At least 13 groups of Neisseria meningitidis have been identified and of these A, B, C, Y and W are the most likely to cause disease. Patterns of infection differ throughout the world. Although group A is the most common cause of meningococcal disease worldwide, in New Zealand, groups B and C are more likely to cause disease. Disease caused by groups A, Y and W occur infrequently in New Zealand.
Isolated outbreaks of meningococcal groups A and C have occurred in New Zealand: the last group A outbreak was in 1985/86 in Auckland, and the most recent group C outbreak was in Northland during 2012. During 1991-2007, a New Zealand-only strain of group B caused an epidemic. The epidemic mainly affected under-one year old Māori and Pacific infants and children aged 1 - 4 years of other ethnicities. The rate of meningococcal disease in 2014 was the lowest since 1990.
Vaccines that protect against meningococcal disease have been available since the 1970s but none protect against all the groups that cause disease. The current vaccines available in NZ protect against disease by groups A, C, W and Y.
The group B meningococcus is the most effective at evading the immune system, which makes it difficult to create a group B vaccine. New Zealand, Norway and Cuba have used specially manufactured vaccines against a single strain of meningococcal group B to reduce epidemic levels of disease in those countries. NZ used a single strain meningococcal B vaccine (MeNZBTM) between 2004 and 2008 to control an epidemic which has now waned. This vaccine is no longer available and there are currently no meningococcal group B vaccines available in New Zealand. However, a multiple strain meningococcal vaccine that includes group B vaccine has been added to the immunisation schedule in the UK and is approved in Australia.
How you get it
Meningococcal bacteria are commonly carried in the nose and throat, and do not usually cause disease. The bacteria can be transferred from person to person through contact with saliva, for example through intimate kissing. Saliva on shared drink bottles or pacifiers (dummies) may also have a limited role in passing the bacteria from one person to another. The bacteria may also be shared through droplets of saliva in the air from people coughing, sneezing or laughing.
It is not clear why in some vulnerable people the bacteria pass into their blood and brain to cause meningococcal disease (septicaemia or meningitis).
Initial symptoms are difficult to distinguish between viral or other bacterial infections, such as influenza. The symptoms usually start and progress quickly, often within 24 hours.
Infants may have:
Fever, cry, appear unsettled, feed poorly, vomit, be sleepy or hard to wake, dislike bright light or have a rash or spots. They may have a bulging fontanelle. Cold extremities and colour changes are early warning signs.
Older children, adolescents and adults may have:
Fever, malaise, nausea, vomiting, muscle aches and pains, drowsiness, headache, dislike of bright light, neck stiffness or have a rash or spots.
About 2/3 of cases will develop a rash that does not blanch (disappear) when pressed on. This type of rash is caused by bleeding under the skin and is a sign of advanced blood infection (septicaemia). About 75% of cases of invasive meningococcal disease have meningitis.
Prompt diagnosis, early administration of injected antibiotic to patients suspected of having meningococcal infection and immediate admission to the hospital may help to decrease the risk of permanent damage and death.
Being exposed to tobacco smoke, living in a crowded household or having another respiratory infection, e.g. influenza, can increase a person’s chances of carrying the bacteria.
Certain groups are also at increased risk of infection: household and other close contacts of someone with the disease (those who have been intimate or shared food and beverages), infants and children attending early childhood education or day care centres, and adolescents and young people at boarding school, living in hostels and university residences. Also health professionals and microbiology laboratory staff who are likely to be in close contact with patients or samples with meningococcal disease.
Some people with medical conditions that affect their immune system have an increased risk of infection, such as those without a functioning spleen, and those who are immunosuppressed from a disease or treatment of a disease.
Infants, children less than five years of age and adolescents, aged 15-19 years, have an increased risk of meningococcal disease. Māori or Pacific infants and young children have the greatest risk.
If meningococcal bacteria pass into the blood, the disease usually progresses very quickly. A person with meningococcal disease may develop:
- Meningitis (inflammation of the membranes around the brain)
- Septicaemia (blood infection)
- Pneumonia (lung inflammation)
- One to two people out of every ten who survive meningococcal disease have long term complications, such as extensive skin scarring, amputation of limbs and extremities, hearing loss, seizures or brain injury
- Even when the disease is identified and treated early, about 1 person in 10 will die
The risk of infection for household contacts of a person with the disease is highest during the first seven days and may persist for many weeks. Preventive antibiotics should be administered to close contacts as soon as possible, preferably within 24 hours of identification of the person with meningococcal disease.
Vaccination is recommended, but not funded, for young children and adolescents. Please refer to the IMAC factsheet on available meningococcal vaccines.
During an outbreak, a meningococcal immunisation programme may be commenced for those in the highest risk groups if a vaccine is available. Meningococcal conjugate vaccines reduce the number of people carrying N. meningitidis in the back of their throat thereby reducing the spread of the bacteria around the community. This contributes to ‘herd immunity’ while protecting the individual from invasive disease.
Complications of disease
Responses to meningococcal vaccines
|Responses to conjugate vaccines||
|Responses to polysaccharide vaccine||
As with any medicine, very rarely, severe allergic reactions occur following immunisation