12% of the U.S. table-egg laying population and 8% of the estimated inventory of turkeys grown for meat. The economic impact of the 2014 outbreak have been estimated to range from $1 to $3.3 billion. (Sources: USDA ERS, WattAg, GAO)