DES MOINES, Iowa >> Poultry farmers who lost millions of chickens and turkeys to the bird flu this spring are facing an uncertain future.

The Des Moines Register reports the farmers aren’t sure when federal officials will allow them to start rebuilding their flocks or whether enough birds will be available.

Dave Rettig, president of Rembrandt Foods in Spirit Lake, Iowa, which lost 8 million egg-laying hens, said the disease struck quickly and it could return in the fall when birds are migrating.

"It came in like a tsunami and decimated the industry," he said. "And experts expect this virus to come back in the fall. Who knows where it will go? But it could impact the entire country."

Health officials have killed roughly 42 million egg-laying chickens and 7.5 million turkeys nationwide. Most of the birds killed have been in Iowa and Minnesota, but the disease has been confirmed in 15 states, including Nebraska.

Rettig said it will take at least a year or two for the industry to rebuild flocks, and he’s not sure when his business will be allowed to resume. Rembrandt Foods laid off 200 workers this spring.

"We can’t bring 40 million birds back overnight. The capacity just isn’t there," Rettig said.

Iowa Agriculture Secretary Bill Northey said he expects the U.S. Department of Agriculture to begin clearing the first few poultry firms to resume operations soon.

The Iowa Poultry Association says that if chickens return to farms before the end of the year, they could begin laying eggs early next year.

Demand for chickens was strong even before the bird flu hit, said Tom Jorgensen, general counsel at Hy-Line International.

"Demand for product is high, and product availability is low," he said.

Hy-Line expects demand for both chicks and breeding stock will surge quickly after farms are allowed to restart. Hy-Line ships about 100 million chicks annually.