The Influenza section provides the general public and health professionals with easy access to a wide variety of information about influenza (flu). Here you'll find links to general information about seasonal influenza (flu), avian influenza (“bird flu”), Canada's pandemic influenza plan and influenza surveillance. Health Professionals can also use this section to access the Emerging Respiratory Infections site.
What is the difference between seasonal, avian and pandemic flu?
(Chart - available in multiple languages)
Human influenza, or the flu, is a respiratory infection caused by the influenza virus. Strains circulate every year, making people sick. Influenza typically starts with a headache, chills and cough, followed rapidly by fever, loss of appetite, muscle aches and fatigue, running nose, sneezing, watery eyes and throat irritation. Nausea, vomiting and diarrhea may also occur, especially in children.
Most people will recover from influenza within a week or ten days, but some - including those over 65 and adults and children with chronic conditions, such as diabetes and cancer - are at greater risk of more severe complications, such as pneumonia. Between 4 000 and 8 000 Canadians can die of influenza and its complications annually, depending on the severity of the season.
Birds and other animals, including pigs, also contract and transmitinfluenza. Wild birds, in particular, are natural carriers of influenza A viruses. They have carried animal influenza viruses, with no apparent harm, for centuries. Migratory waterfowl (ducks, geese) are known to carry viruses of the H5 and H7 strains or subtypes. These viruses are usually in the low pathogenic form - in other words, they aren't as deadly to birds as highly pathogenic strains.
Currently, avian influenza H5N1 is circulating in Asia, Europe, and Africa, infecting many poultry populations and some humans. This strain is highly pathogenic, or highly deadly to birds, and has infected a limited number of people. There is no evidence this virus is transmitted from person to person.
People are exposed to different strains of the influenza virus many times during their lives. Even though the virus changes, their previous bouts of influenza may offer some protection against infection caused by a similar strain of the virus. However, three to four times each century, for unknown reasons, a radical change takes place in the influenza A virus causing a new strain to emerge.
To see where the flu is active in Canada, visit FluWatch. FluWatch produces weekly surveillance reports from October to May in collaboration with provincial and territorial ministries of health, participating laboratories, the College of Family Physicians of Canada and sentinel doctors.
The information provided on this site is directed primarily to health/public health professionals and aims to provide guidelines and standards for the detection, rapid response and control of outbreaks due to an emerging respiratory pathogen.
The National Advisory Committee on Immunization (NACI) provides the Public Health Agency of Canada with ongoing and timely medical, scientific, and public health advice relating to immunization. Past and present annual statements on Influenza vaccination can be accessed on the NACI web site.