U.S. regulators announced on May 20 that they had tested milk and other dairy products from retail stores in 17 states for the highly pathogenic avian influenza.

The U.S. Food and Drug Administration (FDA) collected 297 samples of milk and other products such as sour cream from grocery stores in 17 states, the agency said in an update.

None of the states were identified. The samples represented products produced at 132 different locations across 38 states, including Arizona, California, Florida, Kansas, and Texas. “The location of where milk was processed does not indicate where the milk was produced.

This is because milk could be produced from cows on a farm or farms a few states away, processed (pasteurized) in a different state, and then be available for purchase in yet another state,” the FDA said in a statement. FDA officials said earlier this month that some milk samples from retailers tested positive for the influenza, also known as the bird flu. The quantitative real-time polymerase chain reaction (qRT-PCR) tests used can detect remnants of a virus, indicating past infection.

The FDA said that follow-up testing identified no live virus in the samples and maintained the nation’s milk supply is safe. In the update on Monday, the FDA said 1 percent milk was most likely to test positive. Out of 1 percent milk samples, 32.

1 percent tested positive, compared with 27.6 percent of 2 percent milk samples, 23.5 percent of whole milk samples, and 11.

1 percent of skim milk .