The state of Iowa announced this week that it would have to put more than 4 million chickens to death after discovering a case of the highly virulent avian flu at a large egg farm.

Crews are currently slaughtering 4.2 million chickens after discovering the disease at a farm in Sioux County, Iowa. This long-running outbreak is the latest to affect dairy cattle. An egg farm west of Minneapolis, Minnesota, confirmed the virus last week, resulting in the slaughter of around 1.4 million chickens.

According to the U.S. Dept. of Agriculture, since the outbreak began in 2022, 92.34 million birds have perished.

Although bird flu has become quite widespread among poultry, concerns about the disease have increased as a result of its spread to cattle. In May, researchers identified avian flu in a second dairy farmworker and detected the virus in milk and beef. Farms raising dairy cattle in nine states have proven their existence.

According to agriculture and health professionals, there is still little risk to the general public. The U.S. Department of Agriculture maintains the safety of beef, prohibiting the entry of meat from a single unwell dairy cow into the country’s food chain.

Employees who handle contaminated animals are more vulnerable. Two dairy workers and a man who worked on a poultry farm, killing sick birds, were among the three confirmed human cases in the United States.