Over the weekend, California state health officials warned the public to avoid drinking raw milk from a Fresno-based dairy farm that was being sold in stores. H5N1, the virus driving the current bird flu outbreak, was detected in a retail milk sample.

Bay Area grocery stores are pulling some raw milk off their shelves after traces of the bird flu virus were found last week in a batch of unpasteurized milk out of Fresno County. Here's what to know.

The sample obtained at a store tested positive Nov. 21 during routine screening by Santa Clara County health officers.