​Specimen Collection and Testing  

• ​​​​Healthcare providers who suspect influenza A (H5N1) virus infection should immediately reach out to their local health department (LHD). 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 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. 

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

• Respiratory specimens for submission to a public health laboratory* 

• 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 to date have had a lower yield for positive test results in cases than oropharyngeal or anterior nares swabs.  

• ​A conjunctival swab should also be collected from anyone experiencing conjunctivitis, and has 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. 

• Conjunctival swabs MUST be paired with oropharyngeal and anterior nares swab specimens or a nasopharyngeal swab specimen, even if the person does not have respiratory symptoms.  

• ​If the symptomatic person consumed raw dairy products and has gastrointestinal symptoms (with or without respiratory symptoms), stool should also be collected, if possible, and held for potential testing for enteric pathogens, as well as testing for influenza A if it becomes available.   ​
  

• 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 contact the laboratory that will be conducting testing as specific requirements for acceptable specimens at each laboratory vary. 

• For further information about laboratory testing for influenza A(H5) 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). ​ 

*Commercial laboratories may have differen​t specimen submission recommendations for H5 subtyping than public health laboratories. ​

​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​.