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Diseases / Meningococcal diseases

Meningococcal diseases

What is it?: 

In most countries, Neisseria meningitidis (the meningococcus) is recognized as a leading cause of meningitis and fulminant septicaemia and a significant public health problem. However, surveillance data from many countries, particularly in Asia, are incomplete or lacking and there is currently no reliable global burden estimate.1

N. meningitidis is a gram-negative diplococcal bacterium which causes disease only in humans. It is classified into 12 serogroups (A, B, C, 29E, H, I, K, L, W135, X, Y and Z) based on the structure of the polysaccharide capsule. The majority of invasive meningococcal infections are caused by organisms expressing one of the serogroup A, B, C, X, W135 or Y capsular polysaccharides.1 Based on the data from HK Centre for Health Protection, 66% of confirmed cases are caused by serogroup A, C, W135, Y in the period of 2013-2018.4

Neisseria species, which usually reside asymptomatically in the human nasopharynx, are easily transmitted to close contacts by respiratory droplets. In epidemic situations, nasopharyngeal carriage of potentially pathogenic N. meningitidis has been reported in 10%–25% of healthy adults.3

Clinical features: 

Symptoms of invasive meningococcal disease (IMD) usually occur 1–4 days after infection. Besides meningitis and septicaemia, meningococci occasionally cause arthritis, myocarditis, pericarditis and endophthalmitis.2

Signs and symptoms of IMD in infants and young children include fever, poor feeding, irritability, lethargy, nausea, vomiting, diarrhoea, photophobia and convulsions. The characteristic feature of meningococcal septicaemia is a hemorrhagic (petechial or purpuric) rash that does not blanch under pressure. Signs of meningitis in older children and adults include neck rigidity, photophobia and altered mental status, whereas in infants non-specific presentation with fever, poor feeding and lethargy is common.2

Most untreated cases of meningococcal meningitis and or septicaemia are fatal. Even with appropriate care up to 10% of patients die, typically within 24–48 hours of the onset of symptoms. Approximately 10% to 20% of survivors of meningococcal meningitis are left with permanent sequelae such as mental retardation, deafness, epilepsy, or other neurological disorders.3

Mode of transmission: 

The disease is mainly transmitted by direct contact through respiratory secretions from infected persons.2


WHO recommendations: In countries where the disease occurs less frequently (<2 cases per 100 000 population/year), meningococcal vaccination is recommended for defined risk groups, such as children and young adults residing in closed communities, e.g. boarding schools or military camps. Laboratory workers at risk of exposure to meningococci should also be vaccinated. Travellers to high-endemic areas should be vaccinated against the prevalent serogroup(s). In addition, meningococcal vaccination should be offered to all individuals suffering from immunodeficiency, including asplenia, terminal complement deficiencies, or advanced HIV infection.1


Other precautions:2

  • Keep hands clean. Wash hands with liquid soap and water properly especially when they are dirtied by respiratory secretions e.g. after sneezing. Clean hands with 70 – 80% alcohol-based handrub when they are not visibly soiled.
  • Cover nose and mouth while sneezing or coughing and dispose of nasal and mouth discharge in lidded rubbish bin.
  • Travellers to high risk areas should consult their doctor before the trip to determine the need for meningococcal vaccination.
  • Travellers returning from high risk areas should seek medical advice if they become ill. They should discuss their recent travel history with the doctor.

Meningococcal infection is a serious illness. Patients should be treated promptly with antibiotics. Close contacts would need to be placed under medical surveillance for early signs of disease and may be given preventive medications.2


1            World Health Organization. Meningococcal vaccines: WHO position paper. 2011.

2            Centre for Health Protection. Communicable diseases – Meningococcal Infection. 2020. (accessed 2 Feb2021).

3            World Health Organization. Meningococcal meningitis. 2020. (Accessed 2 Feb 2021).

4            Centre for Health Protection. Communicable Diseases Watch (2018); 15(12) [ONLINE]. Available at: (Accessed on 14 Aug 2019).