California officials have declared a state of emergency over the spread of bird flu, which is tearing through dairy cows in that state and causing sporadic illnesses in people in the U.S.

Gov. Gavin Newsom’s declaration has riled up concern, particularly in other top dairy-producing states, such as Wisconsin and Pennsylvania.

California declared a state of emergency this week over the spread of bird flu in the state as the virus continues to be detected among the state’s cattle herds. California Gov. Gavin Newsom (D) said in a statement Wednesday that the declaration of an emergency is meant to “ensure government agencies have the resources

Bird flu, or avian influenza, is a rare but serious disease that can spread from birds to humans under certain conditions. So far, most cases have been confirmed through direct contact with infected birds or other animals,

California leaders and public health officials on Friday are expected to address the state’s response to the bird flu.