Human Health Issues related to Avian Influenza in Canada

1 Introduction

Avian Influenza is a contagious viral infection that can affect all species of birds (poultry, exotic and pet birds, and wild birds), although some species are more resistant to infection than others[1](1,2,3). Avian influenza viruses do not normally infect mammalian species; however humans and a few other species including pigs and felines can be infected, and in some instances the ability to transmit the avian virus from mammal to mammal has been observed. The documented history of avian influenza dates back to the last century when "fowl plague", now known as influenza, was first described in 1878. In 1955 Schafer demonstrated that fowl plague was a member of the influenza A virus group.(4) Since 1959, twenty-four epizootics (outbreaks) of highly pathogenic avian influenza caused by H5 or H7 strains have been documented worldwide(5). The majority of human cases linked to these avian influenza outbreaks have been identified since 1997.

The human health risks (actual and potential) associated with avian influenza are:

  • Direct infection of humans with the avian influenza virus
  • The emergence of a new pandemic strain of type A influenza

The purpose of this document is to provide recommendations for public health authorities and other stakeholders involved in the management of actual and potential human health issues related to domestic avian influenza outbreaks[2]. The management of the animal health component of the outbreak response is the responsibility of the Canadian Food Inspection Agency (CFIA) and is not addressed in this document. Wildlife management issues are also not addressed within the scope of this document. Information on avian influenza and outbreak management from an animal health perspective can be found on the CFIA website and on the OIE (World Organization for Animal Health) website (see section 2.4 below).

In this document the recommendations have been organized to align with certain components of the Canadian Pandemic Influenza Plan for the Health Sector, specifically: surveillance, public health measures, infection control, antivirals, and vaccine programs. This document is intended to serve as a reference for jurisdictions dealing with an outbreak of avian influenza. Other jurisdictions, not directly affected by the outbreak, are encouraged to refer to the sections of the Plan that correspond to the phases within the pandemic alert period (e.g., Canadian Phase 1.0, 2.0 or 3.0) as indicated by the epidemiological findings from the outbreak.

The objective of this document is to provide recommendations aimed at:

  • protecting individuals who are involved in the response to an outbreak of avian influenza
  • protecting individuals who have been exposed to the virus
  • controlling the outbreak in the human population[3] (if applicable), and
  • minimizing the risk of viral reassortment (i.e., mixing of genes from human and avian viruses)

Typically the first opportunity for public health intervention occurs when the virus causes illness in a domestic poultry flock. The recommendations in this document include prevention and control measures that should be implemented immediately, based on a risk assessment, to decrease the human health risk from a zoonotic infection and decrease pandemic potential. With respect to wild bird exposure, the recommendations in this document apply to individuals working with sick wild birds or participating in environmental clean-up of dead wild birds in areas/regions where highly pathogenic avian influenza (HPAI), for example H5N1 Asian strain, has been identified.

 

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