Meningitis causes hundreds of thousands of deaths globally each year. Although viral meningitis is more common than bacterial meningitis, bacterial meningitis is more likely to be associated with a poor prognosis, higher mortality, and requires prompt recognition and treatment.[5]GBD 2019 Meningitis Antimicrobial Resistance Collaborators. Global, regional, and national burden of meningitis and its aetiologies, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet Neurol. 2023 Aug;22(8):685-711.
https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(23)00195-3/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/37479374?tool=bestpractice.com
[6]Mount HR, Boyle SD. Aseptic and bacterial meningitis: evaluation, treatment, and prevention. Am Fam Physician. 2017 Sep 1;96(5):314-22.
https://www.aafp.org/pubs/afp/issues/2017/0901/p314.html
http://www.ncbi.nlm.nih.gov/pubmed/28925647?tool=bestpractice.com
The Global Burden of Disease Study estimated in 2019 there were 236,000 deaths globally due to meningitis.[5]GBD 2019 Meningitis Antimicrobial Resistance Collaborators. Global, regional, and national burden of meningitis and its aetiologies, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet Neurol. 2023 Aug;22(8):685-711.
https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(23)00195-3/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/37479374?tool=bestpractice.com
The most common bacterial meningitis etiologies in all regions globally were Streptococcus pneumoniae, Neisseria meningitidis (or meningococcus), Haemophilus influenzae, and Streptococcus agalactiae (group B streptococcus). These bacteria are responsible for more than half the deaths from meningitis globally. S pneumoniae was the leading cause of all age meningitis deaths at 18.1%. Although vaccines can prevent most infections due to these three etiologies, not all countries have fully immunized their populations.[5]GBD 2019 Meningitis Antimicrobial Resistance Collaborators. Global, regional, and national burden of meningitis and its aetiologies, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet Neurol. 2023 Aug;22(8):685-711.
https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(23)00195-3/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/37479374?tool=bestpractice.com
[7]World Health Organization. Meningitis. Apr 2025 [internet publication].
https://www.who.int/news-room/fact-sheets/detail/meningitis#:~:text=These%20bacteria%20are%20responsible%20for,also%20important%20causes%20of%20meningitis
The epidemiology of bacterial meningitis has changed due to widespread immunization programs, including the introduction of protein-polysaccharide conjugate vaccines. In countries with universal Haemophilus influenzae type b (Hib) immunization programs, the incidence of Hib meningitis has declined by 95% to 99%.[8]Brouwer MC, van de Beek D. Epidemiology of community-acquired bacterial meningitis. Curr Opin Infect Dis. 2018 Feb;31(1):78-84.
http://www.ncbi.nlm.nih.gov/pubmed/29176349?tool=bestpractice.com
[9]Sáez-Llorens X, McCracken GH Jr. Bacterial meningitis in children. Lancet. 2003 Jun 21;361(9375):2139-48.
http://www.ncbi.nlm.nih.gov/pubmed/12826449?tool=bestpractice.com
Pneumococcal meningitis
S pneumoniae continues to be the leading cause of invasive bacterial meningitis globally. In the US, it accounts for approximately 2000 cases per year.[10]Centers for Disease Control and Prevention. Epidemiology and prevention of vaccine-preventable diseases: chapter 17: pneumococcal disease. May 2024 [internet publication].
https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-17-pneumococcal-disease.html#:~:text=Pneumococci%20cause%20more%20than%2050%%20of%20all,cases%20of%20pneumococcal%20meningitis%20occurring%20each%20year
However, since the 2000 introduction of the heptavalent pneumococcal vaccine in the US, the overall rates of pneumococcal meningitis have declined significantly from 0.8 in 100,000 in 1997 to 0.3 in 100,000 in 2010. A further decline in pneumococcal meningitis, particularly in patients ages 2 years or less, was recorded subsequent to the introduction of the 10- and 13-valent vaccines in 2010.[11]Castelblanco RL, Lee M, Hasbun R. Epidemiology of bacterial meningitis in the USA from 1997 to 2010: a population-based observational study. Lancet Infect Dis. 2014 Sep;14(9):813-9.
http://www.ncbi.nlm.nih.gov/pubmed/25104307?tool=bestpractice.com
[12]Hsu HE, Shutt KA, Moore MR, et al. Effect of pneumococcal conjugate vaccine on pneumococcal meningitis. N Engl J Med. 2009 Jan 15;360(3):244-56.
