On Dec. 6, 2024, the Arizona Department of Health Services reported the first human H5N1 cases in Arizona. Both individuals were exposed to infected poultry while working at a commercial facility in Pinal County. These individuals reported mild symptoms, received treatment and recovered. 

Avian influenza has been detected in Arizona, including a commercial poultry farm in Pinal County and a backyard flock in Maricopa County. Most human infections with H5N1 virus have occurred after unprotected exposure to sick or dead infected animals or their environment. Human infections with H5 can happen when the virus gets in a person’s eyes, nose, mouth or is inhaled from close or prolonged exposure to sick animals or their environments. 

Avian influenza H5N1 is a novel influenza A virus that primarily affects birds. Although human infections with H5N1 are rare, exposure to animals infected with influenza N1A(H5) or environments in which infected animals have been present increase the risk of individuals becoming infected.