SACRAMENTO, the United States -- California's battle against avian influenza A (H5N1) intensified amid spreading infections across dairy farms and a growing number of human infection, including two newly confirmed cases in Stanislaus and Los Angeles counties.

Bird flu virus has swept through farms across the nation’s largest dairy producing state. All human cases had been mild - until now.

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.

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. That raises new questions about the outbreak of the virus,

The case comes less than a week after Gov. Gavin Newsom called a state of emergency over the spread of bird flu virus in the state.

Public health officials are investigating the first human case of H5 bird flu detected in Los Angeles County, it was announced Monday. The victim, an adult who was exposed at a worksite to livestock infected with H5 bird flu,

CDC and NIAID Los Angeles County health officials reported the first human case of bird flu in the area less than a week after a statewide emergency declaration was announced. In a statement released on Monday,

Symptoms of H5 bird flu in humans include eye redness, fever, cough or difficulty breathing, sore throat, muscle or body aches, diarrhea and vomiting, according to DPH.