Invasive Meningococcal Disease

For Health Professionals

Invasive meningococcal disease (IMD) is an acute and serious communicable disease caused by the bacterium Neisseria meningitidis, resulting in meningitis, septicemia (meningococcemia) or both. The National Advisory Committee on Immunization (NACI) recommends routine immunization against meningococcal disease and the Committee to Advise on Tropical Medicine and Travel (CATMAT) recommends immunization before travel to high risk meningococcal destinations.

Agent of disease

Invasive meningococcal disease (IMD) is caused by the gram-negative bacterium Neisseria meningitidis (meningococcus). Meningococci can be classified based on the immunologic reactivity of the polysaccharide capsule into 12 different serogroups, of which five (A, B, C, W-135 and Y) are associated most frequently with IMD in Canada and around the globe, with incidence varying by the meningococcal serogroup.

Reservoir

Humans.

Spectrum of Clinical Illness

The most common form of meningococcal infection is the carrier state, where colonization occurs in up to 10% of healthy individuals. A person may remain a carrier for up to six months and remain asymptomatic.

In a small proportion of carriers, the bacterium invades the blood or meninges leading to invasive meningococcal disease. Symptoms occur 2 to 10 days (usually 3 to 4 days) after exposure.

Symptoms include:

the sudden development of fever
drowsiness
irritability or agitation
intense headache
nausea
vomiting
stiff neck and
photophobia

Most commonly, invasive disease results in meningitis and/ or septicemia, in addition to a characteristic non-blanching petechial or purpuric rash.

Severe cases can result in delirium and coma and, if untreated, toxic shock and death. Overall mortality is approximately 10%, and up to a third of survivors have long term sequelae which include hearing loss, neurologic disabilities, and digit or limb amputations.

Photos of Clinical Manifestations of IMD.

4 month old infant with gangrene of hands and lower extremities due to meningococcemia

Source: Centers for Disease Control and Prevention ©

Lower extremities showing meningococcemia

Adolescent female with marked purpura of the left foot

Transmission

Meningococcal disease is characterized by a short incubation period (2 to 10 days, usually 3 to 4 days). It is transmitted from an infected person (including carriers) to another person through close, direct contact such as kissing, coughing and sneezing. Transmission can also occur through saliva when sharing items such as cigarettes, lipstick, food and drinks, etc.

Bacterial eradication from the nose and throat usually occurs within 24 hours of appropriate antimicrobial therapy.

Disease Distribution (Global)

Meningococcal disease occurs sporadically worldwide and in focal epidemics. For the global distribution of the disease, please check the World Health Organization (WHO) fact sheet.

Current meningococcal disease outbreak information is available from the WHO Global Alert and Response (GAR) - Meningococcal disease.

Risk Factors

Risk factors for the development of IMD include:

complement, properdin or factor D deficiencies
functional or anatomic asplenia (including sickle cell disease)
certain genetic risk factors
household exposure to an infected person
concurrent respiratory tract infection
recent influenza
household crowding and
active and passive smoking

Persons with HIV infection may be at increased risk for meningococcal disease, especially if HIV is congenitally acquired.

Prevention and Control

Invasive meningococcal disease due to infection by serogroups A, B, C, W-135, and Y can be prevented by immunization.

Routine use of monovalent meningococcal vaccine against serogroup C is recommended by NACI for all infants as a part of the routine immunization schedule.

A booster dose of either monovalent serogroup C vaccine or quadrivalent vaccine (for protection against serogroups A, C, W-135, and Y) is recommended around the age of 12 years. Additionally, quadrivalent vaccine is recommended for selected individuals at increased risk of acquiring infection.

For specific recommendations about meningococcal vaccines and their use, please refer to the most recent Canadian Immunization Guide as well as NACI statements on invasive meningococcal disease.

For further information on prevention and control measures, please see the IMD Disease prevention and Control Guidelines.

Epidemiology of Invasive Meningococcal Disease in Canada

Invasive meningococcal disease is endemic in Canada. The incidence rate varies considerably amongst serogroups, age groups, geographic locations and time.

