Epidemiology

Meningococcal disease is seen in all countries:

• large epidemics are seen in the ‘meningitis belt’ of the sub Saharan Africa especially towards the end of the dry, dusty season when the disease spreads rapidly. Majority is due to serogroup A, but W135 and X have been recorded in recent outbreaks.
• large epidemics of meningococcal disease have been reported in the annual Hajj pilgrimage to Mecca in Saudi Arabia. Since 2002 evidence of receipt of quadrivalent vaccine (serogroups A, C, Y, W135) became an entry requirement to Saudi Arabia (1)

Meningococcal infection is most often seen in closed crowded communities such as army barracks or schools, and is the most common cause of bacterial meningitis in the UK. Poor socioeconomic state and race - afrocarribean - also predispose to this infection.

• a slight declined in the incidence of meningococcal disease has been observed in recent years - average annual incidence was 2.05 per 100,000 population between 2006/2007 to 2009/2010 (88% were due to serogroup B infection) (2)
• 2962 cases of meningococcal disease were notified in 1998/9
• two national outbreaks due to W135 (previously rare in the UK) was reported in 2000 and 2001 following Hajj pilgrimages (2)
• peak incidence of meningococcal disease is in the winter months
• about half of the cases of meningococcal disease in UK are in children under the age of four (3)
• on average a GP can expect to see one to two cases of meningococcal disease in his or her career in primary care (3)
• Meningocococcal group B accounts for most cases
  • as no vaccine is currently licensed against serogroup B meningococcus, this pathogen is now the most common cause of bacterial meningitis (and septicaemia) in children and young people aged 3 months or older
  • most N meningitidis colonisations are asymptomatic, but occasionally the organism invades the bloodstream to cause disease. Meningococcal disease most commonly presents as bacterial meningitis (15% of cases) or septicaemia (25% of cases), or as a combination of the two syndromes (60% of cases). Meningococcal disease is the leading infectious cause of death in early childhood
• causes less than 10% of meningitis in people older than 45 years
• vulnerability is confered possibly by complement deficiency - C5,6,7,8, and perhaps 9, also C4b, properdin - and also by the asplenic state
• meningitis is the commonest presentation - mortality is 3-5%
• features of septicaemia are predominant in 15-20% of cases - mortality is 15-20%

Reference:

1. Department of Health (DH) 2010. Immunisation against infectious disease - "The Green Book". Chapter 22- Meningococcal
2. Health Protection Agency (HPA) 2011. Guidance for public health management of meningococcal disease in the UK.
3. Hart CA, Thomson AP. Meningococcal disease and its management in children. BMJ. 2006;333(7570):685-90
4. NICE (June 2010). Bacterial meningitis and meningococcal septicaemia Management of bacterial meningitis and meningococcal septicaemia in children and young people younger than 16 years in primary and secondary care
5. Replacement chapter for "Immunisation Against Infectious Disease" 1996 PL CMO (99)4, PL CON (99)8, PL CPHO (99)3