This flu is a contagious respiratory illness caused by influenza viruses. These viruses infect the nose, throat, and sometimes the lungs. Disease severity ranges from mild to severe illness and can cause death. The flu infects many different species including humans, pigs, horses, dogs, marine mammals, and birds, including wild birds and domestic poultry (Centers for Disease Control and Prevention 2017). There are four types of flu: Influenza A, B, C, and D (World Health Organization n.d.). Flu viruses are categorized into subtypes by two of their proteins: hemagglutinin (H) and neuraminidase (N). There are currently 18 H types and 11 N types of flu viruses.
It is important to note that aquatic birds, such as ducks and geese, are the primary natural reservoir for most influenza A viruses. As hosts, they spread the influenza A virus worldwide during their natural migrations, which prevents eradication of the virus. Four of these bird migration pathways cross the United States, including major poultry producing areas.
When the Highly Pathogenic Avian virus infection is found in poultry (H5 or H7 viruses) it can affects multiple internal organs resulting in a mortality rate of up to 100%, often within 48 hours. When H5 or H7 avian influenza outbreaks occur in poultry, infected flocks are typically depopulated or culled. The preferred method of stopping spread is to quarantine and screen flocks that are near or linked to the infected flock. If the virus is detected, these flocks are depopulated to stop further spread.
The 1983–84 HPAI H5N2 outbreak resulted in humanely euthanizing approximately 17 million chickens, turkeys, and guinea fowl in Pennsylvania and Virginia to contain and eradicate the disease. In 2015, HPAI A(H5N2) was associated with a large domestic poultry outbreak in North America that affected over 49 million domestic birds. In late December 2021, H5N1 was detected in eastern Canada at an exhibition farm resulting in significant mortality prior to the remaining flock being euthanized (McCarthy 2021). On January 14, 2022, the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed highly pathogenic Eurasian H5 avian influenza (HPAI) in a wild American wigeon in Colleton County, South Carolina. HPAI has since been detected in several other wild birds in the Carolinas, Virginia, Florida, and Maryland. Up to date detections can be found on the USDA APHIS website at aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/2022-hpai.
Source: Scott P. Kenney, PhD, Assistant Professor, OARDC, Ohio State University Extension, Wooster
For additional details: https://ohioline.osu.edu/factsheet/vme-1037