Causes and Risks:

The most common causes of meningitis are viral infections that usually resolve without treatment. However, bacterial infections of the meninges are extremely serious illnesses, and may result in death or brain damage even if treated. Meningitis is also caused by fungi, chemical irritation or drug allergies, and tumors.

Types include:

• meningitis - cryptococcal
• syphilitic aseptic meningitis
• meningitis - H. influenza
• meningitis - meningococcal
• meningitis - pneumococcal
• meningitis - staphylococcal
• meningitis - tuberculous
• aseptic meningitis
• meningitis gram negative
• carcinomatous meningitis (meningitis due to cancer)

Acute bacterial meningitis is a true medical emergency, and requires immediate hospital-based treatment. Bacterial strains that cause meningitis include Streptococcus pneumoniae, Haemophilus influenzae, Neiserria meningitidis (meningococcus), Listeria monocytogenes, and many other types of bacteria. In the U.S. about 17,500 cases of bacterial meningitis occur each year.

Viral meningitis is milder and occurs more often than bacterial meningitis. It usually develops in the late summer and early fall, often affects children and adults under 30. Seventy percent of the infections occur in children under the age of 5. Most viral meningitis is associated with enteroviruses, which are viruses that commonly cause stomach flu. However, many other types of viruses can also cause meningitis; for example, viral meningitis may occur as a complication in people with genital herpes.

Prevention:

• Haemophilus vaccine (HiB vaccine) in children will help prevent one type of meningitis.
• It is highly recommended that household contacts and individuals with close contact with individuals with meningococcal meningitis (see meningitis - meningococcal ) receive preventative antibiotics to avoid becoming infected themselves.
• Some communities conduct vaccination campaigns following an outbreak of meningococcal meningitis. Military recruits are routinely vaccinated against this form of meningitis because of its high rate of occurence. Some authorities believe that college students living in dormitories should also be vaccinated.

Symptoms:

• fever and chills
• headache, severe
• nausea and vomiting
• stiff neck ("meningismus")
• sensitivity to light (photophobia)
• mental status changes

• consciousness, decreased
• breathing, rapid
• agitation
• opisthotonos (severe neck stiffness, ultimately resulting in a characteristic arched posture-seen in infants or small children)
• "bulging fontanelles" may be seen in infants
• poor feeding or irritability in children

Meningitis is an important cause of fever in newborn children. For this reason, a lumbar puncture is often done on newborns who have a fever of uncertain origin.

Signs and Tests:

• Lumbar puncture with CSF glucose measurement and CSF cell count.
• Gram-stain and culture of CSF (cerebral spinal fluid).
• Chest X-ray to look for other sites of infection.
• Head CT scan looking for hydrocephalus, abscess or deep swelling.

Treatment: Antibiotics will be prescribed for bacterial meningitis; the type will vary depending on the infecting organism. Antibiotics are ineffective in viral meningitis. Treatment of secondary symptoms including brain swelling, shock, and convulsions will require other medications and intravenous fluids. Hospitalization may be required depending on the severity of the illness and the needed treatment.

Prognosis: Early diagnosis and treatment of bacterial meningitis is essential to prevent permanent neurological damage. Viral meningitis is usually not serious, and symptoms should disappear within 2 weeks with no residual complications.

Complications:

• hearing loss / deafness
• brain damage
• loss of vision
• hydrocephalus

If you feel that you or your child have symptoms suggestive of meningitis, you must seek emergency medical help immediately. Early treatment is key to a good outcome.