View source for Medicine:Meningitis

{{Short description|Inflammation of the membranes around the brain and spinal cord}}
{{Infobox medical condition (new)
| name            = Meningitis
| image           = Meninges-en.svg
| caption         = Meninges of the [[Biology:Central nervous system|central nervous system]]: [[Medicine:Dura mater|dura mater]], arachnoid mater, and pia mater.
| field           = [[Medicine:Infectious disease (medical specialty)|Infectious disease]], [[Biology:Neurology|neurology]]
| symptoms        = [[Medicine:Fever|Fever]], [[Medicine:Headache|headache]], [[Medicine:Neck stiffness|neck stiffness]]<ref name=CDC2014B/>
| complications   = [[Medicine:Deafness|Deafness]], [[Medicine:Epilepsy|epilepsy]], [[Medicine:Hydrocephalus|hydrocephalus]], [[Medicine:Cognitive deficit|cognitive deficit]]s<ref name=Lancet/><ref name=NEJM/>
| onset           =
| duration        =
| causes          = Viral, bacterial, other<ref name=Ginsberg/>
| risks           =
| diagnosis       = [[Medicine:Lumbar puncture|Lumbar puncture]]<ref name=CDC2014B/>
| prevention      = [[Biology:Vaccination|Vaccination]]<ref name=Lancet/>
| treatment       =
| medication      = Antibiotics, antivirals, steroids<ref name=CDC2014B/><ref name=CDC2016Vir/><ref name=IDSA/>
| frequency       = 7.7 million (2019)<ref name="gdb2019">{{Cite web |title=Global Disease Burden 2019 |url=https://ghdx.healthdata.org/gbd-2019 |access-date=26 April 2022 |archive-date=19 April 2022 |archive-url=https://web.archive.org/web/20220419000912/https://ghdx.healthdata.org/gbd-2019 |url-status=live }}</ref>
| deaths          = 236,000 (2019)<ref name="gdb2019" />
}}
'''Meningitis''' is acute or [[Medicine:Chronic meningitis|chronic]] [[Medicine:Inflammation|inflammation]] of the protective membranes covering the [[Biology:Brain|brain]] and [[Biology:Spinal cord|spinal cord]], collectively called the [[Medicine:Meninges|meninges]].<ref>{{Cite journal |vauthors = Putz K, Hayani K, Zar FA |date = September 2013 |title=Meningitis |journal=Primary Care: Clinics in Office Practice |volume=40 |issue=3 |pages=707–726 |doi=10.1016/j.pop.2013.06.001 |pmid=23958365}}</ref> The most common symptoms are [[Medicine:Fever|fever]], [[Medicine:Headache|intense headache]], [[Medicine:Vomiting|vomiting]] and [[Medicine:Neck stiffness|neck stiffness]] and occasionally [[Medicine:Photophobia|photophobia]].<ref name=CDC2014B/>

Other symptoms include confusion or altered [[Philosophy:Consciousness|consciousness]], nausea, [[Medicine:Vomiting|vomiting]], and an [[Medicine:Photophobia|inability to tolerate light]] or [[Physics:Phonophobia|loud noises]].<ref name=CDC2014B/> Young children often exhibit only nonspecific symptoms, such as irritability, drowsiness, or poor feeding.<ref name="CDC2014B">{{Cite web |date=1 April 2014 |title=Bacterial Meningitis |url=https://www.cdc.gov/meningitis/bacterial.html |url-status=live |archive-url=https://web.archive.org/web/20160305021530/http://www.cdc.gov/meningitis/bacterial.html |archive-date=5 March 2016 |access-date=5 March 2016 |publisher=U.S. Centers for Disease Control and Prevention (CDC) }}</ref> A non-blanching rash (a rash that does not fade when a glass is rolled over it) may also be present.<ref>{{Cite web |date=20 October 2017 |title=NHS medical conditions meningitis |url=https://www.nhs.uk/conditions/meningitis/ |access-date=26 April 2022 |publisher=National Health Service (NHS) |archive-date=26 April 2022 |archive-url=https://web.archive.org/web/20220426133024/https://www.nhs.uk/conditions/meningitis/ |url-status=live }}</ref>

The inflammation may be caused by infection with [[Biology:Virus|virus]]es, [[Medicine:Pathogenic bacteria|bacteria]], [[Biology:Pathogenic fungus|fungi]] or parasites.<ref name=WHO2023/> Non-infectious causes include [[Medicine:Malignancy|malignancy]] ([[Medicine:Cancer|cancer]]), [[Medicine:Subarachnoid hemorrhage|subarachnoid hemorrhage]], chronic inflammatory disease ([[Medicine:Sarcoidosis|sarcoidosis]]) and certain [[Chemistry:Medication|drugs]].<ref name="Ginsberg">{{Cite journal |vauthors=Ginsberg L |date=March 2004 |title=Difficult and recurrent meningitis |journal=Journal of Neurology, Neurosurgery, and Psychiatry |volume=75 Suppl 1 |issue=90001 |pages=i16–21 |doi=10.1136/jnnp.2003.034272 |pmc=1765649 |pmid=14978146 }}</ref> Meningitis can be life-threatening because of the inflammation's proximity to the brain and spinal cord; therefore, the condition is classified as a [[Medicine:Medical emergency|medical emergency]].<ref name=Lancet/><ref name="IDSA">{{Cite journal |vauthors=Tunkel AR, Hartman BJ, Kaplan SL, Kaufman BA, Roos KL, Scheld WM, Whitley RJ |date=November 2004 |title=Practice guidelines for the management of bacterial meningitis |journal=Clinical Infectious Diseases |volume=39 |issue=9 |pages=1267–84 |doi=10.1086/425368 |pmid=15494903 | doi-access=free | title-link=doi }}</ref> A [[Medicine:Lumbar puncture|lumbar puncture]], in which a needle is inserted into the spinal canal to collect a sample of [[Biology:Cerebrospinal fluid|cerebrospinal fluid]] (CSF), can diagnose or exclude meningitis.<ref name=CDC2014B/><ref name=IDSA/>

Some forms of meningitis are preventable by [[Biology:Immunization|immunization]] with the [[Medicine:Meningococcal vaccine|meningococcal]], [[Medicine:Mumps vaccine|mumps]], [[Medicine:Pneumococcal vaccine|pneumococcal]], and [[Medicine:Hib vaccine|Hib vaccine]]s.<ref name="Lancet">{{Cite journal |vauthors=Sáez-Llorens X, McCracken GH |date=June 2003 |title=Bacterial meningitis in children |journal=Lancet |volume=361 |issue=9375 |pages=2139–48 |doi=10.1016/S0140-6736(03)13693-8 |pmid=12826449 |s2cid=6226323}}</ref> Giving [[Chemistry:Antibiotic|antibiotic]]s to people with significant exposure to certain types of meningitis may also be useful.<ref name=CDC2014B/> The first treatment in acute meningitis consists of promptly giving antibiotics and sometimes [[Biology:Antiviral drug|antiviral drug]]s.<ref name=CDC2014B/><ref name="CDC2016Vir">{{Cite web |date=26 November 2014 |title=Viral Meningitis |url=https://www.cdc.gov/meningitis/viral.html |url-status=live |archive-url=https://web.archive.org/web/20160304203230/http://www.cdc.gov/meningitis/viral.html |archive-date=4 March 2016 |access-date=5 March 2016 |publisher=U.S. Centers for Disease Control and Prevention (CDC) }}</ref> [[Biology:Corticosteroid|Corticosteroid]]s can also be used to prevent complications from excessive inflammation.<ref name=NEJM/><ref name=IDSA/> Meningitis can lead to serious long-term consequences such as [[Medicine:Deafness|deafness]], [[Medicine:Epilepsy|epilepsy]], [[Medicine:Hydrocephalus|hydrocephalus]], or [[Medicine:Cognitive deficit|cognitive deficit]]s, especially if not treated quickly.<ref name=Lancet/><ref name="NEJM">{{Cite journal |vauthors=van de Beek D, de Gans J, Tunkel AR, Wijdicks EF |date=January 2006 |title=Community-acquired bacterial meningitis in adults |journal=The New England Journal of Medicine |volume=354 |issue=1 |pages=44–53 |doi=10.1056/NEJMra052116 |pmid=16394301}}</ref>

In 2019, meningitis was diagnosed in about 7.7 million people worldwide,<ref name="gdb2019" /> of whom 236,000 died, down from 433,000 deaths in 1990.<ref name="gdb2019" /> With appropriate treatment, the risk of death in bacterial meningitis is less than 15%.<ref name=CDC2014B/> Outbreaks of bacterial meningitis occur between December and June each year in an area of [[Place:Sub-Saharan Africa|sub-Saharan Africa]] known as the meningitis belt.<ref name=WHO2015/> Smaller outbreaks may also occur in other areas of the world.<ref name="WHO2015">{{Cite web |date=November 2015 |title=Meningococcal meningitis Fact sheet N°141 |url=https://www.who.int/mediacentre/factsheets/fs141/en/ |url-status=live |archive-url=https://web.archive.org/web/20160305103408/http://www.who.int/mediacentre/factsheets/fs141/en/ |archive-date=5 March 2016 |access-date=5 March 2016 |publisher=[[Organization:World Health Organization|World Health Organization]] (WHO) }}</ref> The word meningitis comes from the [[Social:Ancient Greek|Greek]] μῆνιγξ ''meninx'', "membrane", and the medical suffix ''-itis'', "inflammation".<ref>{{Cite book |url=https://books.google.com/books?id=_QGaoiFCIDMC&pg=PT4755 |title=Mosby's pocket dictionary of medicine, nursing & health professions |date=2010 |publisher=Mosby/Elsevier |isbn=978-0-323-06604-4 |edition=6th |location=St. Louis |page=traumatic meningitis |archive-url=https://web.archive.org/web/20170910145715/https://books.google.com/books?id=_QGaoiFCIDMC&pg=PT4755 |archive-date=10 September 2017 |url-status=live}}</ref><ref>{{Cite book |title=A Greek-English Lexicon |vauthors=Liddell HG, Scott R |publisher=Clarendon Press |year=1940 |location=Oxford |chapter=μῆνιγξ |chapter-url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dmh%3Dnigc |archive-url=https://web.archive.org/web/20131108025517/http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dmh%3Dnigc |archive-date=8 November 2013 |url-status=live }}</ref>

==Signs and symptoms==

===Clinical features===
[[File:Neck stiffness.jpg|thumb|right|Neck stiffness, Texas meningitis epidemic of 1911–12]]
In adults, the most common symptom of meningitis is a severe [[Medicine:Headache|headache]], occurring in almost 90% of cases of bacterial meningitis, followed by neck stiffness (the inability to flex the neck forward passively due to increased neck [[Biology:Muscle tone|muscle tone]] and stiffness).<ref name="vdBeek2004">{{Cite journal |vauthors=van de Beek D, de Gans J, Spanjaard L, Weisfelt M, Reitsma JB, Vermeulen M |date=October 2004 |title=Clinical features and prognostic factors in adults with bacterial meningitis |url=https://pure.uva.nl/ws/files/4089960/45119_204449y.pdf |url-status=live |journal=The New England Journal of Medicine |volume=351 |issue=18 |pages=1849–59 |doi=10.1056/NEJMoa040845 |pmid=15509818 |archive-url=https://web.archive.org/web/20200803222631/https://pure.uva.nl/ws/files/4089960/45119_204449y.pdf |archive-date=3 August 2020 |access-date=30 December 2018 |s2cid=22287169}}</ref> The classic triad of diagnostic signs consists of neck stiffness, sudden [[Medicine:Fever#Types|high fever]], and [[Medicine:Altered level of consciousness|altered mental status]]; however, all three features are present in only 44–46% of bacterial meningitis cases.<ref name=vdBeek2004/><ref name="Attia">{{Cite journal |vauthors=Attia J, Hatala R, Cook DJ, Wong JG |date=July 1999 |title=The rational clinical examination. Does this adult patient have acute meningitis? |journal=JAMA |volume=282 |issue=2 |pages=175–81 |doi=10.1001/jama.282.2.175 |pmid=10411200}}</ref> If none of the three signs are present, acute meningitis is extremely unlikely.<ref name=Attia/> Other signs commonly associated with meningitis include [[Medicine:Photophobia|photophobia]] (intolerance to bright light) and [[Physics:Phonophobia|phonophobia]] (intolerance to loud noises). Small children often do not exhibit the aforementioned symptoms, and may only be irritable and look unwell.<ref name=Lancet/> The [[Medicine:Fontanelle|fontanelle]] (the soft spot on the top of a baby's head) can bulge in infants aged up to 6&nbsp;months. Other features that distinguish meningitis from less severe illnesses in young children are leg pain, cold extremities, and an abnormal skin color.<ref name="SIGN">{{Cite journal |vauthors=Theilen U, Wilson L, Wilson G, Beattie JO, Qureshi S, Simpson D |date=June 2008 |title=Management of invasive meningococcal disease in children and young people: summary of SIGN guidelines |journal=BMJ |volume=336 |issue=7657 |pages=1367–70 |doi=10.1136/bmj.a129 |pmc=2427067 |pmid=18556318}}</ref><ref>{{Cite book |url=http://www.sign.ac.uk/pdf/sign102.pdf |title=Management of invasive meningococcal disease in children and young people |date=May 2008 |publisher=Scottish Intercollegiate Guidelines Network (SIGN) |isbn=978-1-905813-31-5 |location=Edinburgh |archive-url=https://web.archive.org/web/20140709111421/http://www.sign.ac.uk/pdf/sign102.pdf |archive-date=9 July 2014 |url-status=live }}</ref>

