At least 12 groups have been identified, including groups A, B, C, X, Y and W (previously called W-135). The pattern of disease caused by each group varies by time and country or geographical areas. In New Zealand over 2014–2017, meningococcal group B caused around two-thirds of meningococcal disease each year, group C almost one-third and groups Y or W the remaining few cases. However, in 2018 group B decreased as the cause of around half of cases. Group C also decreased significantly and disease caused by meningococcal groups Y and W increased to cause almost half the number of cases. Group W disease included cases caused by a very virulent sequence type of meningococcal group W (ST-11). Meningococcal group A rarely causes disease in NZ.
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. Isolated outbreaks of meningococcal groups A and C have occurred in New Zealand: the last group A outbreak was in 1985/86 in Auckland. Northland experienced an outbreak of meningococcal group C disease during 2012. Then in 2018, Northland experienced a disproportionately high number of meningococcal diseases cases (7.4 cases per 100,000 people) compared with New Zealand overall (2.5 cases per 100,000). Group W was the predominant cause of meningococcal disease in Northland in 2018.
How you get it
Meningococcal bacteria are commonly carried in the nose and throat, and do not usually cause disease. Carriage rates are highest in older teenagers and young adults. The bacteria can be transferred from person to person through contact with saliva, e.g. intimate kissing. In rare cases, the bacteria can invade and rapidly lead to severe disease. The underlying reasons for why invasion occurs in some individuals are not well understood.
Who is at risk?
In New Zealand, infants and children aged under 5 years and adolescents aged 15–19 years have an increased risk of meningococcal disease. Māori, particularly infants aged under 1 year, and Pacific peoples have a higher risk of meningococcal disease than other ethnic groups.
What increases the risks?
- Exposure to tobacco smoke, binge drinking, or having another respiratory infection, e.g. influenza.
- Living in close proximity to others, e.g. in a crowded household, at boarding school, in university halls of residence, or in long-term institutional care.
- Being in a household or other close contact of someone carrying the bacteria or with the disease, e.g. those who have been intimate, or infants and children attending an early childhood education centre.
- Having a medical condition or receiving treatment that affects the immune system, e.g. the person has had their spleen removed, or taking disease modifying immunosuppressive medication.
- Age and ethnicity.
The initial symptoms are difficult to distinguish from other infectious illnesses, particularly flu-like illnesses. Symptoms usually progress quickly to a severe illness, often within 24 hours.
- Infants may have: a more gradual onset than adults, 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.
- Older children and adults may have: a fever, malaise, nausea, vomiting, muscle aches and pains, drowsiness, headache, dislike of bright light, neck stiffness, or have a rash or spots.
- Individuals may also present with atypical symptoms, including gastrointestinal symptoms, pneumonia, septic arthritis, endocarditis, epiglottitis or supraglottitis.
Almost 80% of cases will develop a rash that does not blanch (become pale/go white) when pressed on. This type of rash is often a late sign of infection.
What are the risks?
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 infection)
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 1–2 people in 10 will die.
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.
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.
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.
Vaccines that protect against meningococcal disease have been available since the 1970s but none protect against all the groups that cause disease. There have been vaccines against the groups A, C, Y and W for more than 20 years but it has taken much longer to develop vaccines that protect against the different types of meningococcal group B. Please refer to the IMAC factsheet on available meningococcal vaccines.
Complications of disease
Responses to meningococcal vaccines
Menactra®, NeisVac-C®, Nimenrix®
As with any medicine, very rarely, severe allergic reactions occur following immunisation
- Baker MF, et al. Household crowding a major risk factor for epidemic meningococcal disease in Auckland children. Pediatr Infect Dis J. 2000;19:983-90.
- Harrison L, et al. Meningococcal capsular group A, C, W, and Y conjugate vaccines. In: Plotkin S, Orenstein W, Offit P, Edwards K, editors. Plotkin's Vaccines. 7th ed. Philadelphia: Elsevier; 2018. p. 619-43.
- Institute of Environmental Science and Research Ltd. Notifiable diseases in New Zealand: Annual report 2016. Porirua: Institute of Environmental Science and Research Ltd (ESR); 2017. Report No.: FW17028.
- Institute of Environmental Science and Research Ltd. New Zealand public health Surveillance report March 2018. Wellington: Institute of Environmental Science and Research Ltd (ESR); 2018.
- Institute of Environmental Science and Research Ltd. Invasive meningococcal disease report 3 April 2019. Porirua: Institute of Environmental Science and Research Ltd (ESR); 2019.
- Lopez L, Sherwood J. The epidemiology of meningococcal disease in New Zealand 2013. Wellington: Institute of Environmental Science and Research Ltd (ESR); 2014. Report No.: FW14023.
- McCall BJ, et al. Risk factors for invasive meningococcal disease in southern Queensland, 2000–2001. Intern Med J. 2004;34:464-8.
- Ministry of Health. 2012, last update May 2018. Communicable Disease Control Manual 2012. Wellington: Ministry of Health.
- Ministry of Health. Immunisation handbook 2017 2nd Edition [Internet]. Wellington: Ministry of Health; 2017 [cited 2018 August 24]. Available from: https://www.health.govt.nz/publication/immunisation-handbook-2017.
- Musher DM. How contagious are common respiratory tract infections? N Engl J Med. 2003;348:1256-66.
- Nokleby H. Vaccination and anaphylaxis. Curr Allergy Asthma Rep. 2006;6(1):9-13.
- Orr HJ, Gray SJ, Macdonald M, Stuart JM. Saliva and meningococcal transmission. Emerg Infect Dis. 2003;9(10):1314-5.
- Peterson ME, Mile R, Li Y, Nair H, Kyaw MH. Meningococcal carriage in high-risk settings: A systematic review. Int J Infect Dis. 2018;73:109-17.
- Stephens DS, at al. Epidemic meningitis, meningococcaemia, and Neisseria meningitidis. Lancet. 2007;369:2196-210.
- Virji M. Pathogenic Neisseriae: surface modulation, pathogenesis and infection control. Nat Rev Microbiol. 2009;7(4):274-86.
- Welsby PD, Golledge CL. Meningococcal meningitis: A diagnosis not to be missed. Br Med J. 1990;300(6733):1150-1.
- World Health Organization. The immunological basis for immunization series: Module 15: Meningococcal disease. Geneva: World Health Organization, 2010.
- Yung AP, McDonald MI. Early clinical clues to meningococcaemia. Med J Aust. 2003;178(3):134-7.