The Food and Drug Administration has started testing aged raw cow’s milk cheese for Highly Pathogenic Avian Influenza (H5N1), otherwise known as bird flu.

The FDA says it started the testing in response to a bird flu outbreak in several states that is impacting poultry, dairy cows and people across the U.S.

Raw milk cheese is made with unpasteurized milk. In the United States cheese allowed to be made from raw milk must be aged for a minimum of 60 days to mitigate the risk from any pathogens, if present.

FDA field staff will collect hundreds of samples from warehouses and distribution hubs throughout the country. It will not collect samples at retail locations.

An elderly patient in Louisiana was hospitalized with severe avian influenza earlier in the month, the first serious human case in the country as fears grow of a possible bird flu pandemic.

The Centers for Disease Control and Prevention says it appears the bird flu virus mutated in the victim.

The mutations could make it easier for the virus to infect the upper airways of humans.

The new case brings the total number of infections in the United States during the current 2024 outbreak to 61, with other patients experiencing mild symptoms they recovered from at home.