Neck stiffness occurs in 70% of bacterial meningitis in adults.<ref name=Attia/> Other signs include the presence of positive [[Medicine:Kernig's sign|Kernig's sign]] or Brudziński sign. Kernig's sign is assessed with the person lying [[Biology:Supine position|supine]], with the hip and knee flexed to 90&nbsp;degrees. In a person with a positive Kernig's sign, pain limits passive extension of the knee. A positive Brudzinski's sign occurs when flexion of the neck causes involuntary flexion of the knee and hip. Although Kernig's sign and Brudzinski's sign are both commonly used to screen for meningitis, the [[Sensitivity and specificity|sensitivity]] of these tests is limited.<ref name=Attia/><ref name="Thomas_2002">{{Cite journal |vauthors=Thomas KE, Hasbun R, Jekel J, Quagliarello VJ |date=July 2002 |title=The diagnostic accuracy of Kernig's sign, Brudzinski's sign, and nuchal rigidity in adults with suspected meningitis |journal=Clinical Infectious Diseases |volume=35 |issue=1 |pages=46–52 |doi=10.1086/340979 |pmid=12060874 |s2cid=3196834 | doi-access=free | title-link=doi }}</ref> They do, however, have very good [[Sensitivity and specificity|specificity]] for meningitis: the signs rarely occur in other diseases.<ref name=Attia/> Another test, known as the "jolt accentuation maneuver" helps determine whether meningitis is present in those reporting fever and headache. A person is asked to rapidly rotate the head horizontally; if this does not make the headache worse, meningitis is unlikely.<ref name=Attia/>

Other problems can produce symptoms similar to those above, but from non-meningitic causes. This is called meningism or pseudomeningitis.<ref>{{Cite web |title=Meningitis |url=https://www.who.int/health-topics/meningitis |access-date=25 April 2022 |publisher=[[Organization:World Health Organization|World Health Organization]] (WHO) |archive-date=25 April 2022 |archive-url=https://web.archive.org/web/20220425134428/https://www.who.int/health-topics/meningitis |url-status=live }}</ref>

Meningitis caused by the bacterium ''[[Biology:Neisseria meningitidis|Neisseria meningitidis]]'' (known as "meningococcal meningitis") can be differentiated from meningitis with other causes by a rapidly spreading petechial rash, which may precede other symptoms.<ref name=SIGN/> The rash consists of numerous small, irregular purple or red spots ("petechiae") on the trunk, lower extremities, mucous membranes, conjunctiva, and (occasionally) the palms of the hands or soles of the feet. The rash is typically non-blanching; the redness does not disappear when pressed with a finger or a glass tumbler. Although this rash is not necessarily present in meningococcal meningitis, it is relatively specific for the disease; it does, however, occasionally occur in meningitis due to other bacteria.<ref name=Lancet/> Other clues on the cause of meningitis may be the skin signs of hand, foot and mouth disease and [[Medicine:Genital herpes|genital herpes]], both of which are associated with various forms of viral meningitis.<ref name="LoganMacMahon">{{Cite journal |vauthors=Logan SA, MacMahon E |date=January 2008 |title=Viral meningitis |journal=BMJ |volume=336 |issue=7634 |pages=36–40 |doi=10.1136/bmj.39409.673657.AE |pmc=2174764 |pmid=18174598}}</ref>

===Early complications===
[[File:Charlotte Cleverley-Bisman Meningicoccal Disease.jpg|thumb|Charlotte Cleverley-Bisman developed severe meningococcal meningitis as a young child; in her case, the petechial rash progressed to gangrene and required amputation of all limbs. She survived the disease and became a poster child for a meningitis vaccination campaign in New Zealand.]]
Additional problems may occur in the early stage of the illness. These may require specific treatment, and sometimes indicate severe illness or worse prognosis. The infection may trigger [[Medicine:Sepsis|sepsis]], a [[Medicine:Systemic inflammatory response syndrome|systemic inflammatory response syndrome]] of falling [[Physics:Blood pressure|blood pressure]], [[Medicine:Tachycardia|fast heart rate]], high or abnormally low temperature, and rapid breathing. Very low blood pressure may occur at an early stage, especially but not exclusively in meningococcal meningitis; this may lead to insufficient blood supply to other organs.<ref name=Lancet/> [[Medicine:Disseminated intravascular coagulation|Disseminated intravascular coagulation]], the excessive activation of blood clotting, may obstruct blood flow to organs and paradoxically increase the bleeding risk. [[Medicine:Gangrene|Gangrene]] of limbs can occur in [[Medicine:Meningococcal disease|meningococcal disease]].<ref name=Lancet/> Severe meningococcal and pneumococcal infections may result in hemorrhaging of the adrenal glands, leading to Waterhouse-Friderichsen syndrome, which is often fatal.<ref name="pmid9696186">{{Cite journal |vauthors=Varon J, Chen K, Sternbach GL |year=1998 |title=Rupert Waterhouse and Carl Friderichsen: adrenal apoplexy |journal=The Journal of Emergency Medicine |volume=16 |issue=4 |pages=643–47 |doi=10.1016/S0736-4679(98)00061-4 |pmid=9696186}}</ref>

The [[Medicine:Cerebral edema|brain tissue may swell]], [[Medicine:Intracranial pressure|pressure inside the skull]] may increase and the swollen brain may [[Medicine:Brain herniation|herniate]] through the skull base. This may be noticed by a decreasing level of consciousness, loss of the [[Biology:Pupillary light reflex|pupillary light reflex]], and abnormal posturing.<ref name=NEJM/> The inflammation of the brain tissue may also obstruct the normal flow of CSF around the brain ([[Medicine:Hydrocephalus|hydrocephalus]]).<ref name=NEJM/> [[Medicine:Seizure|Seizure]]s may occur for various reasons; in children, seizures are common in the early stages of meningitis (in 30% of cases) and do not necessarily indicate an underlying cause.<ref name=IDSA/> Seizures may result from increased pressure and from areas of inflammation in the brain tissue.<ref name=NEJM/> Focal seizures (seizures that involve one limb or part of the body), persistent seizures, late-onset seizures and those that are difficult to control with medication indicate a poorer long-term outcome.<ref name=Lancet/>

Inflammation of the meninges may lead to abnormalities of the cranial nerves, a group of nerves arising from the brain stem that supply the head and neck area and which control, among other functions, eye movement, facial muscles, and hearing.<ref name=Lancet/><ref name=Attia/> Visual symptoms and [[Medicine:Hearing loss|hearing loss]] may persist after an episode of meningitis.<ref name=Lancet/> Inflammation of the brain ([[Medicine:Encephalitis|encephalitis]]) or its [[Biology:Blood vessel|blood vessel]]s ([[Medicine:Cerebral vasculitis|cerebral vasculitis]]), as well as the formation of [[Medicine:Thrombosis|blood clots]] in the veins ([[Medicine:Cerebral venous sinus thrombosis|cerebral venous thrombosis]]), may all lead to weakness, loss of sensation, or abnormal movement or function of the part of the body supplied by the affected area of the brain.<ref name=Lancet/><ref name=NEJM/>

==Causes==
Meningitis is typically caused by an [[Medicine:Infection|infection]]. Most infections are due to [[Biology:Virus|virus]]es, and others due to [[Medicine:Pathogenic bacteria|bacteria]], [[Biology:Pathogenic fungus|fungi]], and [[Earth:Parasitism|parasites]].<ref name=WHO2023/> Mostly the parasites are [[Biology:Parasitic worm|parasitic worm]]s,<ref name=Ginsberg/> but can also rarely include [[Earth:Parasitism|parasitic]] [[Biology:Amoeba (genus)|amoebae]].<ref name="CDC2022">{{cite web |title=Amebic Meningitis |url=https://www.cdc.gov/meningitis/amebic.html |publisher=U.S. Centers for Disease Control and Prevention (CDC) |date=12 August 2022 |access-date=31 May 2023 |archive-date=24 May 2023 |archive-url=https://web.archive.org/web/20230524200711/https://www.cdc.gov/meningitis/amebic.html |url-status=live }}</ref> Meningitis may also result from various non-infectious causes.<ref name= Ginsberg/> The term ''aseptic meningitis'' refers to cases of meningitis in which no bacterial infection can be demonstrated. This type of meningitis is usually caused by viruses, but it may be due to bacterial infection that has already been partially treated, when bacteria disappear from the meninges, or when pathogens infect a space adjacent to the meninges (such as [[Medicine:Sinusitis|sinusitis]]). [[Medicine:Endocarditis|Endocarditis]] (an infection of the heart valves which spreads small clusters of bacteria through the bloodstream) may cause aseptic meningitis. Aseptic meningitis may also result from infection with spirochetes, a group of bacteria that includes ''[[Biology:Treponema pallidum|Treponema pallidum]]'' (the cause of [[Medicine:Syphilis|syphilis]]) and ''[[Biology:Borrelia burgdorferi|Borrelia burgdorferi]]'' (known for causing [[Unsolved:Lyme disease|Lyme disease]]), and may also result from cerebral malaria (malaria infecting the brain).<ref name= Ginsberg/>

===Bacterial===
[[File:Streptococcus pneumoniae - A causative bacteria of meningitis.jpg|thumb|''Streptococcus pneumoniae''—a causative bacterium of meningitis (illustration)]]

The types of bacteria that cause bacterial meningitis vary according to the infected individual's age group.
* In premature babies and newborns up to three months old, common causes are ''group B streptococci'' (subtypes III which normally inhabit the [[Biology:Vagina|vagina]] and are mainly a cause during the first week of life) and bacteria that normally inhabit the [[Biology:Gastrointestinal tract|digestive tract]] such as ''[[Biology:Escherichia coli|Escherichia coli]]'' (carrying the K1 antigen). ''[[Biology:Listeria monocytogenes|Listeria monocytogenes]]'' (serotype IVb) can be contracted when consuming improperly prepared food such as dairy products, produce and deli meats,<ref>{{Cite web |date=6 August 2019 |title=Bacterial Meningitis |url= https://www.cdc.gov/meningitis/bacterial.html |publisher=U.S. Centers for Disease Control and Prevention (CDC) |url-status=live |archive-url= https://web.archive.org/web/20160305021530/http://www.cdc.gov/meningitis/bacterial.html |archive-date=5 March 2016 |access-date=3 December 2020 }}</ref><ref>{{Cite web |date= 17 June 2019 |title=Prevent Listeria |url= https://www.cdc.gov/listeria/prevention.html |url-status=live |archive-url= https://web.archive.org/web/20200507083402/https://www.cdc.gov/listeria/prevention.html |archive-date=7 May 2020 |access-date=3 December 2020 |publisher=U.S. Centers for Disease Control and Prevention (CDC) }}</ref> and may cause meningitis in the newborn.<ref>{{Cite web |date=22 October 2015 |title=Listeria (Listeriosis) |url= https://www.cdc.gov/listeria/index.html |url-status=live |archive-url=https://web.archive.org/web/20151219020207/http://www.cdc.gov/listeria/index.html |archive-date=19 December 2015 |access-date=23 December 2015 |publisher=U.S. Centers for Disease Control and Prevention (CDC) | df=dmy-all}}</ref>
* Older children are more commonly affected by ''[[Biology:Neisseria meningitidis|Neisseria meningitidis]]'' (meningococcus) and ''[[Biology:Streptococcus pneumoniae|Streptococcus pneumoniae]]'' (serotypes 6, 9, 14, 18 and 23) and those under five by [[Biology:Haemophilus influenzae|''Haemophilus influenzae'' type B]] (in countries that do not offer vaccination).<ref name=Lancet/><ref name=IDSA/>
* In adults, ''Neisseria meningitidis'' and ''Streptococcus pneumoniae'' together cause 80% of bacterial meningitis cases. Risk of infection with ''Listeria monocytogenes'' is increased in people over 50 years old.<ref name=NEJM/><ref name=IDSA/> The introduction of pneumococcal vaccine has lowered rates of pneumococcal meningitis in both children and adults.<ref name="Hsu">{{Cite journal |vauthors=Hsu HE, Shutt KA, Moore MR, Beall BW, Bennett NM, Craig AS, Farley MM, Jorgensen JH, Lexau CA, Petit S, Reingold A, Schaffner W, Thomas A, Whitney CG, Harrison LH |date=January 2009 |title=Effect of pneumococcal conjugate vaccine on pneumococcal meningitis |journal=The New England Journal of Medicine |volume=360 |issue=3 |pages=244–56 |doi=10.1056/NEJMoa0800836 |pmc= 4663990 |pmid=19144940}}</ref>

