Epidemiology

Incidence of acute bacterial meningitis in the developed world is estimated to be around 1 to 2 per 100,000 people with an estimated mortality of 10%–20% (1).

• in underdeveloped countries the figure may be 10 times as high as the western world
  • in the Sahel region of Africa incidence can reach 1,000 cases per 100,000 (2)
• it is one of the top 10 causes of infection related death worldwide
• 30 – 50% of survivors will experience permanent neurological sequelae (1)

Britain in 1993 was still in an epidemic of meningitis. In 1992, 1,138 cases of meningitis, with 169 deaths, and 277 cases of septicaemia were reported. However, the case fatality rate has remained unchanged for 30 years. In 66% of cases the offending organism was group B Neisseria meningitidis, for which there is no vaccine. Benzylpenicillin is given by GPs before transfer to the hospital in less than 30% of cases.

Introduction and widespread use of conjugate vaccines have resulted in a significant reduction in incidence over the last few decades

A 56% reduction in invasive pneumococcal disease (IPD) among adults has been reported since the introduction of the PCV7 into the routine infant schedule and its replacement by PCV13 in April 2010 (3)

• majority of reduction is seen in children under 1 year
• globally, reduction in meningitis-associated mortality was largely seen in children under five years of age - a 43% decrease in neonates and a 54% reduction in children aged between 1 and 59 month
  • in those over 5 years, reported number of deaths only reduced by 2·7%, from 165,900 to 161,500 between 1990 and 2013 (2).

Epidemics occur with meningococcus only. There is a meningitis belt in Africa in which there have been 39,000 cases and 5,300 deaths per year over last 10 years.

Reference:

• (1) Viallon A, Botelho-Nevers E, Zeni F. Clinical decision rules for acute bacterial meningitis: current insights. Open Access Emerg Med. 2016;8:7-16.
• (2) McGill F et al. Acute bacterial meningitis in adults. Lancet. 2016;388(10063):3036-3047.
• (3) Waight PA, Andrews NJ, Ladhani SN, et al.Effect of the 13-valent pneumococcal conjugate vaccine on invasive pneumococcal disease in England and Wales 4 years after its introduction: an observational cohort study. Lancet Infect Dis 2015;15:535–43. doi:10.1016/S1473-3099(15)70044-7.