Avian Influenza A (H5N1): Recommendations for Screening & Initial Management of Suspect Human Cases

Testing for avian influenza A (H5N1) is indicated for hospitalized patients with:

• Radiographically confirmed pneumonia, acute respiratory distress syndrome or other severe respiratory illness for which an alternative diagnosis has not been established; AND
  
• History of travel within 10 days of symptom onset to a country with documented avian influenza A (H5N1) infections in poultry and/or humans.

Testing for avian influenza A (H5N1) should be considered on a case-by-case basis (consult with Public Health) for hospitalized or ambulatory patients with:

• Influenza-like illness (ILI): Temperature >100.4°F (>38°C) PLUS one or more of the following: cough, sore throat, or shortness of breath; AND
• History of contact with poultry (e.g., visited a poultry farm, a household raising poultry, or a bird market) or a known or suspected human case of influenza A (H5N1) in an H5N1-affected country within 10 days prior to onset of symptoms.

Regularly updated listings of H5N1-affected countries are available at the World Organization for Animal Health [OIE] website at www.oie.int/eng/en_index.htm; the WHO website at www.who.int/en and the CDC’s avian influenza outbreak website at www.cdc.gov/flu/avian/outbreaks/asia.htm).

When a patient meets both clinical and epidemiologic criteria for a suspected case of novel influenza:

• Implement infection control precautions: Patients should be placed on Droplet Precautions for a minimum of 14 days, unless there is full resolution of illness or another etiology has been identified before that period has elapsed. Healthcare personnel should wear surgical or procedure masks on entering a patient’s room, as per Droplet Precautions, as well as gloves and gowns, when indicated for Standard Precautions. Patients should be admitted to a single-patient room, and patient movement and transport within the hospital should be limited.
  
  
• Notify Public Health: Report each patient who meets the clinical & epidemiologic criteria for a suspected case of novel influenza as quickly as possible to facilitate lab testing & initiation of public health measures.
  
  
• Obtain clinical specimens for testing by the Washington State Public Health Laboratory (WA PHL): If feasible, all of the following specimens should be collected for novel influenza A virus testing: throat swab, nasopharyngeal swab; nasal swab, wash, or aspirate; and tracheal aspirate (for intubated patients). Store specimens at 4°C in viral transport media. Acute (within 7 days of onset) & convalescent serum specimens (2–3 weeks after the acute specimen and >3 weeks after onset) should be obtained & refrigerated at 4°C or frozen at minus 20–80°C.

IMPORTANT: Avian influenza can be identified by RT-PCR at the WA PHL ONLY after reporting the case to Public Health at 206-296-4774.  WA PHL will not accept specimens for testing without prior approval from Public Health – Seattle & King County. 

Although some commercial laboratories may offer PCR testing for novel influenza viruses, these tests are not standardized and results from these laboratories will not be interpretable without confirmatory testing at the WA PHL.  For this reason, at this time Public Health does not recommend specimens be submitted to commercial laboratories for novel influenza virus testing.

Viral culture of specimens from suspected novel influenza cases can be attempted only in laboratories that meet the biocontainment conditions for BSL-3 with enhancements or higher (CDC) and should not be attempted in clinical laboratories.

Rapid influenza diagnostic tests and immunofluorescence (IF) tests may be used to detect seasonal influenza, but should not be used to confirm or exclude novel influenza during the Pandemic Alert Period. Rapid influenza tests have relatively low sensitivity for detecting seasonal influenza, and their ability to detect novel influenza subtypes is unknown. Such tests cannot distinguish between infection with seasonal and novel influenza A viruses. A negative rapid influenza test result does not necessarily exclude infection with either seasonal or novel influenza A viruses, and a positive rapid influenza test result could be a false positive or represent infection with either seasonal or novel influenza A viruses. Therefore, both negative and positive rapid influenza test and IF results should be interpreted with caution.  Acute and convalescent serum samples and other available clinical specimens (respiratory, blood, and stool) should be saved and refrigerated or frozen for additional testing until a specific diagnosis is made.

• Evaluate alternative diagnoses.  If an alternate etiology is identified, the possibility of co-infection with a novel influenza virus may still be considered if there is a strong epidemiologic link to exposure to novel influenza.
  
  
• Decide on inpatient or outpatient management. The decision to hospitalize a suspected novel influenza case will be based on the clinical assessment, assessment of risk, and whether adequate precautions can be taken at home to prevent the potential spread of infection. Patients cared for at home should be separated from other household members as much as possible. All household members should carefully follow recommendations for hand hygiene, and tissues used by the ill patient should be placed in a bag and disposed with other household waste. Consult with Public Health before discharging any patient with suspected avian influenza A (H5N1).
  
  
• Initiate antiviral treatment as soon as possible, even if laboratory results are not yet available. Clinical trials have shown that these drugs can decrease the illness due to seasonal influenza duration by several days when they are initiated within 48 hours of illness onset. The clinical effectiveness of antiviral drugs for treatment of novel influenza is unknown, but it is likely that the earlier treatment is initiated, the greater the likelihood of benefit.

For additional information, including a FLOW CHART for case detection and initial management, and other pandemic resources, see Public Health’s Pandemic Flu Web Page: at www.metrokc.gov/health/pandemicflu