A [[Medicine:Head injury|head injury]] potentially allows nasal cavity bacteria to enter the meningeal space. Similarly, devices in the brain and meninges, such as [[Medicine:Cerebral shunt|cerebral shunt]]s, extraventricular drains or [[Medicine:Ommaya reservoir|Ommaya reservoir]]s, carry an increased risk of meningitis. In these cases, people are more likely to be infected with ''Staphylococci'', ''[[Biology:Pseudomonas|Pseudomonas]]'', and other [[Biology:Gram-negative bacteria|Gram-negative bacteria]].<ref name=IDSA/> These pathogens are also associated with meningitis in people with an impaired immune system.<ref name=Lancet/> An infection in the head and neck area, such as [[Medicine:Otitis media|otitis media]] or [[Medicine:Mastoiditis|mastoiditis]], can lead to meningitis in a small proportion of people.<ref name=IDSA/> Recipients of [[Cochlear implant|cochlear implant]]s for hearing loss are more at risk for pneumococcal meningitis.<ref>{{Cite journal |vauthors= Wei BP, Robins-Browne RM, Shepherd RK, Clark GM, O'Leary SJ |date=January 2008 |title=Can we prevent cochlear implant recipients from developing pneumococcal meningitis? |journal=Clinical Infectious Diseases |volume=46 |issue=1 |pages= e1–7 |doi=10.1086/524083 |pmid= 18171202 | doi-access=free | title-link=doi }}</ref> In rare cases, ''Enterococcus'' spp. can be responsible for meningitis, both community and hospital-acquired, usually as a secondary result of trauma or surgery, or due to intestinal diseases (e.g., strongyloidiasis).<ref>{{cite journal |last1=Zeana |first1=C |last2=Kubin |first2=CJ |last3=Della Latta |first3=P |last4=Hammer |first4=SM |title=Vancomycin-resistant Enterococcus faecium meningitis successfully managed with linezolid: case report and review of the literature |journal=Clin Infect Dis |date=2001 |volume=33 |issue=4 |pages=477–482 |doi=10.1086/321896 |pmid=11462183|doi-access=free }}</ref>

Tuberculous meningitis, which is meningitis caused by ''[[Biology:Mycobacterium tuberculosis|Mycobacterium tuberculosis]]'', is more common in people from countries in which [[Medicine:Tuberculosis|tuberculosis]] is endemic, but is also encountered in people with immune problems, such as AIDS.<ref name="Tuberc">{{Cite journal |vauthors=Thwaites G, Chau TT, Mai NT, Drobniewski F, McAdam K, Farrar J |date=March 2000 |title=Tuberculous meningitis |journal=Journal of Neurology, Neurosurgery, and Psychiatry |volume=68 |issue=3 |pages=289–99 |doi= 10.1136/jnnp.68.3.289 |pmc=1736815 |pmid=10675209 }}</ref>

Recurrent bacterial meningitis may be caused by persisting anatomical defects, either congenital or acquired, or by disorders of the [[Biology:Immune system|immune system]].<ref name= "Tebruegge">{{Cite journal |vauthors= Tebruegge M, Curtis N |date=July 2008 |title=Epidemiology, etiology, pathogenesis, and diagnosis of recurrent bacterial meningitis |journal= Clinical Microbiology Reviews |volume=21 |issue=3 |pages=519–37 |doi=10.1128/CMR.00009-08 |pmc= 2493086 |pmid=18625686}}</ref> Anatomical defects allow continuity between the external environment and the [[Biology:Nervous system|nervous system]]. The most common cause of recurrent meningitis is a [[Medicine:Skull fracture|skull fracture]],<ref name= Tebruegge/> particularly fractures that affect the base of the skull or extend towards the [[Medicine:Paranasal sinuses|sinuses]] and petrous pyramids.<ref name=Tebruegge/> Approximately 59% of recurrent meningitis cases are due to such anatomical abnormalities, 36% are due to immune deficiencies (such as [[Medicine:Complement deficiency|complement deficiency]], which predisposes especially to recurrent meningococcal meningitis), and 5% are due to ongoing infections in areas adjacent to the meninges.<ref name= Tebruegge/>

===Viral===
Viruses that cause meningitis include [[Biology:Enterovirus|enterovirus]]es, herpes simplex virus (generally type 2, which produces most genital sores; less commonly type 1), varicella zoster virus (known for causing [[Medicine:Chickenpox|chickenpox]] and shingles), [[Medicine:Mumps|mumps virus]], [[Biology:HIV|HIV]], [[Medicine:Lymphocytic choriomeningitis|LCMV]],<ref name="LoganMacMahon" /> Arboviruses (acquired from a mosquito or other insect), and the influenza virus.<ref>{{Cite web |date=19 February 2019 |title=Meningitis {{!}} Viral| url= https://www.cdc.gov/meningitis/viral.html |url-status=live |archive-url= https://web.archive.org/web/20160304203230/http://www.cdc.gov/meningitis/viral.html |archive-date=4 March 2016 |access-date=26 March 2019 |publisher=U.S. Centers for Disease Control and Prevention (CDC) }}</ref> [[Medicine:Mollaret's meningitis|Mollaret's meningitis]] is a chronic recurrent form of herpes meningitis; it is thought to be caused by herpes simplex virus type 2.<ref>{{Cite journal |vauthors= Shalabi M, Whitley RJ |date=November 2006 |title=Recurrent benign lymphocytic meningitis |journal=Clinical Infectious Diseases |volume=43 |issue= 9 |pages=1194–97 |doi= 10.1086/508281 |pmid=17029141 | doi-access=free | title-link=doi }}</ref>

===Fungal===
There are a number of risk factors for [[Medicine:Fungal meningitis|fungal meningitis]], including the use of [[Chemistry:Immunosuppressant|immunosuppressant]]s (such as after [[Medicine:Organ transplantation|organ transplantation]]), HIV/AIDS,<ref>{{Cite journal |vauthors=Raman Sharma R |year=2010 |title=Fungal infections of the nervous system: current perspective and controversies in management |journal=International Journal of Surgery |volume=8 |issue=8 |pages= 591–601 |doi=10.1016/j.ijsu.2010.07.293 |pmid=20673817 | doi-access=free | title-link=doi }}</ref> and the loss of immunity associated with aging.<ref name="Sirven2008">{{Cite book |url=https://books.google.com/books?id=c1tL8C9ryMQC&pg=PA439 |title=Clinical neurology of the older adult |vauthors=Sirven JI, Malamut BL |publisher=Wolters Kluwer Health/Lippincott Williams & Wilkins |year=2008 |isbn=978-0-7817-6947-1 |edition=2nd |location=Philadelphia |page=439 |archive-url=https://web.archive.org/web/20160515054405/https://books.google.com/books?id=c1tL8C9ryMQC&pg=PA439 |archive-date=15 May 2016 |url-status=live}}</ref> It is uncommon in those with a normal immune system<ref>{{Cite journal |vauthors=Honda H, Warren DK |date=September 2009 |title=Central nervous system infections: meningitis and brain abscess |journal=Infectious Disease Clinics of North America |volume=23 |issue=3 |pages=609–23 |doi=10.1016/j.idc.2009.04.009 |pmid=19665086}}</ref> but has occurred with [[Medicine:New England Compounding Center meningitis outbreak|medication contamination]].<ref name="NECC">{{Cite journal |vauthors=Kauffman CA, Pappas PG, Patterson TF |date=June 2013 |title=Fungal infections associated with contaminated methylprednisolone injections |journal=The New England Journal of Medicine |volume=368 |issue=26 |pages=2495–500 |doi=10.1056/NEJMra1212617 |pmid=23083312|doi-access=free }}</ref> Symptom onset is typically more gradual, with headaches and fever being present for at least a couple of weeks before diagnosis.<ref name=Sirven2008/> The most common fungal meningitis is cryptococcal meningitis due to ''[[Biology:Cryptococcus neoformans|Cryptococcus neoformans]]''.<ref>{{Cite book |url=https://books.google.com/books?id=8IySvRT52KkC&pg=PA77 |title=Essentials of clinical mycology |vauthors=Kauffman CA, Pappas PG, Sobel JD, Dismukes WE |date=1 January 2011 |publisher=Springer |isbn=978-1-4419-6639-1 |edition=2nd |location=New York |page=77 |archive-url=https://web.archive.org/web/20160510051334/https://books.google.com/books?id=8IySvRT52KkC&pg=PA77 |archive-date=10 May 2016 |url-status=live}}</ref> In Africa, cryptococcal meningitis is now the most common cause of meningitis in multiple studies,<ref>{{Cite journal |vauthors=Durski KN, Kuntz KM, Yasukawa K, Virnig BA, Meya DB, Boulware DR |date=July 2013 |title=Cost-effective diagnostic checklists for meningitis in resource-limited settings |journal=Journal of Acquired Immune Deficiency Syndromes |volume=63 |issue=3 |pages=e101–08 |doi=10.1097/QAI.0b013e31828e1e56 |pmc=3683123 |pmid=23466647}}</ref><ref>{{Cite book |url=https://books.google.com/books?id=8IySvRT52KkC&pg=PA31 |title=Essentials of clinical mycology |vauthors=Kauffman CA, Pappas PG, Sobel JD, Dismukes WE |date=1 January 2011 |publisher=Springer |isbn=978-1-4419-6639-1 |edition=2nd |location=New York |page=31 |archive-url=https://web.archive.org/web/20160516212901/https://books.google.com/books?id=8IySvRT52KkC&pg=PA31 |archive-date=16 May 2016 |url-status= live}}</ref> and it accounts for 20–25% of AIDS-related deaths in Africa.<ref name="ReferenceA">{{Cite journal |vauthors=Park BJ, Wannemuehler KA, Marston BJ, Govender N, Pappas PG, Chiller TM |date=February 2009 |title=Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDS |journal=AIDS |volume=23 |issue=4 |pages=525–30 |doi= 10.1097/QAD.0b013e328322ffac |pmid=19182676 |s2cid=5735550| doi-access=free | title-link=doi }}</ref> Other less common pathogenic fungi which can cause meningitis include: ''[[Biology:Coccidioides immitis|Coccidioides immitis]]'', ''[[Biology:Histoplasma capsulatum|Histoplasma capsulatum]]'', ''[[Biology:Blastomyces dermatitidis|Blastomyces dermatitidis]]'', and ''[[Biology:Candida (fungus)|Candida]]'' species.<ref name=Sirven2008/>

===Parasitic===
A [[Biology:Parasitic worm|parasitic worm]] is often assumed to be the cause of '''eosinophilic meningitis''' when there is a predominance of eosinophils (a type of white blood cell) found in the cerebrospinal fluid. The most common [[Biology:Parasite|parasite]]s implicated are ''[[Biology:Angiostrongylus cantonensis|Angiostrongylus cantonensis]]'', ''[[Biology:Gnathostoma spinigerum|Gnathostoma spinigerum]]'', ''[[Biology:Schistosoma|Schistosoma]]'', as well as the conditions [[Medicine:Cysticercosis|cysticercosis]], [[Medicine:Toxocariasis|toxocariasis]], [[Biology:Baylisascaris procyonis|baylisascariasis]], [[Medicine:Paragonimiasis|paragonimiasis]], and a number of rarer infections and noninfective conditions.<ref name="Graeff">{{Cite journal |vauthors=Graeff-Teixeira C, da Silva AC, Yoshimura K |date=April 2009 |title=Update on eosinophilic meningoencephalitis and its clinical relevance |journal=Clinical Microbiology Reviews |volume=22 |issue=2 |pages= 322–348, Table of Contents |doi= 10.1128/CMR.00044-08 |pmc= 2668237 |pmid=19366917 }}</ref>

Rarely, free-living parasitic [[Biology:Amoeba (genus)|amoebae]] can cause [[Medicine:Naegleriasis|naegleriasis]], also called ''amebic meningitis'',<ref name="CDC2022"/> a type of meningoencephalitis where not only the meninges are affected but also the brain tissue.