The implementation of immunization programs began in 2002 with the introduction of conjugate meningococcal C vaccine, and has varied by province/territory.

As depicted in Figure 1, from 1985 to 2011 the overall incidence of IMD ranged between 0.4 to 1.6 cases per 100,000 population, showing periods of increased activity approximately every 10 to 15 years with no consistent pattern.

Between 2006 and 2011, an average of 196 cases of IMD was reported annually in Canada, with an average incidence of 0.58 cases per 100,000 population. During this time period, incidence rates were highest among infants less than one year of age (average 7.35 cases per 100,000), followed by 1 to 4 year olds (1.89), and 15 to 19 year olds (1.17). Although IMD is rare, cases are reported year round with peaks in the winter season.

In Canada, serogroups B, C, W-135 and Y are the most commonly reported serogroups. Between 2006 and 2011, incidence rates of serogroup B were highest (0.33 cases per 100,000) for all meningococcal isolates.

With the introduction of meningococcal C immunization programs, not unexpectedly, the incidence of serogroup C has decreased significantly from 0.13 in 2006 to 0.01 in 2011.

While the incidence of serogroup B remains predominant, diseases of serogroup W-135 and Y have stabilized at relatively lower incidence rates of 0.03 (range: 0.02 to 0.04) and 0.10 (range: 0.08-0.11), respectively.

IMD caused by serogroup B has tended to affect people in younger age (median age 16 years) whereas serogroups C, W-135 and Y have tended to affect people in older age groups (median age 43, 38 and 47 years, respectively).

The case-fatality ratio for IMD (CFR) was 8.1% from 2006 and 2011. CFRs differed by serogroup, with serogroup C having the highest CFR at 14.5% and serogroup B having the lowest CFR at 5.5%.

More detailed information on current epidemiology of IMD in Canada can be found in the Canadian Communicable Disease Report.

Figure 1. Number of reported IMD cases and overall incidence rates in Canada, 1985-2011^*

Text Equivalent - Figure 1

Number of reported IMD cases and overall incidence rates in Canada, 1985-2011* In Canada, the annual number of invasive meningococcal disease cases increased from 111 to 447 cases between 1985 and 1990. The number of cases then decreased down to 264 in 1996 and increased again to a peak of 366 in 2001. Since 2002, case numbers have stabilized at a relatively low range between 154 and 234.

In Canada, the annual incidence rate of invasive meningococcal disease increased from 0.43 to 1.61 cases per 100,000 population between 1985 and 1990. It then decreased down to 0.89 cases per 100,000 in 1996 and again to a peak of 1.18 per 100,000 in 2001. Since 2002, incidence has stabilized at a relatively low range between 0.45 and 0.75 cases per 100,000.

*Case data obtained from the National Enhanced Invasive Meningococcal Disease Surveillance System. Population data obtained from Statistics Canada July 1st annual estimates. .

Figure 2. Serogroup specific IMD incidence rates in Canada, 2006-2011.

Text Equivalent - Figure 2

Serogroup specific IMD incidence rates in Canada, 2006-2011*

In Canada, serogroups B, C, W-135 and Y are most commonly reported types. Between 2006 and 2011, incidence rates of serogroup B were highest (0.33 cases per 100,000) among all serogroups. With the introduction of MenC childhood immunization programs in 2002, not unexpectedly, the incidence of serogroup C has decreased significantly from 0.13 in 2006 to 0.01 in 2011. While the incidence of serogroup B remains predominant, diseases of serogroup W-135 and Y stabilize at relatively lower incidence rates of 0.03 (range: 0.02 to 0.04) and 0.10 (range: 0.08-0.11), respectively. *Case data obtained from the National Enhanced Invasive Meningococcal Disease Surveillance System. Population data obtained from Statistics Canada July 1st annual estimates.

Invasive Meningococcal Disease Surveillance in Canada

Health professionals in Canada play a critical role in identifying and reporting cases of invasive meningococcal disease. See the Surveillance section for more information on IMD surveillance in Canada.