By Tom Polansek

CHICAGO (Reuters) – U.S. trading partners on Friday limited shipments of poultry from Alabama, a top producer of chickens for meat, over bird flu concerns as the state’s wait for federal confirmation of two suspected cases stretched past a week.

The European Union, Kazakhstan and French Polynesia restricted shipments from Alabama counties with presumed cases of the disease, according to the U.S. Department of Agriculture’s website. The moves came a day after the state reported the agency’s national animal-health laboratories had confirmed a separate case of bird flu there.

Belarus blocked shipments from the entire state.

Alabama officials and poultry producers have been waiting since March 8 for the National Veterinary Services Laboratories (NVSL) to confirm the two suspected cases, which involve a commercial chicken farm and a backyard flock, according to the state. The facility in Ames, Iowa, is the only one in the United States that officially confirms cases of avian flu.

Swift confirmation is important for U.S. trading partners, some of which restrict shipments from geographic areas with infected flocks, and for state officials, who want to know which strain of the virus they are battling.

Highly pathogenic, or lethal, bird flu led to the deaths of about 50 million birds, mostly egg-laying hens, in the United States in 2014 and 2015.

Another widespread outbreak could be a financial blow for poultry operators, such as Tyson Foods Inc or Pilgrim’s Pride Corp, because it could kill more birds or require flocks to be culled.

The national labs must determine the strain and pathogenicity of the disease in order to officially confirm an infection, according to the USDA. The process often takes just a day.

A rapid test can be made when poultry samples contain sufficient genetic material, USDA spokeswoman Lyndsay Cole said on Thursday. But the samples from Alabama’s two suspected cases contained low levels, meaning scientists had to start a testing process that can take 14 days, she said.

Tests by a USDA-approved lab in Alabama and the national labs have already identified the H7 subtype of the virus from samples in the two suspected cases, she said.

“Our department respects the science behind the testing and is patiently waiting for accurate results,” said Amy Belcher, spokeswoman for Alabama’s agriculture department.

Alabama authorities presume the suspected cases are not highly lethal, or pathogenic, bird flu because the animals did not show signs of being sick. Still, officials have been checking birds at nearby farms for infections and the owners of the suspect flocks culled the birds, according to Alabama’s state veterinarian.

The United States must alert the World Organisation for Animal Health (OIE) if Alabama’s suspected cases are confirmed as positive, a step that could trigger more trade restrictions.

The OIE said “it is more important for the laboratory to be sure of its analysis than to be fast with it.”

(Additional reporting by Sybille de La Hamaide in Paris; Editing by Matthew Lewis)