Highly pathogenic bird flu has been detected in a commercial turkey in South Carolina, the first time the deadly poultry disease has been found in the U.S. since 2017, the USDA reported Thursday.

The strain apparently mutated from a low pathogenic strain of H7N3 avian influenza that broke out in turkey barns on both sides of the South Carolina-North Carolina border in March, according to the USDA.

South Carolina officials have quarantined the turkey farm in Chesterfield County, and the turkeys were euthanized, USDA said. The agency said it would notify the World Organization for Animal Health.

The USDA has previously reported to the world organization that low pathogenic bird flu was detected in 11 commercial turkey operations in North Carolina and South Carolina. Some 310,000 turkeys had been destroyed, according to the USDA.

Many countries in response banned poultry from the infected counties, but had not imposed broader trade sanctions.

A bird flu outbreak that began in British Columbia in late 2014 and then spread to Washington, Oregon and California before leapfrogging across the U.S., claimed 48 million birds.