Avian influenza A (H5N1) virus infection

Avian influenza (H5N1) virus infection is a notifiable condition. Infection control measures, such as standard, droplet, 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 specialized 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.[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 topic focuses on human infection with Asian lineage HPAI H5N1 virus; avian influenza A (H7N9) infection is covered in a separate topic.

BMJ talk medicine podcast: avian influenza - a guide to recognition, reporting and referral with Dr Mary-Margaret Fill