Meningitis is an infection of the three membranes (called meninges) covering the brain and the spinal column. Meningitis can be caused by both bacteria (such as Haemophilus influenzae type B) and viruses (such as herpes simplex). Symptoms of meningitis include fever, intense headache, nausea and often vomiting. Newborns and elderly people are vulnerable to infection because their immune systems may be weaker. People with head injuries are also susceptible to infection.
Encephalitis is the inflammation of the brain. It can be caused by bacteria, such as those that cause meningitis, or viruses (e.g. West Nile virus). Encephalitis is often a complication of other diseases such as syphilis.
For more information, see the health unit's fact sheet on encephalitis and meningitis.
The following graph shows the number of encephalitis and meningitis cases in Simcoe Muskoka between 2000 and 2015. There have been between 11 and 44 cases of encephalitis/meningitis reported every year in Simcoe Muskoka since 2000. In 2015, 44 cases were reported in Simcoe Muskoka.
The following graph shows the incidence rate of encephalitis and meningitis in Simcoe Muskoka and Ontario between 2000 and 2015. In 2015, the Simcoe Muskoka rate was 8.0 cases per 100,000 population and the Ontario rate was 5.0 cases per 100,000 population.
There is some variability in the Simcoe Muskoka incidence rate, which means that there are 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. There is less variability in the Ontario rate because it is based on larger numbers of cases.
There are many factors that influence how many cases are reported to the health unit, as explained on the Infectious Diseases page.
Certain cases of encephalitis and meningitis are grouped together for surveillance because they can be difficult to clinically differentiate at the early stages of disease onset. The data and figures presented on this page include meningitis and encephalitis cases caused by bacteria or viruses that are not reportable as any other disease. For example, if West Nile virus is detected as the infectious agent responsible for encephalitis, then this is reported as a case of West Nile virus and not encephalitis. Meningitis caused by the bacteria Neisseria meningitidis is reported as invasive meningococcal disease and is not included in these graphs.
Provincial definitions classify cases as confirmed or probable based on clinical and/or laboratory diagnostic criteria. The provincial case definition for encephalitis/meningitis changed in April 2009 to include a definition for probable cases whereas before there was no such classification. The definitions of confirmed and probable cases from 2009 onwards are comparable to confirmed cases before 2009.