Meningitis is a bacterial infection of the membranes covering the brain and spinal cord (meninges).
The most common causes of meningitis are viral infections that usually get better without treatment. However, bacterial meningitis infections are extremely serious, and may result in death or brain damage, even if treated.
Meningitis may also be caused by:
Acute bacterial meningitis is a medical emergency, and requires immediate treatment in a hospital.
Viral meningitis is milder and occurs more often than bacterial meningitis. It usually develops in the late summer and early fall, and often affects children and adults under age 30. Most infections occur in children under age 5. Most viral meningitis is due to enteroviruses, which are viruses that also can cause intestinal illness.
Many other types of viruses can cause meningitis. For example, viral meningitis can be caused by herpes viruses, the same virus that can cause cold sores and genital herpes (although people with cold sores or genital herpes are not at a greater risk of developing herpes meningitis).
Recently, West Nile virus, spread by mosquito bites, has become a cause of viral meningitis in most of the United States.
Symptoms usually come on quickly, and may include:
Other symptoms that can occur with this disease:
Meningitis is an important cause of fever in children and newborns.
People cannot tell if they have bacterial or viral meningitis by how they feel, so they should seek prompt medical attention.
Physical examination will usually show:
For any patient who is suspected of having meningitis, it is important to perform a lumbar puncture ("spinal tap"), in which spinal fluid (known as cerebrospinal fluid, or CSF) is collected for testing.
Tests that may be done include:
Doctors prescribe antibiotics for bacterial meningitis. The type will vary depending on the bacteria causing the infection. Antibiotics are not effective in viral meningitis.
Other medications and intravenous fluids will be used to treat symptoms such as brain swelling, shock, and seizures. Some people may need to stay in the hospital, depending on the severity of the illness and the treatment needed.
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 lasting complications.
If you think that you or your child has symptoms of meningitis, get emergency medical help immediately. Early treatment is key to a good outcome.
The meningococcal vaccination is recommended for:
Some communities conduct vaccination campaigns after an outbreak of meningococcal meningitis.
Swartz MN. Meningitis: bacterial, viral, and other. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 437.