===Non-infectious===
Meningitis may occur as the result of several non-infectious causes: spread of [[Medicine:Cancer|cancer]] to the meninges (''malignant or neoplastic meningitis'')<ref name= "Chamberlain">{{Cite journal |vauthors= Gleissner B, Chamberlain MC |date=May 2006 |title=Neoplastic meningitis |journal=The Lancet. Neurology |volume=5 |issue=5 |pages= 443–52 |doi=10.1016/S1474-4422(06)70443-4 |pmid=16632315 |s2cid=21335554}}</ref> and certain drugs (mainly non-steroidal anti-inflammatory drugs, [[Chemistry:Antibiotic|antibiotic]]s and intravenous immunoglobulins).<ref name="ArchInternMed">{{Cite journal |vauthors=Moris G, Garcia-Monco JC |date=June 1999 |title=The challenge of drug-induced aseptic meningitis |journal=Archives of Internal Medicine |volume=159 |issue=11 |pages=1185–94 |doi=10.1001/archinte.159.11.1185 |pmid=10371226 | doi-access=free | title-link=doi }}</ref> It may also be caused by several inflammatory conditions, such as [[Medicine:Sarcoidosis|sarcoidosis]] (which is then called [[Medicine:Neurosarcoidosis|neurosarcoidosis]]), connective tissue disorders such as [[Medicine:Systemic lupus erythematosus|systemic lupus erythematosus]], and certain forms of [[Medicine:Vasculitis|vasculitis]] (inflammatory conditions of the blood vessel wall), such as [[Medicine:Behçet's disease|Behçet's disease]].<ref name= Ginsberg/> Epidermoid cysts and [[Medicine:Dermoid cyst|dermoid cyst]]s may cause meningitis by releasing irritant matter into the subarachnoid space.<ref name= Ginsberg/><ref name=Tebruegge/> Rarely, migraine may cause meningitis, but this diagnosis is usually only made when other causes have been eliminated.<ref name=Ginsberg/>

==Mechanism==
The meninges comprise three membranes that, together with the [[Biology:Cerebrospinal fluid|cerebrospinal fluid]], enclose and protect the [[Biology:Brain|brain]] and [[Biology:Spinal cord|spinal cord]] (the [[Biology:Central nervous system|central nervous system]]). The pia mater is a delicate impermeable membrane that firmly adheres to the surface of the brain, following all the minor contours. The arachnoid mater (so named because of its spider-web-like appearance) is a loosely fitting sac on top of the pia mater. The subarachnoid space separates the arachnoid and pia mater membranes and is filled with cerebrospinal fluid. The outermost membrane, the [[Medicine:Dura mater|dura mater]], is a thick durable membrane, which is attached to both the arachnoid membrane and the skull.

In bacterial meningitis, bacteria reach the meninges by one of two main routes: through the bloodstream (hematogenous spread) or through direct contact between the meninges and either the nasal cavity or the skin. In most cases, meningitis follows invasion of the bloodstream by organisms that live on [[Biology:Mucous membrane|mucosal surfaces]] such as the nasal cavity. This is often in turn preceded by viral infections, which break down the normal barrier provided by the mucosal surfaces. Once bacteria have entered the bloodstream, they enter the subarachnoid space in places where the [[Biology:Blood–brain barrier|blood–brain barrier]] is vulnerable&nbsp;– such as the choroid plexus. Meningitis occurs in 25% of newborns with bloodstream infections due to group B streptococci; this phenomenon is much less common in adults.<ref name=Lancet/> Direct contamination of the cerebrospinal fluid may arise from indwelling devices, skull fractures, or infections of the nasopharynx or the nasal sinuses that have formed a tract with the subarachnoid space (see above); occasionally, congenital defects of the [[Medicine:Dura mater|dura mater]] can be identified.<ref name=Lancet/>

The large-scale [[Medicine:Inflammation|inflammation]] that occurs in the subarachnoid space during meningitis is not a direct result of bacterial infection but can rather largely be attributed to the response of the [[Biology:Immune system|immune system]] to the entry of bacteria into the [[Biology:Central nervous system|central nervous system]]. When components of the bacterial [[Biology:Cell membrane|cell membrane]] are identified by the immune cells of the brain ([[Biology:Astrocyte|astrocyte]]s and [[Biology:Microglia|microglia]]), they respond by releasing large amounts of [[Biology:Cytokine|cytokine]]s, hormone-like mediators that recruit other immune cells and stimulate other tissues to participate in an immune response. The blood–brain barrier becomes more permeable, leading to [[Medicine:Cerebral edema#Vasogenic|"vasogenic" cerebral edema]] (swelling of the brain due to fluid leakage from blood vessels). Large numbers of [[Biology:White blood cell|white blood cell]]s enter the CSF, causing inflammation of the meninges and leading to [[Medicine:Cerebral edema#Interstitial Cerebral Edema|"interstitial" edema]] (swelling due to fluid between the cells). In addition, the walls of the blood vessels themselves become inflamed (cerebral vasculitis), which leads to decreased blood flow and a third type of edema, [[Medicine:Cerebral edema#Cytotoxic|"cytotoxic" edema]]. The three forms of cerebral edema all lead to increased [[Medicine:Intracranial pressure|intracranial pressure]]; together with the lowered blood pressure often encountered in [[Medicine:Sepsis|sepsis]], this means that it is harder for blood to enter the brain; consequently [[Biology:Brain cell|brain cell]]s are deprived of oxygen and undergo [[Biology:Apoptosis|apoptosis]] ([[Biology:Programmed cell death|programmed cell death]]).<ref name=Lancet/>

Administration of antibiotics may initially worsen the process outlined above, by increasing the amount of bacterial cell membrane products released through the destruction of bacteria. Particular treatments, such as the use of [[Chemistry:Glucocorticoid|corticosteroids]], are aimed at dampening the immune system's response to this phenomenon.<ref name=Lancet/><ref name=NEJM/>

==Diagnosis==
{| class="wikitable" style="float:right; font-size:85%; margin-left:15px;"
|+ CSF findings in different forms of meningitis<ref>{{Cite book |last1=Provan |first1=Drew |title=Oxford Handbook of Clinical and Laboratory Investigation |last2=Krentz |first2=Andrew |publisher=Oxford University Press |year=2005 |isbn=978-0-19-856663-2 |location=Oxford }}</ref>
|-
! Type of meningitis
! &nbsp;&nbsp;[[Biology:CSF glucose|Glucose]]&nbsp;&nbsp;
! Protein
! [[Biology:Pleocytosis|Cells]]
|-
! style="text-align: left;"| Acute bacterial
| low || high || [[Biology:Neutrophil|PMNs]],<br />often > 300/mm<sup>3</sup>
|-
! style="text-align: left;" | Acute viral
| normal || normal or high || [[Biology:Lymphocyte|mononuclear]],<br />< 300/mm<sup>3</sup>
|-
! style="text-align: left;" | Tuberculous
| low || high || mononuclear and<br />PMNs, < 300/mm<sup>3</sup>
|-
! style="text-align: left;" | Fungal
| low || high || < 300/mm<sup>3</sup>
|-
! style="text-align: left;" | [[Medicine:Neoplasm|Malignant]]
| low || high || usually<br />mononuclear
|}
Diagnosing meningitis as promptly as possible can improve outcomes.<ref name=":0">{{Cite journal |vauthors = Mount HR, Boyle SD |date=September 2017 |title=Aseptic and Bacterial Meningitis: Evaluation, Treatment, and Prevention |url=https://www.aafp.org/afp/2017/0901/p314.html |url-status=live |journal=American Family Physician |volume=96 |issue=5 |pages=314–322 |issn=0002-838X |pmid=28925647 |archive-url=https://web.archive.org/web/20201021093403/https://www.aafp.org/afp/2017/0901/p314.html |archive-date=21 October 2020 |access-date=18 October 2020}}</ref> There are no [[Medicine:Signs and symptoms#Cardinal|specific signs or symptoms]] that can indicate meningitis, and a [[Medicine:Lumbar puncture|lumbar puncture]] (spinal tap) to examine the cerebrospinal fluid is recommended for diagnosis.<ref name=":0" /> Lumbar puncture is contraindicated if there is a mass in the brain (tumor or abscess) or the [[Medicine:Intracranial pressure|intracranial pressure]] (ICP) is elevated, as it may lead to [[Medicine:Brain herniation|brain herniation]]. If someone is at risk for either a mass or raised ICP (recent head injury, a known immune system problem, localizing neurological signs, or evidence on examination of a raised ICP), a CT or [[Physics:Magnetic resonance imaging|MRI]] scan is recommended prior to the lumbar puncture.<ref name="IDSA" /><ref name="EFNS" /><ref name="BIS">{{cite journal|vauthors=Heyderman RS, Lambert HP, O'Sullivan I, Stuart JM, Taylor BL, Wall RA|date=February 2003|title=Early management of suspected bacterial meningitis and meningococcal septicaemia in adults|url=http://www.britishinfection.org/drupal/sites/default/files/meningitisJI2003.pdf|url-status=dead|journal=The Journal of Infection|volume=46|issue=2|pages=75–77|doi=10.1053/jinf.2002.1110|pmid=12634067|archive-url=https://web.archive.org/web/20110725103638/http://www.britishinfection.org/drupal/sites/default/files/meningitisJI2003.pdf|archive-date=25 July 2011}} – formal guideline at {{Cite web |date=December 2004 |title=Early management of suspected meningitis and meningococcal septicaemia in immunocompetent adults |url=http://www.meningitis.org/assets/x/51738 |url-status=live |archive-url=https://web.archive.org/web/20131019120524/http://www.meningitis.org/assets/x/51738 |archive-date=19 October 2013 |access-date=19 October 2008 |publisher=British Infection Society }}</ref> This applies in 45% of all adult cases.<ref name="NEJM" />

There are no physical tests that can rule out or determine if a person has meningitis.<ref name=":1">{{Cite journal |vauthors = Iguchi M, Noguchi Y, Yamamoto S, Tanaka Y, Tsujimoto H |date=June 2020 |title=Diagnostic test accuracy of jolt accentuation for headache in acute meningitis in the emergency setting |journal=The Cochrane Database of Systematic Reviews |volume=2020 |issue=6 |pages=CD012824 |doi=10.1002/14651858.CD012824.pub2 |issn=1469-493X |pmc=7386453 |pmid=32524581}}</ref> The jolt accentuation test is not specific or sensitive enough to completely rule out meningitis.<ref name=":1" />

If someone is suspected of having meningitis, [[Medicine:Blood test|blood test]]s are performed for markers of inflammation (e.g. [[Chemistry:C-reactive protein|C-reactive protein]], [[Medicine:Complete blood count|complete blood count]]), as well as [[Biology:Blood culture|blood culture]]s.<ref name="IDSA" /><ref name="EFNS">{{Cite journal |vauthors=Chaudhuri A, Martinez-Martin P, Martin PM, Kennedy PG, Andrew Seaton R, Portegies P, Bojar M, Steiner I |date=July 2008 |title=EFNS guideline on the management of community-acquired bacterial meningitis: report of an EFNS Task Force on acute bacterial meningitis in older children and adults |journal=European Journal of Neurology |volume=15 |issue=7 |pages=649–59 |doi=10.1111/j.1468-1331.2008.02193.x |pmid=18582342 | doi-access=free | title-link=doi |s2cid=12415715}}</ref> If a CT or MRI is required before LP, or if LP proves difficult, professional guidelines suggest that antibiotics should be administered first to prevent delay in treatment,<ref name=IDSA/> especially if this may be longer than 30&nbsp;minutes.<ref name=EFNS/><ref name=BIS/> Often, CT or MRI scans are performed at a later stage to assess for complications of meningitis.<ref name=Lancet/>

