ABSTRACT
Between December 2014 and June 2015, an outbreak of H5N2 HPAI caused the largest and most expensive agriculture emergency in U.S. Department of Agriculture-Animal and Plant Health Inspection Service history. The outbreak affected 21 states; 232 poultry farms (211 commercial and 21 backyard) were affected, and approximately 49.6 million birds were depopulated on poultry farms. The majority of affected farms were commercial turkey operations (n = 160). This report is a case series describing 104 H5N2 HPAI-affected turkey farms in Iowa, Minnesota, Missouri, North Dakota, South Dakota, and Wisconsin that had H5N2 HPAI virus detected between March 5 and June 1, 2015. The farm manager or farm personnel voluntarily completed an epidemiologic questionnaire administered by state and federal animal health officials. Equipment and vehicle sharing with other farms was common, particularly for feed trucks (77% of farms shared feed trucks with other farms), live haul loaders (90.4%), poult trailers (72.0%), and preloaders (80.7%). Many farms had water bodies in proximity to the farm, such as a pond (42.6%) or stream (21.8%). About one-third of farms (33.7%) reported seeing wild birds inside the turkey barns. Only 44.2% of farms reported that third-party biosecurity audits or assessments had been conducted. Because the newly introduced Asian H5N8 HPAI and two new HPAI viruses, H5N2 and H5N1, are now circulating in U.S. wild birds, primarily migratory waterfowl, a greater potential for reoccurrence exists with the spring and fall migratory seasons, representing higher risk periods for outbreaks of HPAI in commercial poultry farms in the future. Eliminating exposure to wild birds, especially waterfowl or environments contaminated by wild waterfowl, will reduce risk of reintroduction of H5N2 HPAI virus, and ensuring good on-farm biosecurity will help the poultry industry avoid introduction of influenza and lateral spread between farms.
