State officials say the highly pathogenic avian influenza – more commonly known as bird flu – is widespread in much of the state.

A version of the H5N1 virus that has killed one person and severely sickened another has been detected in milk samples collected from Nevada dairy herds.

The U.S. Department of Agriculture has detected a bird flu strain in dairy cattle that previously had not been seen in cows, the agency's Animal and Plant Health Inspection Service said on Wednesday.

The USDA said four Nevada dairy herds were infected with an H5N1 bird flu strain which has circulated in wild birds, making prospects for containment in cows appear dim.