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Avian Influenza a(h5n1)

​​​Information for Health Professionals

Key Messages


  • Healthcare providers should consider avian influenza A(H5N1) in persons with acute respiratory symptoms and/or conjunctivitis and recent exposure to animals or humans suspected or confirmed to have avian influenza A OR recent consumption of raw dairy products. Of note, all cases among California dairy workers have had conjunctivitis.

  • ​​Providers should immediately report any suspected human avian influenza A(H5N1) infections to their  local health departments.

  • Testing of respiratory and conjunctival specimens for avian influenza A(H5N1) is available at some public health laboratories and commercial laboratories.

  • Antiviral treatment is recommended for patients suspected or confirmed to have avian influenza A(H5N1) infection and antiviral prophylaxis is recommended for their close (e.g., household) contacts.

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


​Situational Update 

H​​uman Cases 

For up-to-date information about confirmed cases in California, visit CDPH's Bird Flu webpage. For national information, visit CDC H5 Bird Flu: Current Situation.

The risk to the gene​​ral public remains low. However, people with job-related or other close and prolonged exposures to infected birds, cows, or other animals are at higher risk of infection.   ​

Animal Cases

For California specific livestock updates visit CDFA H5N1 Bird Flu Virus in Livestock and for poultry updates visit CDFA - Avian Influenza. 

For national detections in livestock, visit USDA HPAI Confirmed Cases in Livestock. For national detections in poultry, visit USDA Confirmations of Highly Pathogenic Avian Influenza in Commercial and Backyard Flocks.

Recommendations

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 and/or conjunctivitis; AND  
    • A history of exposure in the last 10 days to animals or humans suspected or confirmed to have avian influenza A(H5N1), or who have had exposure to raw milk.  

​​If you encounter patients who work with infected animals, please encourage them to use ​personal protective equipment (PPE) and suggest they receive seasonal influenza vaccine during influenza season.  

 ​

​Specimen Collection and Testing  

  • ​​​​Healthcare providers who suspect influenza A (H5N1) virus infection should immediately reach out to the local health department (LHD) of the patient's residence. The LHD can help determine if testing is warranted, recommend appropriate specimens to collect based on symptomatology, and coordinate testing at a public health or commercial laboratory that can perform H5 subtyping (if appropriate).  
  • Influenza PCR testing at clinical or commercial laboratories can detect influenza A, but hemagglutinin subtyping must be done to detect influenza A(H5N1) virus (or rule it out by detecting H3 or H1 influenza A) in an influenza A positive specimen.   
  • When concern for detecting influenza A(H5N1) infection is high, testing should be sent to a public health laboratory for timely public health response (e.g., symptomatic farm workers exposed to infected animals or symptomatic persons exposed to a confirmed human case).
    • Commercial PCR tests for influenza can be used to rule out influenza A (and therefore H5N1) infection in symptomatic people less likely to be infected with influenza A(H5N1) (e.g., symptomatic people with limited animal exposure, or no known exposure to infected animals or humans).
      • Testing at a commercial laboratory offering testing for influenza A H5 subtyping can also be ordered for low suspicion patients. 
  • ​​​​​​Ideally collect specimens within 24–72 hours of symptom onset and no later than 10 days after symptom onset in persons who meet the exposure criteria and have avian influenza A(H5N1) infection symptoms. If more than 10 days have elapsed since symptom onset, then consideration of testing may occur on a case-by-case basis and in discussion with CDPH.
  • The following specimens should be collected: ​​​​​
    • ​Respiratory specimens 
      • Separate oropharyngeal and anterior nares swabs are preferred (combining both swabs into a single transport media tube is also acceptable). 
      • Nasopharyngeal swabs are acceptable, but have had a lower yield for positive test results in cases than oropharyngeal or anterior nares swabs to date.  
    • Conjunctival swabs should also be collected if the patient has conjunctivitis. Conjunctival swabs have had the highest yield for detection in cases to date.  
      • If both eyes are affected, each eye should be swabbed with a separate swab but both swabs should be placed in a single transport media tube.  
    • Patients with severe respiratory disease should have multiple respiratory tract specimens obtained from additional sites (e.g., endotracheal aspirate, bronchoalveolar lavage, sputum) to increase the potential for avian influenza A(H5N1) virus detection.
  • For more information on specimen collection and transport, see CDPH VRDL’s Test Order Page for “Novel/Avian Influenza Virus Detection (human) – PCR"​. 
  • For further information about laboratory testing for influenza A(H5N1), please contact the laboratory that will be conducting testing as specimen submission procedures at each laboratory may vary. 
  • For further information about laboratory testing for influenza A(H5N1) at the CDPH state laboratory, please refer to the CDPH Viral and Rickettsial Diseases Laboratory (VRDL) website, email questions to VRDL.submittal@cdph.ca.gov, or call the VRDL at 510-307-8585  (M-F, 9am – 5pm Pacific Time, excluding holidays). ​ 


​Treatment 

Chemoprophylaxis 

  • ​Chemoprophylaxis dosing for influenza A (H5N1) is the same as treatment dosing: 75 mg twice daily for adults for 5 days if there has been a time-limited exposure OR 10 days if exposure is ongoing. 
    • Dosage adjustment is needed for children, infants, neonates and adult patients with renal impairment.  
  • Prophylaxis is recommended for household contacts of confirmed cases and can be considered in workers to infected or potentially infected cows who have had an unprotected discrete high-risk exposure such as a milk splash to the eye. 
    • Consideration for prophylaxis should be based on clinical and public health considerations such as type and duration of exposure, time-course, infection status of animal or human exposure and if person is at increased risk for complications with seasonal influenza​. 

​Healthcare Infection Prevention and Control

  • If a case is suspected, immediately mask the patient and place them in an airborne infection isolation room (AIIR) with the door closed. While in an AIIR, the patient’s mask may be removed. 
  • If an AIIR is not available, place the patient in a single-patient room with the door closed and have the patient remain masked.  
  • Use personal protective equipment that includes: 
    • Respiratory protection (fit-tested N95 respirator or higher level of protection) 
    • Eye protection (goggles or face shield) 
    • Gown and gloves 
  • Use diligent hand hygiene before and after contact with the patient. ​
  • Limit room entry to essential personnel. Limit transport of patient outside their room.   
  • If a non-AIIR room is used, after the patient leaves, the room should not be reused and unprotected individuals should not enter until sufficient time has elapsed for enough air changes to remove potentially infectious particles, per CDC guidance. For example, in a patient-care area with six air exchanges per hour, the time to removal of airborne contaminants with 99.9% efficiency is 69 minutes. 

For additional infection control recommendations, see CDC Interim Guidance for Infection Control Within Healthcare Settings When Caring for Confirmed Cases, Probable Cases, and Cases Under Investigation for Infection with Novel Influenza A Viruses Associated with Severe Disease. ​

For applicable Cal/OSHA requirements in healthcare settings, please see California’s Aerosol Transmissible Diseases standard.  

​​Resources

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