Medical Specialties: Emergency medicine, Family practice, Pediatrics

Clinical Definition

Meningitis is an infection of the meninges, the protective membranes that surround the brain and spinal cord. Meningitis may develop in response to a number of causes, usually bacteria or a virus, but it can also be caused by certain physical injuries, cancers or drugs.

In Our Own Words

Although relatively rare, meningitis is an extremely serious disease that can set in quickly and be life-threatening. The most common form of meningitis is acute bacterial meningitis, which is responsible for about 80 percent of cases.


Meningitis-causing bacteria are usually found in the environment, but can also exist in the human body (e.g., in the nose) without causing harm. Meningitis can also strike after a head injury or if a patient suffers a weak immune system. Unfortunately, not all causes of meningitis are known.


Children are most susceptible to this infection. However, adults can also get meningitis, especially those who have had their spleen removed or those with a weakened immune system, sickle cell disease, head injury or widespread blood infection. Depending on the cause of meningitis and how long it takes to get medical care, the response to therapy and long-term outcomes can vary. For caregivers, it is important to seek immediate help if you suspect meningitis. Symptoms may set in within 24 hours, and seizures and stroke may occur.

Relevant Conditions
  • Cancer
  • Parasites
Common Types
  • Bacterial meningitis
  • Viral meningitis
Side Effects
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  • Cleveland Clinic. “Meningitis.” Accessed July 2013.
  • Centers for Disease Control and Prevention. “Meningitis.” Updated March 2012. Accessed July 2013.
  • Centers for Disease Control and Prevention. “Multistate Fungal Meningitis Outbreak - Current Case Count.” Updated August 2013. Accessed August 2013.
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