Bird flu was probably circulating in dairy cows for at least four months before it was confirmed to be the highly pathogenic H5N1 virus, according to a new analysis of genomic data by scientists at the US Department of Agriculture’s Animal Disease Center.

CHICAGO (Reuters) - Bird flu likely circulated in U.S. dairy cows on a limited basis for about four months before federal officials confirmed the disease that has now spread to nine states, according to a new federally funded research paper.

By Lisa Baertlein, Julie Steenhuysen and Tom Polansek LOS ANGELES/CHICAGO (Reuters) - U.S. sellers of raw milk appear undeterred by federal health warnings for consumers to avoid drinking unpasteurized milk in light of a bird flu outbreak that has affected dairy herds in nine states and sickened at least one dairy farm worker.