One of the top egg producers in the U.S. confirmed that a farm tested positive for cases of bird flu over the weekend, the company said in a statement Tuesday.

First U.S. detection of virulent H5N9 strain, at a California duck farm, draws scrutiny as evidence of genetic reassortment that could trigger human outbreaks.

If you’ve been to the store recently and feel like you’re spending more money on eggs than in the past, you are not alone. A recent outbreak of avian influenza, or bird flu, has disrupted egg production in the United States.

Health officials urged people to identify avian flu symptoms early and properly cook chicken and eggs to limit risk of infections.

Avian, or bird, flu continues to spread across the United States, mostly at poultry and cattle farms. Poultry farmers and people with backyard flocks can protect their animals and themselves by limiting exposure to wild birds.

The United States reported a first outbreak of H5N9 bird flu on a poultry farm, the World Organisation for Animal Health said on Monday. Highly pathogenic avian influenza, commonly called bird flu, has spread around the globe in the past years,

The H5N9 strain of avian influenza is much more rare than the H5N1 which has been responsible for most of the reported human cases and the first human death.

A new strain of H5N9 bird flu was detected at a commercial duck operation in California's Merced County. All the ducks were euthanized.