​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 

• ​​​Healthcare providers who suspect influenza A(H5N1) virus infection should refer to the CDC's Interim Guidance on the Use of Antiviral Medications for Treatment of Human Infections with Novel Influenza A Viruses Associated with Severe Human Disease and the CDC Emergency Use Instructions for Oseltamivir.  
• Antiviral treatment is recommended as soon as possible for patients with suspected or confirmed influenza A(H5N1) virus infection.  Antiviral treatment should not be delayed while waiting for laboratory test results.  
• The standard treatment dose of oseltamivir is 75 mg twice daily for 5 days for adults.  
• ​Dosage adjustment is needed for children, infants, neonates and for adult patients with renal impairment.
• Oseltamivir is not recommended for people with end-stage renal disease who are not receiving dialysis.  
• Pending further data, longer courses of treatment (e.g., 10 days) should be considered for severely ill hospitalized patients with novel influenza A virus infections. For additional information, please see the Emergency Use Instructions (EUI) Fact Sheet for Healthcare Providers. 

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​.