Summary

• Contagious disease of animals caused by avian influenza A viruses that infect birds. Less commonly, other animals, including pigs, can be infected. Rare sporadic transmission from birds to humans can occur.
• Key risk factors for human infection include close or direct contact with infected birds or infected ill humans, visiting a live poultry market in endemic areas, or living in an area where highly pathogenic avian influenza (HPAI) A H5N1 viruses are circulating among poultry.
• Most patients with HPAI H5N1 virus infection present on hospital admission with fever and features of lower respiratory tract infection.
• High case-fatality proportion of almost 60% among patients with laboratory-confirmed HPAI H5N1 virus infection.
• Reverse transcription-PCR is the recommended diagnostic test. However, it is usually not available in clinical settings.
• Oseltamivir, administered as early as possible, is the recommended antiviral treatment for ill patients with suspected or confirmed infection. Zanamivir might be used as an alternative. Supportive care and specialised intensive care management are indicated for respiratory failure, ARDS, septic shock, multi-organ failure, and other severe complications of infection.
• Infection control measures, such as standard, droplet, contact, and airborne precautions, are recommended.