​​Key Messages​​

• ​​​​Avian influenza A(H5N1) has been confirmed in cows at three California dairies located in the Central Valley. 

• ​​​Healthcare providers should consider avian influenza A(H5N1) in persons with acute respiratory symptoms and/or conjunctivitis and recent exposure to animals suspected or confirmed to have avian influenza.

• ​​Providers should immediately report any suspected avian influenza infections to their local health departments.
  

Testing of respiratory and conjunctival specimens for avian influenza is only available at public health laboratories and requires coordination with your local health department.


Antiviral treatment is recommended for patients suspected or confirmed to have avian influenza A(H5N1) infection.


Healthcare providers should follow standard, contact, and airborne precautions​ when caring for patients suspected of having avian influenza A(H5N1) infection. ​

​​Situational Update

On August 30, 2024, the California Department of Food and Agriculture (CDFA) announced that cows at three California dairies located in the Central Valley tested positive for highly pathogenic avian influenza (HPAI) A(H5N1). To date there have not been any confirmed human infections of avian influenza A(H5N1) in California, and the current risk to the public remains low. However, people with job-related or recreational exposures to infected birds, cattle, or other animals are at higher risk of infection.  

​Background

Avian influenza A (H5N1) has been detected in multiple U.S. dairy herds since March 2024. From April 1 to August 30, 2024, the Centers for Disease Control and Prevention (CDC) has confirmed four human HPAI A(H5N1) infections among commercial dairy workers in Texas (1), Michigan (2), and Colorado (1), with suspected cow-to-human transmission. All persons had mild symptoms; four had conjunctivitis and one reported upper respiratory symptoms. No human-to-human transmission has been identified thus far. No confirmed human cases of avian influenza A(H5N1) have been identified in California. 

​Recommendations for Healthcare Providers

​​​Consider Avian Influenza Infection

• Healthcare providers should consider the possibility of avian influenza A(H5N1) virus infection in a patient with signs and symptoms consistent with acute respiratory tract infection or conjunctivitis and history of exposure in the last 10 days to animals suspected or confirmed to have avian influenza. 

• If you encounter patients working with ill animals, please encourage them to use ​personal protective equipment (PPE) and suggest they get a seasonal flu vaccine. 

​Specimen Collection and Testing 

• ​​Healthcare providers who suspect avian influenza A (H5N1) virus infection should immediately reach out to their local health department (LHD). The LHD can help determine if testing is warranted and coordinate testing at a public health laboratory. 

• ​Testing of clinical specimens for avian influenza A(H5N1) virus can only be performed at a public health laboratory. Testing at a clinical or commercial laboratory cannot rule out avian influenza virus infection.   

• Specimens should ideally be collected within 24–72 hours of symptom onset and no later than 10 days after symptom onset. ​​​​​

• Respiratory specimens (e.g., nasopharyngeal swabs, nasal swabs, throat swabs, or dual nasopharyngeal/throat swabs) should be collected from people experiencing any symptoms potentially associated with avian influenza. 

• A conjunctival swab should also be collected from anyone experiencing conjunctivitis. A conjunctival swab MUST be paired with a nasopharyngeal swab even if the person does not have respiratory symptoms. 

• Specimens should be collected using swabs with synthetic tips (e.g., polyester or Dacron®) and an aluminum or plastic shaft. 

• Swabs with cotton tips and wooden shafts are NOT recommended. 
  

• Specimens collected with swabs made of calcium alginate are NOT acceptable. ​​​​

• ​​​​​​​Swabs should be placed in specimen collection vials containing 2–3ml of viral transport media (VTM) or universal transport media (UTM). 
  

• Specimens should be refrigerated or frozen after collection. Refrigerated specimens should be transported to the public health lab on cold packs. Frozen specimens should be transported on dry ice. 
  

• For further information about laboratory testing for influenza A(H5), please refer to the CDPH Viral and Rickettsial Diseases Labotoratory (VRDL) website or call the VRDL at 510-307-8585. ​
  

​Treatment

​PPE and Infection Control

​Resources