In severe forms of meningitis, monitoring of blood electrolytes may be important; for example, [[Medicine:Hyponatremia|hyponatremia]] is common in bacterial meningitis.<ref name=Mac2016/> The cause of hyponatremia, however, is controversial and may include dehydration, the inappropriate secretion of the antidiuretic hormone (SIADH), or overly aggressive [[Chemistry:Intravenous therapy|intravenous fluid administration]].<ref name=NEJM/><ref name="Mac2016">{{Cite journal |vauthors=Maconochie IK, Bhaumik S |date=November 2016 |title=Fluid therapy for acute bacterial meningitis |url=http://archive.lstmed.ac.uk/8112/1/Cochrane_Fluid%20therapy%20for%20acute%20bacterial%20meningitis.pdf |url-status=live |journal=The Cochrane Database of Systematic Reviews |volume=2016 |issue=11 |pages=CD004786 |doi=10.1002/14651858.CD004786.pub5 |pmc=6464853 |pmid=27813057 |archive-url=https://web.archive.org/web/20200804004938/http://archive.lstmed.ac.uk/8112/1/Cochrane_Fluid%20therapy%20for%20acute%20bacterial%20meningitis.pdf |archive-date=4 August 2020 |access-date=30 December 2018 |quote=Careful management of fluid and electrolyte balance is also important in the treatment of meningitis... there are different opinions regarding the cause of hyponatraemia... if dehydration, rather than inappropriately increased antidiuresis... fluid restriction is open to question}}</ref>

===Lumbar puncture===
[[File:MenigitisCSF2019.jpg|thumb|Cloudy CSF from a person with meningitis due to Streptococcus]]
[[File:Neisseria meningitidis.jpg|thumb|Gram stain of meningococci from a culture showing Gram negative (pink) bacteria, often in pairs]]
A lumbar puncture is done by positioning the person, usually lying on the side, applying [[Medicine:Local anesthetic|local anesthetic]], and inserting a needle into the dural sac (a sac around the spinal cord) to collect cerebrospinal fluid (CSF). When this has been achieved, the "opening pressure" of the CSF is measured using a manometer. The pressure is normally between 6&nbsp;and 18&nbsp;cm water (cmH<sub>2</sub>O);<ref name="Straus">{{Cite journal |vauthors=Straus SE, Thorpe KE, Holroyd-Leduc J |date=October 2006 |title=How do I perform a lumbar puncture and analyze the results to diagnose bacterial meningitis? |journal=JAMA |volume=296 |issue=16 |pages=2012–22 |doi=10.1001/jama.296.16.2012 |pmid=17062865 | doi-access=free | title-link=doi }}</ref> in bacterial meningitis the pressure is usually elevated.<ref name=IDSA/><ref name=EFNS/> In cryptococcal meningitis, intracranial pressure is markedly elevated.<ref name="Perfect2010">{{Cite journal |vauthors=Perfect JR, Dismukes WE, Dromer F, Goldman DL, Graybill JR, Hamill RJ, Harrison TS, Larsen RA, Lortholary O, Nguyen MH, Pappas PG, Powderly WG, Singh N, Sobel JD, Sorrell TC |date=February 2010 |title=Clinical practice guidelines for the management of cryptococcal disease: 2010 update by the infectious diseases society of america |url=http://cid.oxfordjournals.org/content/50/3/291.long |url-status=live |journal=Clinical Infectious Diseases |volume=50 |issue=3 |pages=291–322 |doi=10.1086/649858 |pmc=5826644 |pmid=20047480 |archive-url=https://web.archive.org/web/20120109115208/http://cid.oxfordjournals.org/content/50/3/291.long |archive-date=9 January 2012 }}</ref> The initial appearance of the fluid may prove an indication of the nature of the infection: cloudy CSF indicates higher levels of protein, white and red blood cells and/or bacteria, and therefore may suggest bacterial meningitis.<ref name=IDSA/>

The CSF sample is examined for presence and types of [[Biology:White blood cell|white blood cell]]s, [[Biology:Red blood cell|red blood cell]]s, [[Biology:Protein|protein]] content and [[Chemistry:Glucose|glucose]] level.<ref name=IDSA/> Gram staining of the sample may demonstrate bacteria in bacterial meningitis, but absence of bacteria does not exclude bacterial meningitis as they are only seen in 60% of cases; this figure is reduced by a further 20% if antibiotics were administered before the sample was taken. Gram staining is also less reliable in particular infections such as [[Medicine:Listeriosis|listeriosis]]. [[Biology:Microbiological culture|Microbiological culture]] of the sample is more sensitive (it identifies the organism in 70–85% of cases) but results can take up to 48&nbsp;hours to become available.<ref name=IDSA/> The type of white blood cell predominantly present (see table) indicates whether meningitis is bacterial (usually neutrophil-predominant) or viral (usually lymphocyte-predominant),<ref name=IDSA/> although at the beginning of the disease this is not always a reliable indicator. Less commonly, [[Biology:Eosinophil|eosinophil]]s predominate, suggesting parasitic or fungal etiology, among others.<ref name=Graeff/>

The concentration of glucose in CSF is normally above 40% of that in blood. In bacterial meningitis it is typically lower; the CSF glucose level is therefore divided by the blood glucose (CSF glucose to serum glucose ratio). A ratio ≤0.4 is indicative of bacterial meningitis;<ref name=Straus/> in the newborn, glucose levels in CSF are normally higher, and a ratio below 0.6 (60%) is therefore considered abnormal.<ref name=IDSA/> High levels of [[Chemistry:Lactic acid|lactate]] in CSF indicate a higher likelihood of bacterial meningitis, as does a higher white blood cell count.<ref name=Straus/> If lactate levels are less than 35&nbsp;mg/dl and the person has not previously received antibiotics then this may rule out bacterial meningitis.<ref>{{Cite journal |vauthors=Sakushima K, Hayashino Y, Kawaguchi T, Jackson JL, Fukuhara S |date=April 2011 |title=Diagnostic accuracy of cerebrospinal fluid lactate for differentiating bacterial meningitis from aseptic meningitis: a meta-analysis |journal=The Journal of Infection |volume=62 |issue=4 |pages=255–62 |doi=10.1016/j.jinf.2011.02.010 |pmid=21382412 |hdl-access=free |hdl=2115/48503 |s2cid=206172763}}</ref>

Various other specialized tests may be used to distinguish between different types of meningitis. A latex agglutination test may be positive in meningitis caused by ''[[Biology:Streptococcus pneumoniae|Streptococcus pneumoniae]]'', ''[[Biology:Neisseria meningitidis|Neisseria meningitidis]]'', ''[[Biology:Haemophilus influenzae|Haemophilus influenzae]]'', ''[[Biology:Escherichia coli|Escherichia coli]]'' and ''[[Biology:Streptococcus agalactiae|group B streptococci]]''; its routine use is not encouraged as it rarely leads to changes in treatment, but it may be used if other tests are not diagnostic. Similarly, the [[Chemistry:Limulus amebocyte lysate|limulus lysate test]] may be positive in meningitis caused by Gram-negative bacteria, but it is of limited use unless other tests have been unhelpful.<ref name=IDSA/> [[Biology:Polymerase chain reaction|Polymerase chain reaction]] (PCR) is a technique used to amplify small traces of bacterial DNA in order to detect the presence of bacterial or viral DNA in cerebrospinal fluid; it is a highly sensitive and specific test since only trace amounts of the infecting agent's DNA is required. It may identify bacteria in bacterial meningitis and may assist in distinguishing the various causes of viral meningitis ([[Biology:Enterovirus|enterovirus]], herpes simplex virus 2 and [[Medicine:Mumps|mumps]] in those not vaccinated for this).<ref name=LoganMacMahon/> [[Biology:Serology|Serology]] (identification of antibodies to viruses) may be useful in viral meningitis.<ref name=LoganMacMahon/> If tuberculous meningitis is suspected, the sample is processed for [[Physics:Ziehl–Neelsen stain|Ziehl–Neelsen stain]], which has a low sensitivity, and tuberculosis culture, which takes a long time to process; PCR is being used increasingly.<ref name=Tuberc/> Diagnosis of cryptococcal meningitis can be made at low cost using an India ink stain of the CSF; however, testing for cryptococcal antigen in blood or CSF is more sensitive.<ref name="BMB">{{Cite journal |vauthors=Bicanic T, Harrison TS |year=2004 |title=Cryptococcal meningitis |journal=British Medical Bulletin |volume=72 |issue=1 |pages=99–118 |doi=10.1093/bmb/ldh043 |pmid=15838017 | doi-access=free | title-link=doi }}</ref><ref name="Sloan2008">{{Cite journal |vauthors=Tenforde MW, Shapiro AE, Rouse B, Jarvis JN, Li T, Eshun-Wilson I, Ford N |date=July 2018 |title=Treatment for HIV-associated cryptococcal meningitis |journal=The Cochrane Database of Systematic Reviews |volume=2018 |issue=7 |pages=CD005647 |doi=10.1002/14651858.CD005647.pub3 |pmc=6513250 |pmid=30045416 |id=CD005647}}</ref>

A diagnostic and therapeutic difficulty is "partially treated meningitis", where there are meningitis symptoms after receiving antibiotics (such as for presumptive [[Medicine:Sinusitis|sinusitis]]). When this happens, CSF findings may resemble those of viral meningitis, but antibiotic treatment may need to be continued until there is definitive positive evidence of a viral cause (e.g. a positive enterovirus PCR).<ref name=LoganMacMahon/>

===Postmortem===
[[File:Meningitis Histopathology.jpg|thumb|Histopathology of bacterial meningitis: autopsy case of a person with pneumococcal meningitis showing inflammatory infiltrates of the pia mater consisting of neutrophil granulocytes (inset, higher magnification).]]
Meningitis can be diagnosed after death has occurred. The findings from a post mortem are usually a widespread inflammation of the pia mater and arachnoid layers of the meninges. Neutrophil granulocytes tend to have migrated to the cerebrospinal fluid and the base of the brain, along with cranial nerves and the [[Biology:Spinal cord|spinal cord]], may be surrounded with [[Medicine:Pus|pus]]&nbsp;– as may the meningeal vessels.<ref name="OTM1">{{Cite book |title=Oxford Textbook of Medicine Volume 3 |vauthors=Warrell DA, Farrar JJ, Crook DW |publisher=Oxford University Press |year=2003 |isbn=978-0-19-852787-9 |edition=Fourth |pages=1115–29 |chapter=24.14.1 Bacterial meningitis}}</ref>

==Prevention==
For some causes of meningitis, protection can be provided in the long term through [[Biology:Vaccination|vaccination]], or in the short term with [[Chemistry:Antibiotic|antibiotic]]s. Some behavioral measures may also be effective.

===Behavioral===
Bacterial and viral meningitis are contagious, but neither is as contagious as the [[Medicine:Common cold|common cold]] or flu.<ref name="CDCtransmission">{{Cite web |date=7 February 2022|title=Causes and How It Spreads |url=https://www.cdc.gov/meningococcal/about/causes-transmission.html |url-status=live |archive-url=https://web.archive.org/web/20110629041733/http://www.cdc.gov/meningitis/about/transmission.html |archive-date=29 June 2011 |access-date=18 June 2011 |publisher=U.S. Centers for Disease Control and Prevention (CDC)}}</ref> Both can be transmitted through droplets of respiratory secretions during close contact such as kissing, sneezing or coughing on someone,<ref name="CDCtransmission" /> but bacterial meningitis cannot be spread by only breathing the air where a person with meningitis has been. Viral meningitis is typically caused by enteroviruses, and is most commonly spread through fecal contamination.<ref name="CDCtransmission" /> The risk of infection can be decreased by changing the behavior that led to transmission.

