Types of meningitis
What is meningitis?
Meningitis is an inflammation of the fluid and membranes that cover the brain and spinal cord. Every year over 2 million people worldwide are affected by meningitis. Meningitis can be caused by:
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Bacteria
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Viruses
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Fungi
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Parasites
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Non-infectious means such as cancer or lupus.
How is it spread?
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The most serious form is bacterial meningitis. Many people carry meningitis bacteria in their nose and throat. These bacteria usually cause no harm and help to build up immunity against infection. Only on rare occasions do the bacteria cause disease.
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The bacteria spread from person to person through respiratory droplets for example, by coughing and close contact such as kissing.
Bacterial meningitis
Bacterial meningitis is a medical emergency that develops quickly and can lead to permanent disability or death in just a few hours.
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Bacterial meningitis accounts for around 300,000 deaths around the world each year. Most of these deaths occur within 24-48 hours after the onset of symptoms.
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It is fatal in up to 10 to 20% of cases.
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Septicaemia (blood poisoning) is a potentially life-threatening infection that occurs when the bacteria that cause meningitis get into the bloodstream. The infection may be seen alone or in addition to meningitis.
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Some types of bacterial meningitis can be prevented through vaccination.
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Most cases of bacterial meningitis are caused by Neisseria meningitidis (the meningococcus) , Streptococcus pneumoniae (the pneumococcus) and Haemophilus influenzae Type B (Hib).
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There are different types of all three bacteria called serogroups or serotypes.
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Meningococcus serogroups A, B, C, W and Y are responsible for over 95% of meningococcal meningitis and septicaemia cases.
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Other bacteria that can cause meningitis include Escherichia coli and Group B Streptococcus (common causes of neonatal meningitis) and Mycobacterium tuberculosis (TB).
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Viral meningitis
Viral meningitis is the most common kind of meningitis and is usually less severe than bacterial meningitis. Most people recover without any permanent damage, although full recovery can take many weeks or months.
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Many viruses can cause meningitis, and these usually spread through respiratory droplets (kissing, coughing, sneezing) or by faecal contamination.
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The most common group, enteroviruses, live in the respiratory and intestinal tracts and can cause colds and sore throats usually with fever, headache, and muscles aches. From time to time, enteroviruses spread to the meninges and cause meningitis.
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The mumps virus can also cause meningitis, but due to the combined measles-mumps-rubella vaccine (MMR), this form of meningitis is now rare in countries with high MMR immunisation rates.
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Vaccines are not available to protect against many types of viral meningitis, but good hygiene can help prevent spread.
Fungal meningitis
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Fungal meningitis can be severe but occurs infrequently.
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Fungal meningitis is not contagious and spreads by inhaling fungal spores from the environment.
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Most cases occur in people with impaired immune systems, including people with AIDS.
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Vaccines are not available to protect against fungal meningitis.
Other Types of Meningitis
It is also possible to contract meningitis from parasites or through non-infectious means including:
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Cancers
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Lupus
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Certain drugs
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Head injuries
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Brain surgery
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Or an existing condition of the skull or spine.
References:
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Murray CJL, Vos T, Naghavi, et al. Disability-adjusted life years (DALYS) for 291 diseases and injuries in 21 regions, 1990-2010: a systemic analysis for the Global Burden of Disease Study. Lancet 2012;380:2197-223.
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McIntyre PB, O’Brien KL, Greenwood B, van de Beck D. Effect of vaccines on bacterial meningitis worldwide. Lancet 2012; 380: 1703–11