Invasive Meningococcal Disease

Invasive meningococcal disease (IMD) is caused by the bacteria Neisseria meningitidis. The bacteria can be classified into 12 serogroups Serogroups A, B, C, W and Y are the primary causes of meningococcal disease in Canada.

IMD is an uncommon, but serious disease spread through close contact with someone who has the bacteria in their nose and mouth (e.g., kissing or sharing items). IMD can lead to swelling of tissues surrounding the brain (meningitis) or bloodstream infection and causes complications such as hearing loss, amputations and death. Prompt medical attention and treatment are needed, as meningococcal infections can rapidly progress.

Signs and symptoms of IMD include a sudden onset of fever, headache, stiff neck, nausea, vomiting, sensitivity to light or drowsiness, rash (petechial or purpuric), and confusion or coma.

There has been increased IMD activity observed in Ontario in 2024, with 24 cases reported in the first half of the year (between January 1 and June 30, 2024). Of these 24 cases, 6 were serogroup B, 5 were serogroup C, 1 was serogroup E, 9 were serogroup W and 3 were serogroup Y. For information on the epidemiology of IMD in Ontario in 2023, please refer to the 2023 Enhanced Epidemiological Summary for IMD.

In Ontario, infants are immunized against meningococcal C and grade 7 students are offered a vaccine that protects against meningococcal A, C, Y and W .A vaccine to protect against meningococcal serogroup B disease is available for persons with underlying medical conditions that would them a higher risk of meningococcal disease.

To obtain or inquire about an immunization record, or for general immunization information, please contact your local public health unit.

For more information on historical IMD data, please refer to the Infectious Disease Trends in Ontario or the surveillance report on Diseases of Public Health Significance Cases.