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Meningitis means an inflammation of the lining of the brain and spinal cord (called the meninges). It can be caused by infectious or non-infectious agents. The degree of morbidity and mortality associated with meningitis varies with the causative agent, the age of the person, and any preexisting medical conditions.

Bacteria, virus, parasites, and fungi are infectious causes of meningitis; some non-infectious agents include drugs, radiographic dyes, and tumors.

The symptoms of infectious meningitis include fever, headache, stiff neck (called nuchal rigidity), nausea, vomiting, eye discomfort in bright light (called photophobia), irritability, and change in mental status. Infants may have poor feeding.

Bacterial meningitis
The most common bacterial causes are Group B Streptococcus (GBS), Streptococcus pneumoniae (also called pneumococcus), Haemophilus influenzae, Neisseria meningitides (also called meningococcus), and Listeria monocytogenes.

Bacterial meningitis is NOT spread through casual contact or the airborne route; however, some bacteria can be spread by close contact with respiratory droplets (e.g., in daycare centers). Based on age or risk factors, certain persons should receive vaccinations for GBS, Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitides. Antibiotic prophylaxis is only indicated for close contacts of persons with Haemophilus influenzae or meningococcal meningitis. Healthcare workers do not have a high risk of catching meningococcal meningitis and prophylaxis is indicated only for persons directly exposed to the patient’s oral secretions (e.g., mouth-to-mouth resuscitation, endotracheal intubation, or endotracheal tube management).

Viral meningitis
Viral meningitis, often referred to as aseptic meningitis, is generally a self-limiting illness. It can affect anyone, but the very young and persons with weakened immune systems are at the highest risk. The following viruses can cause meningitis:

  • Enteroviruses— the most common cause
  • Mumps and measles
  • Herpes virus, including Epstein-Barr virus, herpes simplex viruses, and varicella-zoster virus
  • Influenza
  • Viruses spread through mosquitoes and other insects (arboviruses)
  • Lymphocytic choriomeningitis virus

Enteroviral infections can be spread person to person via fecal contamination. Enteroviruses and viruses such as mumps and varicella may also be spread through direct or indirect contact with saliva, sputum, or mucus of an infected person. Antibiotics are not effective for viral meningitis although antiviral treatment is available for herpes viruses. Thus, post exposure prophylaxis is not indicated.

 

What you can do:
It can be difficult to distinguish the cause of meningitis based on symptoms, although the presentation of viral meningitis tends to be less severe than bacterial cases. Laboratory tests, specifically blood cultures and cerebrospinal fluid (CSF) analysis, will assist with determining the treatment, need for precautions, and potential prophylaxis of contacts.

A comparison of CSF results helps distinguish between bacterial and viral causes:

  Glucose Protein WBC Type of cells
Bacterial Normal to decreased Increased > 1000/mm3 Neutrophils
Viral Normal Normal to increased < 100/ mm3 Lymphocytes

If the patient has not had any antibiotics, the gram stain in bacterial meningitis will be positive, whereas it will be negative for viral meningitis. Bacterial antigen tests and cultures will further determine the specific organisms.

Healthcare personnel should use standard precautions when caring for meningitis patients. Transmission based precautions should be followed for disease-specific illness. For example:

  • Meningococcal – droplet for 24 hours after effective treatment
  • Haemophilus influenza – droplet for 24 hours after effective treatment
  • Enterovirus – Contact precautions for diapered or incontinent children for duration of illness

Prevention is key. Be sure to encourage vaccination for those most at risk for bacterial meningitis.

 

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