Last reviewed: 24 Dec 2021
Last updated: 18 Jan 2022



History and exam

Key diagnostic factors

  • cough
  • influenza-like illness
  • dyspnea
  • fever
  • rales, rhonchi
  • wheeze
  • decreased breath sounds
  • tachypnea

Other diagnostic factors

  • abdominal pain, vomiting, diarrhea
  • altered mental status
  • seizures

Risk factors

  • close contact with infected birds
  • recent travel to an HPAI-H5N1 virus infected country
  • environmental exposure to H5N1 virus
  • close contact with infected humans
  • laboratory work with H5N1 virus

Diagnostic investigations

1st investigations to order

  • CBC with differential
  • LFTs
  • chest x-ray
  • pulse oximetry
  • sputum Gram stain
  • sputum and blood bacterial culture
  • reverse transcription polymerase chain reaction (RT-PCR) of respiratory specimens

Investigations to consider

  • viral culture of respiratory specimens

Emerging tests

  • serologic testing for H5N1-specific antibody for retrospective diagnosis

Treatment algorithm



Justin R. Ortiz, MD, MS

Affiliate Assistant Professor of Medicine & Global Health

University of Washington




JRO received honorarium from Pfizer for speaking on adult immunization policies at the 2019 Immunisation for All Ages Summit and participation on the Immunisation for All Ages Steering Group. JRO has participated on the Global Influenza Hospital Surveillance Network for Sanofi and has received honorarium from the International Federation on Aging for speaking about adult immunization policies at the 2019 United Nations International Day of Older Persons side event “End Immunisation Inequality Toward Healthy Aging”. JRO receives research grants and contracts to evaluate influenza vaccines from the National Institutes of Health and has served as a medical monitor for a cholera vaccine study for Pharmaron.

Timothy M. Uyeki, MD, MPH, MPP

Chief Medical Officer

Influenza Division

National Center for Immunization and Respiratory Diseases

Centers for Disease Control and Prevention




TMU declares that he has no competing interests.

Peer reviewers

Waleed Javaid, MD, FACP, FIDSA

Associate Professor

Medical Director of Infection Control

Infectious Disease

Department of Medicine

SUNY Upstate Medical University




WJ declares that he has no competing interests.

An De Sutter, MD, PhD

Associate Professor

Department of General Practice and Primary Health Care

Ghent University



ADS declares that she has no competing interests.

Nayer Khazeni, MD, MS

Assistant Professor

Pulmonary & Critical Care Medicine


Center for Health Policy/Center for Primary Care & Outcomes Research

Stanford University School of Medicine




NK declares that she has no competing interests.

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