Avian influenza (H5N1) virus infection is a notifiable condition. Infection control measures such as patient isolation and standard, contact, and airborne precautions are recommended.
High case-fatality rate of approximately 53% among patients with laboratory-confirmed infection.
Most patients present with fever and features of lower respiratory tract infection on admission. Molecular testing is recommended to confirm diagnosis; however, it is usually not available in most clinical settings.
Antiviral therapy is recommended as soon as possible in unwell patients with suspected or confirmed infection. Supportive care and specialised intensive care management are indicated for respiratory failure and other severe complications.
A contagious disease of animals caused by viruses that infect birds and, less commonly, pigs. Avian influenza A viruses are highly species-specific but have infected other mammals and, on rare occasions, have crossed the species barrier to infect humans. Highly pathogenic avian influenza (HPAI) A H5N1 virus originating in poultry and wild birds can be transmitted to humans, with rare cases of infection transmitted between humans.
This topic focuses on human infection with Asian lineage HPAI H5N1 virus; avian influenza A (H7N9) infection is covered in a separate topic.
History and exam
Key diagnostic factors
- presence of risk factors
- influenza-like illness
- rales, rhonchi
- decreased breath sounds
Other diagnostic factors
- abdominal pain, vomiting, diarrhoea
- altered mental status
- 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
1st investigations to order
- FBC with differential
- chest x-ray
- pulse oximetry
- sputum Gram stain
- sputum and blood bacterial culture
- reverse transcription polymerase chain reaction (RT-PCR)
Investigations to consider
- viral culture
close contact of confirmed or probable case
suspected or probable or confirmed infection
- Coronavirus disease 2019 (COVID-19)
- Community-acquired pneumonia
- Atypical pneumonia
- Interim guidance for infection control within healthcare settings when caring for confirmed cases, probable cases, and cases under investigation for infection with novel influenza A viruses associated with severe disease
- Interim guidance on influenza antiviral chemoprophylaxis of persons exposed to birds with avian influenza A viruses associated with severe human disease or with the potential to cause severe human disease
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