https://www.nejm.org/doi/full/10.1056/NEJMoa0800836
http://www.ncbi.nlm.nih.gov/pubmed/19144940?tool=bestpractice.com
[13]Olarte L, Barson WJ, Barson RM, et al. Impact of the 13-valent pneumococcal conjugate vaccine on pneumococcal meningitis in US children. Clin Infect Dis. 2015 Sep 1;61(5):767-75.
https://academic.oup.com/cid/article/61/5/767/303936
http://www.ncbi.nlm.nih.gov/pubmed/25972022?tool=bestpractice.com
Meningococcal meningitis
N meningitidis, causing meningococcal meningitis, is the pathogen with the most potential to produce large epidemics. There are 12 serogroups of N meningitidis that have been identified, 6 of which (A, B, C, W, X, and Y) can lead to mass outbreaks of the disease.[7]World Health Organization. Meningitis. Apr 2025 [internet publication].
https://www.who.int/news-room/fact-sheets/detail/meningitis#:~:text=These%20bacteria%20are%20responsible%20for,also%20important%20causes%20of%20meningitis
The highest incidence of meningococcal disease is found in the “meningitis belt” of sub-Saharan Africa, where rates can reach 1000 cases per 100,000 population.[14]Centers for Disease Control and Prevention. Meningococcal disease: meningococcal disease in other countries. Feb 2024 [internet publication].
https://www.cdc.gov/meningococcal/php/global/index.html
The incidence in African countries is 10-40 in 100,000 people per year. The higher rates of infection reflect the epidemics of meningococcal meningitis that occur throughout the African meningitis belt during the dry season.[8]Brouwer MC, van de Beek D. Epidemiology of community-acquired bacterial meningitis. Curr Opin Infect Dis. 2018 Feb;31(1):78-84.
http://www.ncbi.nlm.nih.gov/pubmed/29176349?tool=bestpractice.com
[15]Paireau J, Chen A, Broutin H, et al. Seasonal dynamics of bacterial meningitis: a time-series analysis. Lancet Glob Health. 2016 Jun;4(6):e370-7.
https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(16)30064-X/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/27198841?tool=bestpractice.com
[16]van Kessel F, van den Ende C, Oordt-Speets AM, et al. Outbreaks of meningococcal meningitis in non-African countries over the last 50 years: a systematic review. J Glob Health. 2019 Jun;9(1):010411.
https://jogh.org/documents/issue201901/jogh-09-010411.pdf
http://www.ncbi.nlm.nih.gov/pubmed/30937163?tool=bestpractice.com
Globally, of the top 10 countries with the greatest absolute number of meningitis deaths, only four are located outside the African meningitis belt (India, Pakistan, Afghanistan, China).[17]GBD 2016 Meningitis Collaborators. Global, regional, and national burden of meningitis, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet Neurol. 2018 Dec;17(12):1061-82.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234314
http://www.ncbi.nlm.nih.gov/pubmed/30507391?tool=bestpractice.com
Most outbreaks of N meningitidis outside Africa are caused by meningococcal serogroups B and C, with emergence of serogroup W135 since 2012.[16]van Kessel F, van den Ende C, Oordt-Speets AM, et al. Outbreaks of meningococcal meningitis in non-African countries over the last 50 years: a systematic review. J Glob Health. 2019 Jun;9(1):010411.
https://jogh.org/documents/issue201901/jogh-09-010411.pdf
http://www.ncbi.nlm.nih.gov/pubmed/30937163?tool=bestpractice.com
In Africa, serogroups A, C, and W account for substantial proportions of meningococcal disease.[18]Peterson ME, Li Y, Bita A, et al. Meningococcal serogroups and surveillance: a systematic review and survey. J Glob Health. 2019 Jun;9(1):010409.
https://jogh.org/documents/issue201901/jogh-09-010409.pdf
http://www.ncbi.nlm.nih.gov/pubmed/30603079?tool=bestpractice.com
Meningococcal vaccines are available for serogroups A, B, C, W, and Y.
