s of February, the 2022-23 outbreak of highly pathogenic avian influenza (HPAI) had affected 770 poultry flocks and led to the “depopulation” (mass killing and disposal) of 59 million farmed birds in the United States alone. One of the primary depopulation methods has been “ventilation shutdown plus” (VSD+), which involves turning off the airflow in a barn and turning up the temperature, in effect killing the animals by heat stroke. The increasing use of VSD+ has created an ethical controversy within the US veterinary community, as described in a recently published paper in the journal Animals co-authored by AWI veterinary consultant Dr. Gwendy Reyes-Illg.
Industrial farms confine tens or hundreds of thousands of genetically similar birds in a single building, often in unhygienic and highly stressful settings. Such conditions—in addition to encouraging inhumane depopulation methods—provide the perfect breeding ground for viruses such as HPAI.
In addition to the outbreak in commercial and backyard poultry, HPAI has been detected in more than 6,000 individual wild birds, as well as several mammal species in the United States, including gray and harbor seals, bobcats, brown and black bears, skunks, red foxes, raccoons, and opossums. Detection in mammals has increased concern among scientists that the virus could mutate into a strain that is more easily transmitted to humans, leading governments around the world to reconsider once-shunned vaccines as a means of reducing spread of the disease.