The 2014-15 outbreak is considered the most destructive in the country’s history. It caused poultry and egg prices to soar and cost the industry more than $3 billion — even though the federal government was compensating farmers for lost flocks. Ultimately, nearly 50 million birds were killed or destroyed by the virus to prevent its spread, the vast majority of them in Iowa and Minnesota.
John Burkel, 54, a fourth-generation turkey farmer in northern Minnesota, has watched the spread with trepidation. In 2015, the virus swept through his farm in a matter of days, leaving just 70 survivors in a barn containing 7,000 birds. The weeks that followed were spent clearing out, composting the dead and repeatedly disinfecting the barns.
As a precaution, health officials also advised that he and his son take a course of the antiviral drug Tamiflu. “We’ve never seen such a virulent virus,” said Mr. Burkel, a state legislator who works on the farm with his wife and two children. “It was just awful.”
Since then, agricultural officials across the country have urged farmers to take a series of biosecurity measures to prevent outbreaks. These include sealing small holes through which mice or sparrows can enter barns, disinfecting the tires of feed delivery trucks before entering a farm, and creating “clean” and “dirty” zones where workers have fresh shoes and put on overalls before walking. in an animal shelter.
At the same time, experts say federal officials have strengthened the national surveillance system that allows researchers to track the spread of avian flu in wild bird populations in near real time. “I think the 2015 crisis made us realize that it takes a village to prevent an outbreak and prepared us much better,” said Dr. Yuko Sato, a poultry veterinarian at Iowa State University, who advises local farmers on how to improve their biosafety practices.
But hypervigilance has its limits, especially against a microscopic pathogen that can infiltrate a sty on the leg of a single housefly. For a growing number of scientists, the real threat is the country’s industrialized system of meat and dairy production, with its reliance on genetically identical creatures packed by the thousands in huge confinement barns.
Nearly all of the nine billion chickens raised and slaughtered in the United States each year can trace their lineage to a handful of breeds engineered to promote rapid growth and plump breasts. The birds are also exceptionally vulnerable to disease outbreaks. “They all have the same immune system, or lack of immune system, so once a virus gets into a shed, it will spread like wildfire,” says Dr. Hansen, the public health veterinarian.
