Bird flu has been reported in two more states beyond Minnesota, including at a central Missouri farm raising birds for Cargill Inc., one of the country's biggest turkey producers.

The fast-spreading, highly fatal H5N2 avian influenza virus most recently surfaced in a commercial flock of 40,000 turkeys in northwestern Arkansas, the U.S. Department of Agriculture confirmed Wednesday.

On Tuesday, the USDA reported bird flu at two separate turkey farms in Missouri, including the one operating under contract to Minnetonka-based Cargill. Last week, the highly pathogenic bird flu landed in Minnesota for the first time, wiping out 15,000 turkeys at a breeding farm in Pope County in the state's west central region.

A similar bird flu strain has been reported in Washington, Oregon and Idaho. While it's not seen as a threat to human health, the H5N2 virus could inflict major damage on the poultry industry — both turkey and chicken producers — if it spreads widely.

"Everybody is on full alert because obviously this has a high mortality rate," said Mike Martin, a Cargill spokesman. "It's not exclusive to Cargill. It's industrywide."

Indeed, stocks of poultry processors took a hit Wednesday on heavy trading volume as bird flu fears spread.

"It's definitely having an impact," said Brian Yarbrough, a stock analyst at Edward Jones. He added that it's "way too early to tell" if the flu will hurt production. Still, a few dozen countries have banned turkey imports from several U.S. states, including Minnesota.

Tyson Foods' stock fell more than 5 percent Wednesday, while shares of Sanderson Farms and Pilgrim's Pride dropped 4 percent. Austin-based Hormel Foods' stock declined 1.8 percent.

Hormel is a major turkey processor, and its Jennie-O brand is perhaps the best-known national turkey brand. Most of Hormel's birds are raised in Minnesota, the nation's top turkey-producing state.

The flu situation in Minnesota "does not involve Jennie-O at present, and we have no flocks within the quarantine zone," Hormel said in a statement. A six-mile quarantine surrounds the affected Pope County turkey breeder.

The bird flu virus is being spread by wild birds who themselves don't get sick. But their feces, when somehow tracked into a poultry barn, carry the virus that then infects turkeys and chickens. The virus spreads very quickly in flocks.

At the Fortuna, Mo., farm that raises turkeys for Cargill, a flock of 12,000 birds spread across two barns was almost wiped out in about two days, Martin said.

Cargill, like other turkey producers, immediately increased biosecurity measures at its turkey operations, including adopting stricter sanitation measures. With an animal virus, producers must be careful the bug isn't spread from farm to farm.

Cargill also tested all of its nearly 80 turkey flocks within a 12-mile radius of Fortuna. None tested positive for the flu, Martin said.

Cargill has about 700 contract turkey growers across the country, but with a high concentration in Arkansas, Missouri and Virginia. The contract growers own their farms, but Cargill owns the turkeys and supplies the birds' feed.

The Wall Street Journal reported Wednesday that North Carolina-based Butterball, another large U.S. turkey processor, had confirmed that a "limited number" of turkeys on its contract farms had been diagnosed with H5N2.