In 2015, an outbreak of avian influenza subtype H5N2 was identified in a series of chicken and turkey farming operations in the Midwestern United States. By May 30, more than 43 million birds in 15 states had been destroyed as a result of the outbreak, including nearly 30 million in Iowa alone, the nation's largest egg producer. In the Midwestern U.S., the average price of eggs had increased 120% between April 22 and May 30. The effects however were seen nationwide, with prices in California up 71% in the same timeframe.
The virus was first identified in Minnesota in early March. Prior to April 20, it affected commercial turkey farms almost exclusively, in the states of Arkansas, Iowa, Missouri, North Dakota, South Dakota, Wisconsin, and at 28 farms in Minnesota, where the virus was initially identified. Migratory waterfowl are assumed to have brought the disease to the Midwest, but how it made its way into poultry barns is undetermined.
Spread to hen farms
On Monday, April 20, the U.S. Department of Agriculture announced that 5.3 million egg-producing hens at a northwest Iowa farm must be destroyed after the virus was confirmed. The number at this operation alone comprised a little over 1% of egg-laying hens in the United States.
As of May 27, over 25 million chickens had either died of the infection or been euthanized in Iowa alone. Nebraska's toll at the same date was 7 million—a majority of the state's 9.45 million egg-laying hens.
Table of infections
This table shows large bird farm infections during the 2015 outbreak. All birds affected either died of the H5N2 infection itself, or were destroyed as a precautionary measure. While 205 total infections were confirmed through June 1, only larger outbreaks (affecting >200,000 hens or >50,000 turkeys) are displayed here.
Date detectedLocationBirds affectedTypeSourceMarch 27Lac qui Parle County, Minnesota66,000TurkeysApril 1Beadle County, South Dakota50,600TurkeysApril 2Stearns County, Minnesota71,000TurkeysApril 4Stearns County, Minnesota76,000TurkeysApril 7Meeker County, Minnesota310,000TurkeysApril 8Kingsbury County, South Dakota71,900TurkeysApril 9Lyon County, Minnesota66,000TurkeysApril 10McPherson County, South Dakota55,200TurkeysApril 10McCook County, South Dakota54,700TurkeysApril 11Jefferson County, Wisconsin189,100ChickensApril 13Swift County, Minnesota160,000TurkeysApril 13Stearns County, Minnesota76,000TurkeysApril 14Swift County, Minnesota154,000TurkeysApril 14Redwood County, Minnesota56,000TurkeysApril 15Kandiyohi County, Minnesota152,000TurkeysApril 15Stearns County, Minnesota67,000TurkeysApril 15Roberts County, South Dakota66,600TurkeysApril 16Barron County, Wisconsin126,700TurkeysApril 20Osceola County, Iowa3,800,000ChickensApril 20Wadena County, Minnesota301,000TurkeysApril 20Kandiyohi County, Minnesota61,000TurkeysApril 21Kandiyohi County, Minnesota130,400TurkeysApril 21Kandiyohi County, Minnesota61,000TurkeysApril 21Stearns County, Minnesota53,900TurkeysApril 22Stearns County, Minnesota72,500TurkeysApril 22Kandiyohi County, Minnesota62,600TurkeysApril 22Kandiyohi County, Minnesota62,600TurkeysApril 22Meeker County, Minnesota58,900TurkeysApril 23Clay County, Minnesota408,500ChickensApril 23Chippewa County, Wisconsin56,500TurkeysApril 23Kandiyohi County, Minnesota54,300TurkeysApril 24Jefferson County, Wisconsin1,031,000ChickensApril 24LaMoure County, North Dakota71,500Mixed poultryApril 24Kandiyohi County, Minnesota67,000TurkeysApril 24Chippewa County, Minnesota64,900TurkeysApril 27Sioux County, Iowa1,603,900ChickensApril 27Barron County, Wisconsin83,300TurkeysApril 28Sioux County, Iowa3,660,000ChickensApril 28Osceola County, Iowa258,000ChickensApril 28Steele County, Minnesota82,900TurkeysApril 28Kandiyohi County, Minnesota50,900TurkeysApril 29Stearns County, Minnesota202,500ChickensApril 30Buena Vista County, Iowa449,100TurkeysApril 30Barron County, Minnesota96,500TurkeysMay 1Buena Vista County, Iowa4,910,600ChickensMay 4Madison County, Iowa1,495,600ChickensMay 5Wright County, Iowa2,821,800ChickensMay 5Nicollet County, Minnesota1,102,900ChickensMay 5Barron County, Wisconsin182,400TurkeysMay 5Swift County, Minnesota151,300TurkeysMay 5Kandiyohi County, Minnesota89,100TurkeysMay 5Pipestone County, Minnesota72,200TurkeysMay 5Barron County, Wisconsin57,200TurkeysMay 6Kandiyohi County, Minnesota65,000TurkeysMay 7Sioux County, Iowa309,900ChickensMay 7Osceola County, Iowa256,000ChickensMay 7Buena Vista County, Iowa52,900TurkeysMay 8Wright County, Iowa1,106,500ChickensMay 8Sioux County, Iowa581,300ChickensMay 8Sioux County, Iowa327,900ChickensMay 8Sioux County, Iowa303,100ChickensMay 11Swift County, Minnesota65,600TurkeysMay 12Dixon County, Nebraska1,791,500ChickensMay 12Wright County, Iowa966,600ChickensMay 13Hutchinson County, South Dakota70,600TurkeysMay 13Yankton County, South Dakota70,600TurkeysMay 14Lyon County, Iowa390,000ChickensMay 15Dixon County, Nebraska1,709,400ChickensMay 15Buena Vista County, Iowa903,700ChickensMay 15Sioux County, Iowa272,300ChickensMay 15Sioux County, Iowa240,000ChickensMay 18Moody County, South Dakota642,700ChickensMay 18Meeker County, Minnesota138,800TurkeysMay 19Renville County, Minnesota2,045,600ChickensMay 20Sioux County, Iowa240,000ChickensMay 21Sac County, Iowa100,000TurkeysMay 26Dixon County, Nebraska293,200ChickensMay 27Knox County, Nebraska3,000,000 ChickensMay 27Adair County, Iowa974,500ChickensMay 27Renville County, Minnesota95,300TurkeysMay 28Wright County, Iowa991,500ChickensMay 28Kandiyohi County, Minnesota50,800TurkeysJune 1Wright County, Iowa434,800ChickensJune 1Moody County, South Dakota52,000Turkeys
Control
When an infection was confirmed, all birds at the affected farm were destroyed per USDA guidelines. The birds were often culled by foam depopulation through pumping an expanding water-based foam into the barn houses, which suffocates them within minutes. The birds were then composted, usually at the location.
References