What is meningitis: What causes meningitis?

What is meningitis?  Meningitis is a life threatening inflammation of the meninges  that causes  sensitivity to light and sound, altered thinking, confusion, headache and neck stiffness.  The most common symptom, however, is a severe headache.  Meningitis can be life threatening because of the meninges proximity to the brain and spinal cord.  Inflammation to the meninges is rarely caused by medications, and is most commonly caused by bacterial and viral infections. 

Understanding more about what is meningitis will help you talk with your doctor and live a better life.

Even with treatment, bacterial meningitis is typically fatal.  With the presence of a rash, meningococcal bacteria is likely the cause.  Early signs of meningitis include: falling blood pressure, abnormal body temperature and rapid breathing.  In infants, many of these symptoms may go unnoticed.  A child suffering from meningitis will seem abnormally irritable and may develop altered skin coloration.  Further, a soft spot on the effected child’s head may appear, sometimes before other symptoms are present. Meningitis can lead to long term cognitive defects, epilepsy and hydrocephalus, a life-threatening condition characterized by an abnormal accumulation of cerebrospinal fluid (CSF) in the brain.  Some forms of meningitis, specifically those caused by bacterial infection, can be prevented with immunization.

What causes meningitis?
Viruses are the most common cause of infection leading to meningitis.  Microorganisms, bacteria, fungi, and parasites are all known causes of meningitis.  Both viral and bacterial meningitis are contagious and can be spread by saliva and mucus.  Meningitis cannot be spread through the air.  Epidemics of meningitis occur in newborn populations, usually from the bacteria Listeria monocytogenes.  In countries that do not offer immunizations, Neisseria meningitidis,  Streptococcus pneumoniae, Haemophilus influenzae type B are the leading cause of meningitis in children.  N. meningitidis and S. pneumonia are the most common bacteria and cause 80% of cases.

Aseptic meningitis, referring to non-bacteria caused cases, can be caused by viruses or infection to areas surrounding the meninges.  Those suffering from immune-deficiency disorders such as AIDS, or those taking immune-suppressant drugs have an increased risk of fungal-meningitis or amoebic meningitis, contracted by the inhalation of amoebas in hot, stagnant freshwater.  Though rare, people with healthy immune systems can contract amoebic meningitis, specifically if there has been trauma to the cranium or nasal cavity.  Though rare, certain types of cancer and medication can affect the meninges, causing meningitis.

What are the treatments for meningitis?
To diagnose meningitis, blood samples, blood cultures and a lumbar puncture (spinal tap) are used.  If detected, CT or MRI scans are used to diagnose the particular type of meningitis and its possible effects.  A lumbar puncture is used to test the level of cerebral spinal fluid (CSF), as a common symptom of meningitis is an increase in this fluid around the brain and spinal cord.  A gram stain of this fluid is used to identify which virus or bacteria is causing the disease.  Preventative measures include good hygiene, avoiding fecal matter and avoidance of a person suffering from meningitis.

Once meningitis has been determined, it is important to start treatment immediately. While various types of meningitis require different treatments, a gram stain will confirm if the cause is bacterial or not, thereby directing treatment.  Bacterial meningitis is treated primarily with antibiotics.  For -bacterial and non-bacterial meningitis, corticosteroids are used to reduce inflammation, thereby greatly reducing the risk of mortality and permanent damage. Fungal meningitis is treated with long term antifungal medication such as amphotericin B and flucytosine.  Viral meningitis tends to be less severe, though harder to treat; thereby the treatment of viral meningitis typically calls for supportive therapy and the use of antiviral medication.

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