Epidemiology
In 2018, one study reported the overall incidence of bacterial meningitis in Western countries as 0.7 to 0.9 per 100,000 people per year; incidence has decreased by 3% to 4% since the 1990s.[6] In the UK, 2594 cases of meningitis (due to any cause) were reported in children from 2004-2011. The overall incidence in African countries is 10-40 per 100,000 people per year.[6] The incidence of culture-proven bacterial meningitis in neonates is estimated at 0.3 per 1000 live births in developed countries.[7]
The introduction of widespread immunisation programmes in the UK and other developed countries, particularly the use of Haemophilus influenzae type b (Hib) and conjugate pneumococcal vaccines, has significantly reduced the overall incidence of bacterial meningitis in children.[2][3][6][8][9][10][11][12] In Europe, one study reported a decrease in the incidence of bacterial meningitis in children from 6.37 to 1.58 per 100,000 people per year between 1989-1993 and 2014-2019.[13] This decrease was most significant in preschool and school-aged children (5-15 years).[13] However, because of limited economic resources and poor living conditions, many developing countries continue to have high rates of disease.
In UK practice, there are low reporting rates of cases of bacterial meningitis, which makes collection of data difficult.
Risk factors
Infants who have not had their childhood vaccines are at high risk of contracting Haemophilus influenzae type b, pneumococcal, or meningococcal meningitis.[17]
Immunodeficiency, which can be congenital (e.g., hypogammaglobulinaemia, complement deficiency, common variable immunodeficiency, sickle cell disease) or acquired (e.g., asplenia or hyposplenia, use of immunosuppressive medication, HIV infection, cancer), increases the risk of bacterial meningitis.[5][20][21][22]
Congenital or acquired cranial structural defects may increase risk of bacterial meningitis.[5]
During the perinatal period, neonates are at increased risk of bacterial meningitis if:[24]
There is premature or prolonged (>18 hours) rupture of membranes
There is maternal colonisation with group B streptococcus
There is maternal chorioamnionitis
They are premature
They have low birth weight.
Exposure to infection within the household or close contact with another person who has meningitis increases the patient’s risk of bacterial meningitis.[5]
Infections such as sinusitis, pneumonia, mastoiditis, and otitis media increase the risk of meningitis.[5]
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