The nature of wild bird species and their behaviors should drive the poultry industry’s understanding of highly pathogenic avian influenza (HPAI) viruses, a subtype of influenza A viruses, in wild bird populations, according to University of Minnesota Department of Veterinary and Biomedical Sciences Professor Dr. Carol Cardona.
“Migration is a critical avian behavior for influenza ecology,” she stated during the Council for Agricultural Science and Technology’s (CAST) webinar titled “HPAI and Its Impact on Food Production Industries.”
During migration, groups of birds are constructed, deconstructed and reconstructed, Cardona explained. Birds come together into groups for breeding before migrations begins. If the virus exists in one of those birds, multiple will have it after the breeding period is over.
“Each of those groups come together and bring their own influenza to a new ecosystem, which is how those viruses begin to mix and be shared.”
Additionally, new viruses can be created when one host is infected with more than one type of the virus. New influenza viruses tend to fall apart, especially in reservoir hosts, organisms that contract a pathogen and suffer no illness, where multiple viral subtypes are coming together, she explained.
Species and their habitats
According to Cardona, the industry should remember multiple species of birds and mammals that can host influenza A viruses are stationary and do not migrate.
“This creates a dynamic and an ecology of mixed genetics moving from north to south or south to north over resident animals,” Cardona stated.
Habitats that are linked to water usually contain better reservoir hosts for the virus. For example, mallards, who reside in an aquatic habitat, are likely to have more diverse avian influenza viruses compared to wood ducks, who mainly nest in trees.
Pathogenicity and virulence vary by species, which influences how birds react to influenza viruses. For instance, a mallard may show few or no clinical signs when infected with the same virus that can cause death in white leghorn birds.
“Although we often perceive birds as a singular, they should be viewed as multiples. Their collective biology shapes the ecology of future viruses,” Cardona said.