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.

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.

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. The infected person — who showed signs of conjunctivitis but had no other symptoms — is recovering.

The newer variant of avian influenza that recently infected dairy cattle in Nevada has a genetic change that’s thought to help the virus copy itself in mammals — including humans — more easily, according to a new technical brief from the US Department of Agriculture’s Animal and Plant Health Inspection Service.

The Central Nevada Health District is confirming the first and only known case of avian flu infection in Nevada.

A dairy worker in Nevada is the state’s first human case of bird flu after the employee was exposed to infected dairy cattle. In a release Monday, the Central Nevada Health District

Six dairy herds in Nevada have tested positive for a newer variant of the H5N1 bird flu virus that’s been associated with severe infections in humans, according to the Nevada Department of Agriculture.

Dairy herds in Nevada have been infected by a version of the H5N1 bird flu not previously seen in cows, putting virologists on high alert.