Avian influenza A(H5N1) has been identified in United States wild birds, commercial poultry, and backyard flocks since January 2022. Recently, the first confirmed cases of H5N1 avian influenza infection were identified in wild birds in Orange County.

These H5N1 viruses have been termed highly pathogenic because they are associated with severe disease and high mortality in poultry. The risk of transmission to people is felt to be low. Two mild human infections with current H5N1 avian influenza viruses have been reported worldwide, including one case in the United States. Historically, some avian influenza A(H5N1) viruses have caused rare, sporadic infections in people, resulting in illness ranging from mild to severe respiratory disease. With the introduction of avian influenza into the county, providers should consider infection with these viruses in people presenting with influenza-like-illness (ILI) who have had significant exposure to sick or dead birds in the 10 days prior to symptom onset. If you are concerned about AI in a patient, testing can be arranged through the Orange County Public Health Laboratory (OCPHL).

• In patients presenting with ILI, providers should elicit any history of significant exposure to sick or dead birds in the 10 days prior to illness.
• Significant exposure includes:
• Being within 6 feet of birds with confirmed or suspect AI.
• Direct contact with surfaces contaminated with feces or tissues from dead infected birds.
• Inhaling dust or droplets from bird saliva, mucus, or feces from infected birds.
• Visiting live poultry markets with birds with confirmed or suspected infection.
• Unprotected exposure to a person with confirmed, probable, or suspect AI
• Providers should notify OCHCA Communicable Disease Control Division (CDCD) at 714-834-8180 if the history and clinical presentation raise concern of avian influenza infection.
• Suspect cases should be isolated at home in a single room. If hospitalized, standard, contact, and airborne precautions are required.
• Testing for AI can be conducted using the specimen type as used for seasonal influenza. A nasopharyngeal swab taken and placed in viral transport media with the submission specifically labeled that you are requesting testing for AI H5N1 virus. In contacting CDCD we can help expedite specimen transport and testing.
• Influenza antiviral treatment should be empirically started in people with suspected AI, for detailed guidance see Interim Guidance on the Use of Antiviral Medications for the Treatment of Human Infection with Novel Influenza A Viruses Associated with Severe Human Disease
• People who have been exposed infected birds or suspected human cases of AI who are asymptomatic should also be reported to CDCD and undergo active monitoring.

• California Department of Public Health - Avian and Novel Influenza Quicksheet
• CDC - Human Infection with Avian Influenza A Virus: Information for Health Professionals and Laboratorians
• CDC - Information on Bird Flu
• OC Health Care Agency - Avian Influenza