Highly pathogenic bird flu has made its first appearances in U.S. commercial poultry flocks this season, affecting one turkey farm in South Dakota and one in Utah and raising concerns that more outbreaks could follow.

The U.S. Department of Agriculture reported that avian influenza, which is deadly to commercial poultry, was confirmed in a flock of 47,300 turkeys in Jerauld County, South Dakota, on Oct. 4 and at a farm with 141,800 birds in Utah’s Sanpete County last Friday.

The outbreaks are the first reported among commercial flocks in the U.S. since the disease struck two turkey farms in the Dakotas in April. Infected flocks are normally destroyed to prevent the flu’s spread, and then the farms are decontaminated.