===Vaccination===
Since the 1980s, many countries have included [[Medicine:Hib vaccine|immunization against ''Haemophilus influenzae'' type B]] in their routine childhood vaccination schemes. This has practically [[Biology:Eradication of infectious diseases|eliminated]] this pathogen as a cause of meningitis in young children in those countries. In the countries in which the disease burden is highest, however, the vaccine is still too expensive.<ref name="SegalPollard">{{Cite journal |vauthors=Segal S, Pollard AJ |year=2004 |title=Vaccines against bacterial meningitis |journal=British Medical Bulletin |volume=72 |issue=1 |pages=65–81 |doi=10.1093/bmb/ldh041 |pmid=15802609 | doi-access=free | title-link=doi }}</ref><ref name="Peltola">{{Cite journal |vauthors=Peltola H |date=April 2000 |title=Worldwide Haemophilus influenzae type b disease at the beginning of the 21st century: global analysis of the disease burden 25 years after the use of the polysaccharide vaccine and a decade after the advent of conjugates |journal=Clinical Microbiology Reviews |volume=13 |issue=2 |pages=302–17 |doi=10.1128/CMR.13.2.302-317.2000 |pmc=100154 |pmid=10756001 }}</ref> Similarly, immunization against mumps has led to a sharp fall in the number of cases of mumps meningitis, which prior to vaccination occurred in 15% of all cases of mumps.<ref name=LoganMacMahon/>

[[Medicine:Meningococcal vaccine|Meningococcus vaccines]] exist against groups A, B, C, W135 and Y.<ref name="Harrison">{{Cite journal |vauthors=Harrison LH |date=January 2006 |title=Prospects for vaccine prevention of meningococcal infection |journal=Clinical Microbiology Reviews |volume=19 |issue=1 |pages=142–64 |doi=10.1128/CMR.19.1.142-164.2006 |pmc=1360272 |pmid=16418528 }}</ref><ref name="bexsero">{{Cite web |title=A new MenB (meningococcal B) vaccine |url=http://www.meningitis.org/menb-vaccine |url-status=dead |archive-url=https://web.archive.org/web/20141129191130/http://www.meningitis.org/menb-vaccine |archive-date=29 November 2014 |access-date=23 November 2014 |publisher=Meningitis Research Foundation}}</ref><ref name="trumenba">{{Cite press release |date=29 October 2014 |title=First vaccine approved by FDA to prevent serogroup B Meningococcal disease |url=https://www.fda.gov/news-events/press-announcements/first-vaccine-approved-fda-prevent-serogroup-b-meningococcal-disease |url-status=live |archive-url=https://web.archive.org/web/20141116092407/https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm420998.htm |archive-date=16 November 2014 |publisher=U.S. [[Organization:Food and Drug Administration|Food and Drug Administration]] (FDA) }}</ref> In countries where the vaccine for meningococcus group C was introduced, cases caused by this pathogen have decreased substantially.<ref name=SegalPollard/> A quadrivalent vaccine now exists, which combines four vaccines with the exception of B; immunization with this ACW135Y vaccine is now a visa requirement for taking part in [[Religion:Hajj|Hajj]].<ref name=WilderSmith/> Development of a vaccine against group B meningococci has proved much more difficult, as its surface proteins (which would normally be used to make a vaccine) only elicit a weak [[Biology:Immunogenicity|response from the immune system]], or cross-react with normal human proteins.<ref name=SegalPollard/><ref name=Harrison/> Still, some countries ([[Earth:New Zealand|New Zealand]], Cuba, {{wipe|Norway}} and {{wipe|Chile}}) have developed vaccines against local strains of group B meningococci; some have shown good results and are used in local immunization schedules.<ref name=Harrison/> Two new vaccines, both approved in 2014, are effective against a wider range of group B meningococci strains.<ref name=bexsero/><ref name=trumenba/> In Africa, until recently, the approach for prevention and control of meningococcal epidemics was based on early detection of the disease and emergency reactive mass vaccination of the at-risk population with bivalent A/C or trivalent A/C/W135 polysaccharide vaccines,<ref>{{Cite journal |vauthors=((World Health Organization)) |date=September 2000 |title=Detecting meningococcal meningitis epidemics in highly-endemic African countries |journal=Weekly Epidemiological Record |volume=75 |issue=38 |pages=306–309 |pmid=11045076 | hdl=10665/231278 | hdl-access=free | author-link=World Health Organization }}</ref> though the introduction of MenAfriVac (meningococcus group A vaccine) has demonstrated effectiveness in young people and has been described as a model for product development partnerships in resource-limited settings.<ref>{{Cite journal |vauthors=Bishai DM, Champion C, Steele ME, Thompson L |date=June 2011 |title=Product development partnerships hit their stride: lessons from developing a meningitis vaccine for Africa |journal=Health Affairs |volume=30 |issue=6 |pages=1058–64 |doi=10.1377/hlthaff.2011.0295 |pmid=21653957}}</ref><ref>{{Cite journal |vauthors=Marc LaForce F, Ravenscroft N, Djingarey M, Viviani S |date=June 2009 |title=Epidemic meningitis due to Group A Neisseria meningitidis in the African meningitis belt: a persistent problem with an imminent solution |journal=Vaccine |volume=27 |issue=Suppl 2 |pages=B13–19 |doi=10.1016/j.vaccine.2009.04.062 |pmid=19477559}}</ref>

Routine vaccination against ''Streptococcus pneumoniae'' with the [[Medicine:Pneumococcal conjugate vaccine|pneumococcal conjugate vaccine]] (PCV), which is active against seven common serotypes of this pathogen, significantly reduces the incidence of pneumococcal meningitis.<ref name=SegalPollard/><ref name="Weisfelt">{{Cite journal |vauthors=Weisfelt M, de Gans J, van der Poll T, van de Beek D |date=April 2006 |title=Pneumococcal meningitis in adults: new approaches to management and prevention |journal=The Lancet. Neurology |volume=5 |issue=4 |pages=332–42 |doi=10.1016/S1474-4422(06)70409-4 |pmid=16545750 |s2cid=19318114}}</ref> The [[Medicine:Pneumococcal polysaccharide vaccine|pneumococcal polysaccharide vaccine]], which covers 23 strains, is only administered to certain groups (e.g. those who have had a [[Medicine:Splenectomy|splenectomy]], the surgical removal of the spleen); it does not elicit a significant immune response in all recipients, e.g. small children.<ref name=Weisfelt/> Childhood vaccination with Bacillus Calmette-Guérin has been reported to significantly reduce the rate of tuberculous meningitis, but its waning effectiveness in adulthood has prompted a search for a better vaccine.<ref name=SegalPollard/>

===Antibiotics===
Short-term antibiotic prophylaxis is another method of prevention, particularly of meningococcal meningitis. In cases of meningococcal meningitis, preventative treatment in close contacts with antibiotics (e.g. [[Chemistry:Rifampicin|rifampicin]], [[Chemistry:Ciprofloxacin|ciprofloxacin]] or [[Chemistry:Ceftriaxone|ceftriaxone]]) can reduce their risk of contracting the condition, but does not protect against future infections.<ref name=EFNS/><ref name="Zal2013">{{Cite journal |vauthors=Zalmanovici Trestioreanu A, Fraser A, Gafter-Gvili A, Paul M, Leibovici L |date=October 2013 |title=Antibiotics for preventing meningococcal infections |journal=The Cochrane Database of Systematic Reviews |volume=10 |issue=10 |pages=CD004785 |doi=10.1002/14651858.CD004785.pub5 |pmc=6698485 |pmid=24163051}}</ref> Resistance to rifampicin has been noted to increase after use, which has caused some to recommend considering other agents.<ref name=Zal2013/> While antibiotics are frequently used in an attempt to prevent meningitis in those with a [[Medicine:Basilar skull fracture|basilar skull fracture]] there is not enough evidence to determine whether this is beneficial or harmful.<ref name="CochSk2015">{{Cite journal |vauthors=Ratilal BO, Costa J, Pappamikail L, Sampaio C |date=April 2015 |title=Antibiotic prophylaxis for preventing meningitis in patients with basilar skull fractures |journal=The Cochrane Database of Systematic Reviews |volume=2015 |issue=4 |pages=CD004884 |doi=10.1002/14651858.CD004884.pub4 |pmid=25918919|pmc=10554555 }}</ref> This applies to those with or without a CSF leak.<ref name=CochSk2015/>

==Management==
Meningitis is potentially life-threatening and has a high mortality rate if untreated;<ref name=IDSA/> delay in treatment has been associated with a poorer outcome.<ref name=NEJM/> Thus, treatment with wide-spectrum antibiotics should not be delayed while confirmatory tests are being conducted.<ref name=BIS/> If meningococcal disease is suspected in primary care, guidelines recommend that [[Chemistry:Benzylpenicillin|benzylpenicillin]] be administered before transfer to hospital.<ref name=SIGN/> Intravenous fluids should be administered if [[Medicine:Hypotension|hypotension]] (low blood pressure) or [[Medicine:Shock (circulatory)|shock]] are present.<ref name=BIS/> It is not clear whether intravenous fluid should be given routinely or whether this should be restricted.<ref>{{Cite journal |vauthors=Maconochie IK, Bhaumik S |date=November 2016 |title=Fluid therapy for acute bacterial meningitis |url=http://archive.lstmed.ac.uk/8112/1/Cochrane_Fluid%20therapy%20for%20acute%20bacterial%20meningitis.pdf |url-status=live |journal=The Cochrane Database of Systematic Reviews |volume=2016 |issue=11 |pages=CD004786 |doi=10.1002/14651858.CD004786.pub5 |pmc=6464853 |pmid=27813057 |archive-url=https://web.archive.org/web/20200804004938/http://archive.lstmed.ac.uk/8112/1/Cochrane_Fluid%20therapy%20for%20acute%20bacterial%20meningitis.pdf |archive-date=4 August 2020 |access-date=30 December 2018}}</ref> Given that meningitis can cause a number of early severe complications, regular medical review is recommended to identify these complications early<ref name=BIS/> and to admit the person to an [[Medicine:Intensive care unit|intensive care unit]] if deemed necessary.<ref name=NEJM/>

[[Medicine:Mechanical ventilation|Mechanical ventilation]] may be needed if the level of consciousness is very low, or if there is evidence of [[Medicine:Respiratory failure|respiratory failure]]. If there are signs of raised intracranial pressure, measures to monitor the pressure may be taken; this would allow the optimization of the [[Biology:Cerebral perfusion pressure|cerebral perfusion pressure]] and various treatments to decrease the intracranial pressure with medication (e.g. [[Chemistry:Mannitol|mannitol]]).<ref name=NEJM/> Seizures are treated with [[Chemistry:Anticonvulsant|anticonvulsant]]s.<ref name=NEJM/> Hydrocephalus (obstructed flow of CSF) may require insertion of a temporary or long-term drainage device, such as a [[Medicine:Cerebral shunt|cerebral shunt]].<ref name=NEJM/> The osmotic therapy, [[Chemistry:Glycerol|glycerol]], has an unclear effect on mortality but may decrease hearing problems.<ref>{{Cite journal |vauthors=Wall EC, Ajdukiewicz KM, Bergman H, Heyderman RS, Garner P |date=February 2018 |title=Osmotic therapies added to antibiotics for acute bacterial meningitis |journal=The Cochrane Database of Systematic Reviews |volume=2018 |issue=2 |pages=CD008806 |doi=10.1002/14651858.CD008806.pub3 |pmc=5815491 |pmid=29405037}}</ref>

===Bacterial meningitis===

====Antibiotics====
[[File:Ceftriaxone structure.png|thumb|Structural formula of ceftriaxone, one of the third-generation cefalosporin antibiotics recommended for the initial treatment of bacterial meningitis.]]

Empiric antibiotics (treatment without exact diagnosis) should be started immediately, even before the results of the lumbar puncture and CSF analysis are known. The choice of initial treatment depends largely on the kind of bacteria that cause meningitis in a particular place and population. For instance, in the United Kingdom, empirical treatment consists of a third-generation cefalosporin such as [[Chemistry:Cefotaxime|cefotaxime]] or [[Chemistry:Ceftriaxone|ceftriaxone]].<ref name=EFNS/><ref name=BIS/> In the US, where resistance to cefalosporins is increasingly found in streptococci, addition of [[Chemistry:Vancomycin|vancomycin]] to the initial treatment is recommended.<ref name=NEJM/><ref name=IDSA/><ref name=EFNS/> [[Chemistry:Chloramphenicol|Chloramphenicol]], either alone or in combination with [[Chemistry:Ampicillin|ampicillin]], however, appears to work equally well.<ref>{{Cite journal |vauthors=Prasad K, Kumar A, Gupta PK, Singhal T |date=October 2007 |veditors=Prasad K |title=Third generation cephalosporins versus conventional antibiotics for treating acute bacterial meningitis |journal=The Cochrane Database of Systematic Reviews |volume=2007 |issue=4 |pages=CD001832 |doi=10.1002/14651858.CD001832.pub3 |pmc=8078560 |pmid=17943757}}</ref>

