The Food and Drug Administration says remnants of the bird flu were found in one in five pasteurized milk samples. Earlier this week, the FDA found fragments of the bird flu in commercially sold milk but said it’s still safe to drink, as the pasteurization process kills the virus and only leaves small traces behind. On Thursday officials revealed about 20-percent of their milk samples contained remnants of the virus. The Department of Agriculture has ordered all dairy cows transported over state lines be tested.

The USDA has confirmed cases of the Avian Influenza, also known as the Bird Flu, in dairy cows in northeastern Colorado. The department says the cows were tested for the virus after they showed the tell-tale signs of the illness, and the results came back positive. USDA officials say because milk products are pasteurized before entering the market, there is no health risk to consumers. Bird Flu cases have also been confirmed in cows in eight other U.S. states.

The Illinois Department of Agriculture and the Illinois Department of Public Health are on alert following the detection of the H5N1 influenza virus in dairy herds in eight states across the U.S. There are no confirmed cases reported in Illinois. The U.S. Food and Drug Administration emphasizes that the commercial milk supply is safe because of the pasteurization process, which destroys bacteria and viruses in milk. Illinois is home to more than 600 dairy farms.