How is IMD transmitted?
It is believed that 10% to 20% of the population carries N. meningitidis in their throat at any given time. The carriage rate may be higher in epidemic situations. 1
5-10% of adults are asymptomatic nasopharyngeal carriers of strains of N. meningitidis, most of which are not pathogenic. For the majority of people, carriage is an immunizing process that results in a systemic, serogroup-specific protective antibody response. 2 3
Direct contact with a carrier’s oropharyngeal secretions (in activities such as kissing, sneezing or coughing on someone for example) spreads the disease.
Also crowded living conditions (for instance students in dormitories, military recruits or Hajj pilgrims) facilitate the spread of the disease. 1 2 4
The average incubation period for IMD is 4 days, but can range between 2 and 10 days. 1
- World Health Organization (WHO). Meningococcal meningitis. Fact sheet No.141 (Updated November 2015). Available at: http://www.who.int/mediacentre/factsheets/fs141/en/. Last accessed December 2016
- Centers for Disease Control and Prevention. Manual for the surveillance of vaccine-preventable diseases. Chapter 8: Meningococcal Disease. Centers for Disease Control and Prevention, Atlanta, GA, 2008 available at https://www.cdc.gov/vaccines/pubs/surv-manual/chpt08-mening.html. Last accessed December 2016
- Rosenstein NE et al. Meningococcal disease. N Engl J Med 2001;344(18):1378–88
- Dull PM, et al., Neisseria meningitidis Serogroup W-135 Carriage among US Travelers to the 2001 Hajj, J Infect Dis. 2005;1919:33-39