Empirical therapy may be chosen on the basis of the person's age, whether the infection was preceded by a [[Medicine:Head injury|head injury]], whether the person has undergone recent [[Medicine:Neurosurgery|neurosurgery]] and whether or not a cerebral shunt is present.<ref name=IDSA/> In young children and those over 50&nbsp;years of age, as well as those who are immunocompromised, the addition of [[Chemistry:Ampicillin|ampicillin]] is recommended to cover ''[[Biology:Listeria monocytogenes|Listeria monocytogenes]]''.<ref name=IDSA/><ref name=EFNS/> Once the Gram stain results become available, and the broad type of bacterial cause is known, it may be possible to change the antibiotics to those likely to deal with the presumed group of pathogens.<ref name=IDSA/> The results of the CSF [[Biology:Microbiological culture|culture]] generally take longer to become available (24–48 hours). Once they do, empiric therapy may be switched to specific antibiotic therapy targeted to the specific causative organism and its sensitivities to antibiotics.<ref name=IDSA/> For an antibiotic to be effective in meningitis it must not only be active against the pathogenic bacterium but also reach the meninges in adequate quantities; some antibiotics have inadequate penetrance and therefore have little use in meningitis. Most of the antibiotics used in meningitis have not been tested directly on people with meningitis in [[Engineering:Clinical trial|clinical trial]]s. Rather, the relevant knowledge has mostly derived from laboratory studies in [[Biology:Rabbit|rabbit]]s.<ref name=IDSA/> Tuberculous meningitis requires prolonged treatment with antibiotics. While tuberculosis of the lungs is typically treated for six months, those with tuberculous meningitis are typically treated for a year or longer.<ref name=Tuberc/>

==== Fluid Therapy ====
Fluid given intravenously are an essential part of treatment of bacterial meningitis. There is no difference in terms of mortality or acute severe neurological complications in children given a maintenance regimen over restricted-fluid regimen, but evidence is in favor of the maintenance regimen in terms of emergence of chronic severe neurological complications.<ref>{{Cite journal |vauthors = Maconochie IK, Bhaumik S |date=November 2016 |title=Fluid therapy for acute bacterial meningitis |journal=The Cochrane Database of Systematic Reviews |volume=2016 |issue=11 |pages=CD004786 |doi=10.1002/14651858.CD004786.pub5 |issn=1469-493X |pmc=6464853 |pmid=27813057}}</ref>

====Steroids====
Additional treatment with corticosteroids (usually [[Biology:Dexamethasone|dexamethasone]]) has shown some benefits, such as a reduction of [[Medicine:Hearing loss|hearing loss]], and better short term neurological outcomes<ref name="CochDex2013">{{Cite journal |vauthors=Brouwer MC, McIntyre P, Prasad K, van de Beek D |date=September 2015 |title=Corticosteroids for acute bacterial meningitis |journal=The Cochrane Database of Systematic Reviews |volume=2015 |issue=9 |pages=CD004405 |doi=10.1002/14651858.CD004405.pub5 |pmc=6491272 |pmid=26362566}}</ref> in adolescents and adults from [[Finance:World Bank high-income economy|high-income countries]] with low rates of HIV.<ref name="Assiri2009">{{Cite journal |vauthors=Assiri AM, Alasmari FA, Zimmerman VA, Baddour LM, Erwin PJ, Tleyjeh IM |date=May 2009 |title=Corticosteroid administration and outcome of adolescents and adults with acute bacterial meningitis: a meta-analysis |journal=Mayo Clinic Proceedings |volume=84 |issue=5 |pages=403–09 |doi=10.4065/84.5.403 |pmc=2676122 |pmid=19411436}}</ref> Some research has found reduced rates of death<ref name=Assiri2009/> while other research has not.<ref name=CochDex2013/> They also appear to be beneficial in those with tuberculosis meningitis, at least in those who are HIV negative.<ref>{{Cite journal |vauthors=Prasad K, Singh MB, Ryan H |date=April 2016 |title=Corticosteroids for managing tuberculous meningitis |journal=The Cochrane Database of Systematic Reviews |volume=2016 |issue=4 |pages=CD002244 |doi=10.1002/14651858.CD002244.pub4 |pmc=4916936 |pmid=27121755}}</ref>

Professional guidelines therefore recommend the commencement of dexamethasone or a similar corticosteroid just before the first dose of antibiotics is given, and continued for four&nbsp;days.<ref name=EFNS/><ref name=BIS/> Given that most of the benefit of the treatment is confined to those with pneumococcal meningitis, some guidelines suggest that dexamethasone be discontinued if another cause for meningitis is identified.<ref name=IDSA/><ref name=EFNS/> The likely mechanism is suppression of overactive inflammation.<ref name="deGans2002">{{Cite journal |vauthors=de Gans J, van de Beek D |date=November 2002 |title=Dexamethasone in adults with bacterial meningitis |url=http://dare.uva.nl/personal/pure/en/publications/dexamethasone-in-adults-with-bacterial-meningitis(72435a94-1ea1-488f-9407-345b79b068cc).html |url-status=live |journal=The New England Journal of Medicine |volume=347 |issue=20 |pages=1549–56 |doi=10.1056/NEJMoa021334 |pmid=12432041 |archive-url=https://web.archive.org/web/20210829150418/https://dare.uva.nl/search?identifier=72435a94-1ea1-488f-9407-345b79b068cc |archive-date=29 August 2021 |access-date=20 October 2018 |s2cid=72596402| doi-access=free | title-link=doi }}</ref>

Additional treatment with corticosteroids have a different role in children than in adults. Though the benefit of corticosteroids has been demonstrated in adults as well as in children from high-income countries, their use in children from low-income countries is not supported by the evidence; the reason for this discrepancy is not clear.<ref name=CochDex2013/> Even in high-income countries, the benefit of corticosteroids is only seen when they are given prior to the first dose of antibiotics, and is greatest in cases of ''H. influenzae'' meningitis,<ref name=IDSA/><ref name="pmid9302246">{{Cite journal |vauthors=McIntyre PB, Berkey CS, King SM, Schaad UB, Kilpi T, Kanra GY, Perez CM |date=September 1997 |title=Dexamethasone as adjunctive therapy in bacterial meningitis. A meta-analysis of randomized clinical trials since 1988 |journal=JAMA |volume=278 |issue=11 |pages=925–31 |doi=10.1001/jama.1997.03550110063038 |pmid=9302246}}</ref> the incidence of which has decreased dramatically since the introduction of the [[Medicine:Hib vaccine|Hib vaccine]]. Thus, corticosteroids are recommended in the treatment of pediatric meningitis if the cause is ''H. influenzae'', and only if given prior to the first dose of antibiotics; other uses are controversial.<ref name=IDSA/>

==== Adjuvant therapies ====
In addition to the primary therapy of antibiotics and corticosteroids, other adjuvant therapies are under development or are sometimes used to try and improve survival from bacterial meningitis and reduce the risk of neurological problems. Examples of adjuvant therapies that have been trialed include [[Chemistry:Paracetamol|acetaminophe]]<nowiki/>n, [[Medicine:Immunoglobulin therapy|immunoglobulin therapy]], [[Chemistry:Heparin|heparin]], [[Chemistry:Pentoxifylline|pentoxifyline]], and a mononucleotide mixture with [[Chemistry:Succinic acid|succinic acid]].<ref name=":2">{{Cite journal |vauthors = Fisher J, Linder A, Calevo MG, Bentzer P |date=November 2021 |title=Non-corticosteroid adjuvant therapies for acute bacterial meningitis |url= |journal=The Cochrane Database of Systematic Reviews |volume=2021 |issue=11 |pages=CD013437 |doi=10.1002/14651858.CD013437.pub2 |issn=1469-493X |pmc=8610076 |pmid=34813078}}</ref> It is not clear if any of these therapies are helpful or worsen outcomes in people with acute bacterial meningitis.<ref name=":2" />

===Viral meningitis===
Viral meningitis typically only requires supportive therapy; most viruses responsible for causing meningitis are not amenable to specific treatment. Viral meningitis tends to run a more benign course than bacterial meningitis. Herpes simplex virus and varicella zoster virus may respond to treatment with antiviral drugs such as [[Chemistry:Aciclovir|aciclovir]], but there are no clinical trials that have specifically addressed whether this treatment is effective.<ref name=LoganMacMahon/> Mild cases of viral meningitis can be treated at home with conservative measures such as fluid, bedrest, and analgesics.<ref>{{Cite web |date=11 December 2007 |title=Meningitis and Encephalitis Fact Sheet |url=http://www.ninds.nih.gov/disorders/encephalitis_meningitis/detail_encephalitis_meningitis.htm |url-status=live |archive-url=https://web.archive.org/web/20140104212119/http://www.ninds.nih.gov/disorders/encephalitis_meningitis/detail_encephalitis_meningitis.htm |archive-date=4 January 2014 |access-date=27 April 2009 |publisher=National Institute of Neurological Disorders and Stroke (NINDS)}}</ref>

===Fungal meningitis===
Fungal meningitis, such as cryptococcal meningitis, is treated with long courses of high dose antifungals, such as [[Chemistry:Amphotericin B|amphotericin B]] and [[Chemistry:Flucytosine|flucytosine]].<ref name=BMB/><ref>{{Cite journal |vauthors=Gottfredsson M, Perfect JR |year=2000 |title=Fungal meningitis |journal=Seminars in Neurology |volume=20 |issue=3 |pages=307–22 |doi=10.1055/s-2000-9394 |pmid=11051295|s2cid=37046726 }}</ref> Raised intracranial pressure is common in fungal meningitis, and frequent (ideally daily) lumbar punctures to relieve the pressure are recommended,<ref name=BMB/> or alternatively a lumbar drain.<ref name=Perfect2010/>

==Prognosis==
[[File:Meningitis world map - DALY - WHO2004.svg|thumb|upright=1.3|Disability-adjusted life year for meningitis per 100,000&nbsp;inhabitants in 2004.<ref>{{Cite web |year=2002 |title=Mortality and Burden of Disease Estimates for WHO Member States in 2002 |url=https://www.who.int/entity/healthinfo/statistics/bodgbddeathdalyestimates.xls |url-status=live |archive-url=https://web.archive.org/web/20130116174540/http://www.who.int/healthinfo/statistics/bodgbddeathdalyestimates.xls |archive-date=16 January 2013 |publisher=[[Organization:World Health Organization|World Health Organization]] (WHO) |format=xls}}</ref>
{{legend-col
|{{legend|#b3b3b3|no data}}
|{{legend|#ffff65|<10}}
|{{legend|#fff200|10–25}}
|{{legend|#ffdc00|25–50}}
|{{legend|#ffc600|50–75}}
|{{legend|#ffb000|75–100}}
|{{legend|#ff9a00|100–200}}
|{{legend|#ff8400|200–300}}
|{{legend|#ff6e00|300–400}}
|{{legend|#ff5800|400–500}}
|{{legend|#ff4200|500–750}}
|{{legend|#ff2c00|750–1000}}
|{{legend|#cb0000|>1000}}
}}]]
Untreated, bacterial meningitis is almost always fatal. According to the WHO bacterial meningitis has an overall mortality rate of 16.7% (with treatment).<ref name=WHO2023>{{Cite web |title=Meningitis |url=https://www.who.int/news-room/fact-sheets/detail/meningitis |access-date=30 May 2023 |publisher=[[Organization:World Health Organization|World Health Organization]] (WHO) |archive-date=10 January 2022 |archive-url=https://web.archive.org/web/20220110173749/https://www.who.int/news-room/fact-sheets/detail/meningitis |url-status=live }}</ref> Viral meningitis, in contrast, tends to resolve spontaneously and is rarely fatal. With treatment, [[Mortality rate|mortality]] (risk of death) from bacterial meningitis depends on the age of the person and the underlying cause. Of newborns, 20–30% may die from an episode of bacterial meningitis. This risk is much lower in older children, whose mortality is about 2%, but rises again to about 19–37% in adults.<ref name=Lancet/><ref name=NEJM/>

Risk of death is predicted by various factors apart from age, such as the pathogen and the time it takes for the pathogen to be cleared from the cerebrospinal fluid,<ref name=Lancet/> the severity of the generalized illness, a decreased level of consciousness or an abnormally low count of white blood cells in the CSF.<ref name=NEJM/> Meningitis caused by ''H.&nbsp;influenzae'' and meningococci has a better prognosis than cases caused by group B streptococci, coliforms and ''S. pneumoniae''.<ref name=Lancet/> In adults, too, meningococcal meningitis has a lower mortality (3–7%) than pneumococcal disease.<ref name=NEJM/>

In children there are several potential disabilities which may result from damage to the nervous system, including sensorineural hearing loss, [[Medicine:Epilepsy|epilepsy]], [[Medicine:Learning disability|learning]] and behavioral difficulties, as well as [[Medicine:Intellectual disability|decreased intelligence]].<ref name=Lancet/> These occur in about 15% of survivors.<ref name=Lancet/> Some of the hearing loss may be reversible.<ref name="pmid9068303">{{Cite journal |vauthors=Richardson MP, Reid A, Tarlow MJ, Rudd PT |date=February 1997 |title=Hearing loss during bacterial meningitis |journal=Archives of Disease in Childhood |volume=76 |issue=2 |pages=134–38 |doi=10.1136/adc.76.2.134 |pmc=1717058 |pmid=9068303 }}</ref> In adults, 66% of all cases emerge without disability. The main problems are [[Medicine:Deafness|deafness]] (in 14%) and [[Social:Developmental disability|cognitive impairment]] (in 10%).<ref name=NEJM/>