In the US, the overall rate of meningococcal disease has been declining since the 1990s, with further declines linked to the introduction of the quadrivalent meningococcal conjugate vaccine in 2005.[19]Thigpen MC, Whitney CG, Messonnier NE, et al. Bacterial meningitis in the United States, 1998-2007. N Engl J Med. 2011 May 26;364(21):2016-25.
https://www.nejm.org/doi/10.1056/NEJMoa1005384
http://www.ncbi.nlm.nih.gov/pubmed/21612470?tool=bestpractice.com
A decrease in incidence was also witnessed in other countries with conjugated vaccine uptake. In the UK, serogroup C vaccination was implemented in 1998 and serogroup B vaccination in 2015.[20]Ladhani SN, Ramsay M, Borrow R, et al. Enter B and W: two new meningococcal vaccine programmes launched. Arch Dis Child. 2016 Jan;101(1):91-5.
https://adc.bmj.com/content/101/1/91.long
http://www.ncbi.nlm.nih.gov/pubmed/26672098?tool=bestpractice.com
Much of the beneficial effect of these vaccines was achieved by herd immunity.[21]Whittaker R, Dias JG, Ramliden M, et al. The epidemiology of invasive meningococcal disease in EU/EEA countries, 2004-2014. Vaccine. 2017 Apr 11;35(16):2034-41.
https://www.sciencedirect.com/science/article/pii/S0264410X17303134?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/28314560?tool=bestpractice.com
However, in Europe and the UK, the incidence of invasive meningococcal disease did slightly increase from 0.1 cases per 100,000 population in 2021 to an estimated 0.3 cases per 100,000 population in 2022. There were 1149 confirmed cases of bacterial meningitis reported in the 30 European Union/European Economic Area Member States, with serotype B being the major cause (62%), followed by serotype Y (16%).[22]European Centre for Disease Prevention and Control. Surveillance and updates for meningococcal disease. May 2024 [internet publication].
https://www.ecdc.europa.eu/en/meningococcal-disease/surveillance-and-disease-data
In the US, the incidence of meningococcal meningitis decreased from 0.72 in 100,000 in 1997 to an historic low of 0.1 cases per 100,000 in 2018.[11]Castelblanco RL, Lee M, Hasbun R. Epidemiology of bacterial meningitis in the USA from 1997 to 2010: a population-based observational study. Lancet Infect Dis. 2014 Sep;14(9):813-9.
http://www.ncbi.nlm.nih.gov/pubmed/25104307?tool=bestpractice.com
[23]Centers for Disease Control and Prevention. Morbidity and mortality weekly report (MMWR): meningococcal vaccination: recommendations of the advisory committee on immunization practices, United States, 2020. Sep 2020 [internet publication].
https://www.cdc.gov/mmwr/volumes/69/rr/rr6909a1.htm
However, there has been a recent sharp increase in US cases since 2021, specifically attributed to a strain of serogroup Y, ST-1466. The incidence of meningococcal disease now exceeds pre-pandemic levels. In 2023, 438 confirmed and probable cases were reported. This is the largest number of US meningococcal disease annual cases reported since 2014, with N meningitidis serogroup Y responsible for much of this recent increase.[24]Centers for Disease Control and Prevention. Meningococcal disease: meningococcal disease surveillance and trends. Apr 2025 [internet publication].
https://www.cdc.gov/meningococcal/php/surveillance/index.html
Per the Centers for Disease Control and Prevention, this strain was responsible for at least 68% of all serogroup Y cases reported in 2023. Cases of invasive meningococcal disease caused by this strain occurred in both males (65%) and females (35%) and disproportionately occurred in people ages 30-60 years (65%), Black or African American people (63%), and people with HIV (15%). In addition, most cases of invasive meningococcal disease caused by ST-1466 had varied clinical presentations; 64% presented with bacteremia, and at least 4% presented with septic arthritis. Of 94 patients with known outcomes, 17 (18%) died; this case-fatality rate is higher than the historic case-fatality rate of 11% reported for serogroup Y cases in 2017-2021.[25]Centers for Disease Control and Prevention. Emergency preparedness and response: increase in invasive serogroup Y meningococcal disease in the United States. Mar 2024 [internet publication].
https://www.cdc.gov/han/2024/han00505.html
[Figure caption and citation for the preceding image starts]: Laboratory-confirmed cases of invasive meningococcal disease in England by capsular group and epidemiologic year. The light blue and dark blue arrows denote the start of the national immunization programme against group C meningococcal (MenC) disease and group B meningococcal (MenB) disease, respectivelyPublic Health England [Citation ends].