OKLAHOMA CITY - The Oklahoma State Department of Agriculture is warning people to be aware of bird flu.

For big producers that means keeping birds indoors and making sure anyone who enters the space is virus-free. It's an even higher risk for free-range chickens.

The U.S. Department of Agriculture says avian influenza has made the jump to at least one domestic flock. The outbreak was discovered a week ago at a Tyson Foods chicken flock in Tennessee. Another case of bird flu was confirmed this week on a Wisconsin turkey farm.

In 2015, more than 48 million chickens and turkeys nationwide died from the disease.

The Oklahoma Department of Agriculture officials have reacted quickly. They say there are no confirmed cases in the state yet but stress owners should be prepared as birds start to migrate with the change of seasons.