CHESTERFIELD COUNTY, S.C. (AP) — An infectious and fatal strain of bird flu has been confirmed in a commercial turkey flock in South Carolina, the first case of the more serious strain of the disease in the United States since 2017 and a worrisome development for an industry that was devastated by previous outbreaks.

The high pathogenic case was found at an operation in Chesterfield County, South Carolina, marking the first case of the more dangerous strain since one found in a Tennessee chicken flock in 2017. In 2015, an estimated 50 million…