Federal health officials say a dairy worker in Nevada has been infected with a new type of bird flu that’s different from the version that has been spreading in U.S. herds since last year.

Nevada just confirmed its first human case of avian flu from infected cattle. Nevada’s first case was found in Churchill County, the Central Nevada Health District announced on Monday.

An emerging strain of highly pathogenic avian influenza has spilled over from wild birds to dairy cows in the state of Nevada, and officials at the US Department of Agriculture (USDA) and some scientists are concerned by a mutation they are seeing.