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, 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. Rare instances of limited non-sustained human-to-human HPAI H5N1 virus transmission have been reported.
Most patients with HPAI H5N1 virus infection present on hospital admission with fever and features of lower respiratory tract infection.
High case-fatality rate of approximately 53% among patients with laboratory-confirmed HPAI H5N1 virus infection.
Reverse transcription-PCR is the recommended diagnostic test. However, it is usually not available in most 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 specialized intensive care management are indicated for respiratory failure, ARDS, septic shock, multiorgan failure, and other severe complications of infection.
Infection control measures, such as standard, droplet, contact, and airborne precautions, are recommended.
The World Health Organization (WHO) defines avian influenza as 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.
[1]
Ungchusak K, Auewarakul P, Dowell SF, et al. Probable person-to-person transmission of avian influenza A (H5N1). N Engl J Med. 2005;352:333-340.
http://www.nejm.org/doi/full/10.1056/NEJMoa044021#t=article
http://www.ncbi.nlm.nih.gov/pubmed/15668219?tool=bestpractice.com
[2]
Wang H, Feng Z, Shu Y, et al. Probable limited person-to-person transmission of highly pathogenic avian influenza A (H5N1) virus in China. Lancet. 2008;371:1427-1434.
http://www.ncbi.nlm.nih.gov/pubmed/18400288?tool=bestpractice.com
This monograph is primarily focused on human infection with Asian lineage HPAI H5N1 virus.