Avian influenza A(H5N1): For health professionals

Key information

Outbreaks of avian influenza A(H5N1) in domestic and wild birds and some mammals have recently emerged and become widespread in Europe and North America, including across Canada, Central and South America, sub-Antarctic regions and Antarctica. Government authorities in Canada are currently responding to the outbreak of influenza A(H5N1) in farmed birds and wildlife across Canada.

Influenza A(H5N1) is a subtype of avian influenza virus that mainly infects birds, but has been identified in other animals and has caused rare and sporadic infections in humans.

Human cases of influenza A(H5N1) have primarily occurred due to zoonotic transmission through direct contact with infected birds (dead or alive) or contaminated environments. Human-to-human transmission is rare and there has been no evidence of sustained transmission between humans.

The virus mainly affects the respiratory tract but can also cause gastrointestinal or central nervous system manifestations. Infection may progress to severe illness and can be fatal.

Clinicians and front-line laboratory personnel are encouraged to follow the Protocol for Microbiological Investigations of Severe Acute Respiratory Infections (SARI) to facilitate the diagnosis of severe respiratory infection caused by pathogens with epidemic potential.

Antivirals used to treat influenza can be effective in reducing morbidity and mortality, especially if administered early in the course of illness. Prophylactic use of influenza-specific antivirals (pre and post exposure) may prevent illness. Seasonal influenza vaccines do not offer protection against influenza A(H5N1).

Human infections of influenza A(H5N1) are notifiable under the International Health Regulations (2005). Provincial and Territorial public health authorities are required to report confirmed and probable human cases of influenza A(H5N1), irrespective of illness symptoms or severity, to the Public Health Agency of Canada (PHAC) within 24 hours of their own notification, as per the Emerging Respiratory Pathogens and Severe Acute Respiratory Infection (SARI) case report form. PHAC is required to report any human case detected in Canada to the World Health Organization according to the International Health Regulations (2005) requirements and timelines.

For detailed recommendations on public health management and reporting requirements, consult the appropriate local, provincial, or territorial health authorities.