(SIOUX FALLS, S.D., AP) — A bird flu strain that’s deadly to poultry has shown up in a commercial turkey flock in South Dakota and a fourth turkey farm in Minnesota.

The U.S. Department of Agriculture said Thursday it has confirmed the H5N2 strain in a flock of 53,000 turkeys in eastern South Dakota, and a fourth Minnesota case in the southwest part of the state involving a commercial turkey farm with about 21,000 birds.

The birds at both places have been quarantined and will be killed to prevent the disease’s spread.

Minnesota was the first to see the H5N2 strain in the Mississippi Flyway, a major wild bird migration route, followed by flocks in Arkansas and Missouri.

Kansas was the first to see H5N2 in the Central Flyway, now followed by South Dakota.