Tuberculous meningitis in children continues to be associated with a significant risk of death even with treatment (19%), and a significant proportion of the surviving children have ongoing neurological problems. Just over a third of all cases survives with no problems.<ref name="Chiang2014">{{Cite journal |vauthors=Chiang SS, Khan FA, Milstein MB, Tolman AW, Benedetti A, Starke JR, Becerra MC |date=October 2014 |title=Treatment outcomes of childhood tuberculous meningitis: a systematic review and meta-analysis |journal=The Lancet. Infectious Diseases |volume=14 |issue=10 |pages=947–57 |doi=10.1016/S1473-3099(14)70852-7 |pmid=25108337}}</ref>

==Epidemiology==
[[File:Meningitis-Epidemics-World-Map.png|right|thumb|upright=1.3|Demography of meningococcal meningitis.{{legend|#FF0000|meningitis belt}}{{legend|#E08040|epidemic zones}}{{legend|#C0C0C0|sporadic cases only}}]]
[[File:Meningitis world map-Deaths per million persons-WHO2012.svg|thumb|upright=1.3|Deaths from meningitis per million people in 2012 {{legend-col|thumb size=wide|{{legend|#ffff20|0–2}}|{{legend|#ffe820|3-3}}|{{legend|#ffd820|4–6}}|{{legend|#ffc020|7–9}}|{{legend|#ffa020|10–20}}|{{legend|#ff9a20|21–31}}|{{legend|#f08015|32–61}}|{{legend|#e06815|62–153}}|{{legend|#d85010|154–308}}|{{legend|#d02010|309–734}}}}]]
Although meningitis is a [[Medicine:Notifiable disease|notifiable disease]] in many countries, the exact [[Medicine:Incidence (epidemiology)|incidence]] rate is unknown.<ref name=LoganMacMahon/> In 2013 meningitis resulted in 303,000 deaths – down from 464,000 deaths in 1990.<ref name="GBD204">{{Cite journal |vauthors=((GBD 2013 Mortality Causes of Death Collaborators)) |date=January 2015 |title=Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013 |journal=Lancet |volume=385 |issue=9963 |pages=117–71 |doi=10.1016/S0140-6736(14)61682-2 |pmc=4340604 |pmid=25530442}}</ref> In 2010 it was estimated that meningitis resulted in 420,000 deaths,<ref name="Loz2012">{{Cite journal |vauthors=Lozano R, Naghavi M, Foreman K, et al |date=December 2012 |title=Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010 |url=https://zenodo.org/record/2557786 |url-status=live |journal=Lancet |volume=380 |issue=9859 |pages=2095–128 |doi=10.1016/S0140-6736(12)61728-0 |pmid=23245604 |pmc=10790329 |archive-url=https://web.archive.org/web/20200519152712/https://zenodo.org/record/2557786 |archive-date=19 May 2020 |access-date=23 March 2020 |hdl-access=free |hdl=10536/DRO/DU:30050819 |s2cid=1541253}}</ref> excluding cryptococcal meningitis.<ref name="ReferenceA" />

Bacterial meningitis occurs in about 3 people per 100,000 annually in Western countries. Population-wide studies have shown that viral meningitis is more common, at 10.9 per 100,000, and occurs more often in the summer. In Brazil, the rate of bacterial meningitis is higher, at 45.8 per 100,000 annually.<ref name=Attia/> [[Place:Sub-Saharan Africa|Sub-Saharan Africa]] has been plagued by large epidemics of meningococcal meningitis for over a century,<ref>{{Cite journal |vauthors=Lapeyssonnie L |year=1963 |title=Cerebrospinal Meningitis in Africa |journal=Bulletin of the World Health Organization |volume=28 Suppl |issue=Suppl |pages=1–114 |pmc=2554630 |pmid=14259333}}</ref> leading to it being labeled the "meningitis belt". Epidemics typically occur in the dry season (December to June), and an epidemic wave can last two to three years, dying out during the intervening rainy seasons.<ref>{{Cite journal |vauthors=Greenwood B |year=1999 |title=Manson Lecture. Meningococcal meningitis in Africa |journal=Transactions of the Royal Society of Tropical Medicine and Hygiene |volume=93 |issue=4 |pages=341–53 |doi=10.1016/S0035-9203(99)90106-2 |pmid=10674069}}</ref> Attack rates of 100–800 cases per 100,000 are encountered in this area,<ref name=WHO1998>{{Cite book |author=World Health Organization |url=https://www.who.int/csr/resources/publications/meningitis/whoemcbac983.pdf |title=Control of epidemic meningococcal disease, practical guidelines, 2nd edition, WHO/EMC/BA/98 |year=1998 |volume=3 |pages=1–83 |archive-url=https://web.archive.org/web/20131030051853/http://www.who.int/csr/resources/publications/meningitis/whoemcbac983.pdf |archive-date=30 October 2013 |url-status=live }} <!--No ISBN--></ref> which is poorly served by [[Medicine:Health care|medical care]]. These cases are predominantly caused by meningococci.<ref name=Attia/> The largest epidemic ever recorded in history swept across the entire region in 1996–1997, causing over 250,000 cases and 25,000 deaths.<ref>{{Cite journal |vauthors=((World Health Organization)) |date=August 2003 |title=Meningococcal meningitis : Overview |journal=Weekly Epidemiological Record |volume=78 |issue=33 |pages=294–296 |pmid=14509123 |hdl=10665/232232 | hdl-access=free }}</ref>

Meningococcal disease occurs in epidemics in areas where many people live together for the first time, such as army barracks during mobilization, university and college campuses<ref name=Lancet/> and the annual [[Religion:Hajj|Hajj]] pilgrimage.<ref name="WilderSmith">{{Cite journal |vauthors=Wilder-Smith A |date=October 2007 |title=Meningococcal vaccine in travelers |journal=Current Opinion in Infectious Diseases |volume=20 |issue=5 |pages=454–60 |doi=10.1097/QCO.0b013e3282a64700 |pmid=17762777 |s2cid=9411482}}</ref> Although the pattern of epidemic cycles in Africa is not well understood, several factors have been associated with the development of epidemics in the meningitis belt. They include: medical conditions (immunological susceptibility of the population), demographic conditions (travel and large population displacements), socioeconomic conditions (overcrowding and poor living conditions), climatic conditions (drought and dust storms), and concurrent infections (acute respiratory infections).<ref name=WHO1998/>

There are significant differences in the local distribution of causes for bacterial meningitis. For instance, while ''N. meningitides'' groups B and C cause most disease episodes in Europe, group A is found in Asia and continues to predominate in Africa, where it causes most of the major epidemics in the meningitis belt, accounting for about 80% to 85% of documented meningococcal meningitis cases.<ref name=WHO1998/>

==History==
Some suggest that [[Biography:Hippocrates|Hippocrates]] may have realized the existence of meningitis,<ref name=Attia/> and it seems that meningism was known to pre-Renaissance physicians such as [[Biography:Avicenna|Avicenna]].<ref name="Walker">{{Cite book |last1=Walker |first1=Arthur Earl |title=The Genesis of Neuroscience |last2=Laws |first2=Edward R. |last3=Udvarhelyi |first3=George B. |publisher=Thieme |year=1998 |isbn=978-1-879284-62-3 |pages=219–21 |chapter=Infections and inflammatory involvement of the CNS |access-date=24 August 2020 |chapter-url=https://books.google.com/books?id=UaSaRzw8gYEC&pg=PP1 |archive-url=https://web.archive.org/web/20220304053043/https://books.google.com/books?id=UaSaRzw8gYEC&pg=PP1 |archive-date=4 March 2022 |url-status=live }}</ref> The description of tuberculous meningitis, then called "dropsy in the brain", is often attributed to Edinburgh physician Sir Robert Whytt in a posthumous report that appeared in 1768, although the link with tuberculosis and its pathogen was not made until the next century.<ref name=Walker/><ref>{{Cite book |vauthors=Whytt R |title=Observations on the Dropsy in the Brain |publisher=J. Balfour |year=1768 |location=Edinburgh}}</ref>

It appears that epidemic meningitis is a relatively recent phenomenon.<ref name="Greenwood">{{Cite journal |vauthors=Greenwood B |date=June 2006 |title=Editorial: 100 years of epidemic meningitis in West Africa – has anything changed? |journal=Tropical Medicine & International Health |volume=11 |issue=6 |pages=773–80 |doi=10.1111/j.1365-3156.2006.01639.x |pmid=16771997 |s2cid=28838510}}</ref> The first recorded major outbreak occurred in [[Place:Geneva|Geneva]] in 1805.<ref name=Greenwood/><ref>{{Cite journal |vauthors=Vieusseux G |year=1806 |title=Mémoire sur le Maladie qui a regne à Génève au printemps de 1805 |journal=Journal de Médecine, de Chirurgie et de Pharmacologie (Bruxelles) |language=fr |volume=11 |pages=50–53}}</ref> Several other epidemics in Europe and the United States were described shortly afterward, and the first report of an epidemic in Africa appeared in 1840. African epidemics became much more common in the 20th&nbsp;century, starting with a major epidemic sweeping Nigeria and Ghana in 1905–1908.<ref name=Greenwood/>

The first report of bacterial infection underlying meningitis was by the Austrian bacteriologist [[Biography:Anton Weichselbaum|Anton Weichselbaum]], who in 1887 described the ''meningococcus''.<ref>{{Cite journal |vauthors=Weichselbaum A |year=1887 |title=Ueber die Aetiologie der akuten Meningitis cerebro-spinalis |journal=Fortschrift der Medizin |language=de |volume=5 |pages=573–83}}</ref> Mortality from meningitis was very high (over 90%) in early reports. In 1906, [[Biology:Antiserum|antiserum]] was produced in horses; this was developed further by the American scientist Simon Flexner and markedly decreased mortality from meningococcal disease.<ref>{{Cite journal |vauthors=Flexner S |date=May 1913 |title=The results of the serum treatment in thirteen hundred cases of epidemic meningitis |journal=The Journal of Experimental Medicine |volume=17 |issue=5 |pages=553–76 |doi=10.1084/jem.17.5.553 |pmc=2125091 |pmid=19867668 }}</ref><ref name="Swartz">{{Cite journal |vauthors=Swartz MN |date=October 2004 |title=Bacterial meningitis – a view of the past 90 years |journal=The New England Journal of Medicine |volume=351 |issue=18 |pages=1826–28 |doi=10.1056/NEJMp048246 |pmid=15509815}}</ref> In 1944, [[Chemistry:Penicillin|penicillin]] was first reported to be effective in meningitis.<ref>{{Cite journal |vauthors=Rosenberg DH, Arling PA |year=1944 |title=Penicillin in the treatment of meningitis |journal=Journal of the American Medical Association |volume=125 |issue=15 |pages=1011–17 |doi=10.1001/jama.1944.02850330009002}} reproduced in {{cite journal | vauthors = Rosenberg DH, Arling PA | title = Landmark article Aug 12, 1944: Penicillin in the treatment of meningitis. By D.H. Rosenberg and P.A.Arling | journal = JAMA | volume = 251 | issue = 14 | pages = 1870–76 | date = April 1984 | pmid = 6366279 | doi = 10.1001/jama.251.14.1870 }}</ref> The introduction in the late 20th century of ''[[Biology:Haemophilus|Haemophilus]]'' vaccines led to a marked fall in cases of meningitis associated with this pathogen,<ref name=Peltola/> and in 2002, evidence emerged that treatment with steroids could improve the prognosis of bacterial meningitis.<ref name="CochDex2013" /><ref name=deGans2002/><ref name=Swartz

== References ==
{{Reflist}}

== External links ==
{{Medical condition classification and resources
 | DiseasesDB     = 22543
 | ICD10          = {{ICD10|G|00||g|00}}–{{ICD10|G|03||g|00}}
 | ICD9           = {{ICD9|320}}–{{ICD9|322}}
 | MedlinePlus    = 000680
 | eMedicineSubj  = med
 | eMedicineTopic = 2613
 | eMedicine_mult = {{eMedicine2|emerg|309}} {{eMedicine2|emerg|390}}
 | MeshID         = D008581
}}
* {{curlie|Health/Conditions_and_Diseases/Neurological_Disorders/Meningitis}}
* [https://www.cdc.gov/meningitis/ Meningitis] U.S. Centers for Disease Control and Prevention (CDC)



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{{Sourceattribution|Meningitis}}