Hospitalized Influenza Cases: Accelerated Influenza Subtyping and Recommendations for Idaho Healthcare Providers

In response to ongoing influenza A(H5N1) detections in wild birds and backyard flocks in Idaho, and recently reported human cases identified in other states, Idaho clinicians and clinical laboratories are requested to initiate or accelerate testing and subtyping of influenza virus from hospitalized patients to more quickly identify human infections with influenza A(H5N1) and to support appropriate infection control, optimal patient care, and timely case investigation. No human cases of influenza A(H5N1) have been identified in Idaho to date.

When feasible, influenza A positive respiratory specimens from hospitalized patients, especially from patients in an ICU, should be prioritized for subtyping as soon as possible following admission—ideally within 24 hours. If subtyping is not feasible onsite, arrangements should be made to send specimens out for subtyping. If subtyping is done, and a test result is positive for influenza A virus but negative for A(H1) and A(H3), then these specimens should be prioritized and shipped for influenza A(H5) subtyping at a commercial laboratory or the Idaho Bureau of Laboratories as soon as possible.

Commercial laboratories currently offering H5 subtyping are ARUP Laboratories, LabCorp, and Quest Diagnostics. Instructions on submitting specimens for subtyping at the Idaho Bureau of Laboratories can be found in the IBL Clinical Specimen Submission Guide.

Exposure history
Subtyping is especially important for hospitalized patients with suspected or confirmed influenza who have a history of possible exposure to avian influenza A(H5N1) viruses from wild birds, especially waterfowl, or from backyard flocks, or infected livestock.

Infection prevention
If avian influenza A(H5) virus infection is suspected, probable, or confirmed in a hospitalized patient, use standard, contact, and airborne precautions with eye protection (goggles or face shield). Contact the Idaho Healthcare-Associated Infections Program at HAI@dhw.idaho.gov or 208-334-5871 if you have questions about infection prevention.

Antiviral treatment
Any hospitalized patients, especially those in an ICU, with suspected seasonal influenza or avian influenza A(H5) should be started on antiviral treatment with oseltamivir as soon as possible without waiting for the results of influenza testing. Consider combination antiviral treatment for hospitalized patients with avian influenza A(H5) virus infection.

Reporting
Novel influenza A virus infections are reportable in Idaho. Notify Central District Health at 208-327-8625 or the Idaho Bureau of Environmental Health and Communicable Disease within one working day at 208-334-5939 if avian influenza A(H5N1) virus infection is suspected, probable, or confirmed in any patient.

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Resources
Avian Influenza (Bird Flu), for Health Care Providers. Centers for Disease Control and Prevention. https://www.cdc.gov/bird-flu/site.html#hcp
Influenza Diagnostic Tests. Food and Drug Administration. https://www.fda.gov/medical-devices/in-vitro-diagnostics/influenza-diagnostic-tests