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Influenza (the "flu")

Influenza is a disease caused by the influenza virus. Symptoms of influenza include sudden onset of headache, chills and cough followed by a fever, appetite loss, muscle aches and tiredness. Influenza is one of the major causes of outbreaks in long-term care homes and daycares. For more information, see the health unit's fact sheet on "Cold vs. Flu".  

Influenza surveillance begins on September 1 each year and ends on August 31 of the following year. The majority of influenza cases occur between November and April.

The following graph shows the number of influenza cases in Simcoe Muskoka between 2000-01 and 2011-12. There are many factors that influence how many cases are reported to the health unit, as explained on the Infectious Diseases page.  There have been between 35 and 333 influenza cases every season since 1999-00.

The following graph shows the incidence rate of influenza in Simcoe Muskoka and Ontario between 1999-00 and 2011-12. The Simcoe Muskoka rate was similar to the Ontario rate until 2003-04 when it climbed higher than the Ontario rate for a few years. There is a lot of variability in both rates, which means that there are many peaks and valleys and it is difficult to determine whether an increase is significant or whether it is within the expected range for this disease. This is also because there are so many factors that affect the number of reported influenza cases.