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Acute bacterial meningitis is an infection of the meninges (the system of membranes which envelops the brain and spinal cord) that often causes hearing loss. Bacterial meningitis is fatal in 5% to 40% of children and 20% to 50% of adults despite treatment with adequate antibiotics. It is caused by bacteria that usually spread from an ear or respiratory infection and is treated with antibiotics. Co... more

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A.D.A.M. Medical Encyclopedia [Internet]. Atlanta (GA): A.D.A.M.; 2013.

A.D.A.M. Medical Encyclopedia.

Meningitis

Last reviewed: October 6, 2012.

Meningitis is a bacterial infection of the membranes covering the brain and spinal cord (meninges).

Causes, incidence, and risk factors

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:

  • Chemical irritation
  • Drug allergies
  • Fungi
  • Tumors

Most viral meningitis is due to enteroviruses, which are viruses that also can cause intestinal illness.

Many other types of viruses can cause meningitis. 

  • Viral meningitis can be caused by herpes viruses, the same virus that can cause cold sores and genital herpes . However, people with cold sores or genital herpes are not at a greater risk of developing herpes meningitis.
  • Viruses that cause mumps and HIV can cause aseptic meningitis.
  • Recently, West Nile virus, spread by mosquito bites, has become a cause of viral meningitis in most of the United States.

Symptoms

Viral meningitis occurs more often than bacterial meningitis, and is milder. It usually occurs in the late summer and early fall. It most often affects children and adults under age 30. 

Bacteria meningitis is an emergency. You will need immediate treatment in a hospital. 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.

You cannot tell if you have bacterial or viral meningitis by how they feel. Your health care provider must do this. Seek prompt attention if you have symptoms of meningitis. 

Signs and tests

The doctor or nurse will examine you. This may show:

  • Fast heart rate
  • Mental status changes
  • Stiff neck

If the health care provider thinks you have meningitis, a lumbar puncture (spinal tap) should be done to remove a sample of spinal fluid (cerebrospinal fluid, or CSF) for testing.

Other tests that may be done include:

Treatment

Antibiotics are used to treat bacterial meningitis. The specific type depends on which bacteria is causing the infection. Antibiotics do not treat viral meningitis.

Antiviral medicine may be given to those with herpes meningitis.

Other treatments will include:

  • Fluids through a vein (IV)
  • Medicines to treat symptoms such as brain swelling, shock, and seizures

Expectations (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 lasting complications.

Complications

Calling your health care provider

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.

Prevention

Certain vaccines can help prevent some types of meningitis.

  • Haemophilus vaccine (HiB vaccine) in children helps prevent one type of bacterial meningitis.
  • The pneumococcal conjugate vaccine is now a routine childhood immunization. It is very effective at preventing pneumococcal meningitis.

Household members and others in close contact with people who have meningococcal meningitis should receive antibiotics to prevent becoming infected.

The meningococcal vaccination is recommended for:

  • Adolescents ages 11 - 12 and adolescents entering high school (about age 15) who have not already received the vaccination. A booster shot is given between age 16-18.
  • All college freshmen who have not been vaccinated and are living in dorms.
  • Children age 2 and older who do not have their spleen or who have other problems with their immune system.
  • Those traveling to countries where diseases caused by meningococcus are very common (ask your doctor).

Some communities hold vaccination campaigns after an outbreak of meningococcal meningitis.

References

  1. Swartz MN. Meningitis: bacterial, viral, and other. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 360.
  2. Tunkel AR, Van de Beek D, Scheld WM. Acute meningitis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009: chap 84. 

Review Date: 10/6/2012.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.

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The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsementscof those other sites. © 1997–2011 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Copyright © 2013, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsementscof those other sites. © 1997–2011 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Copyright © 2013, A.D.A.M., Inc.

What works?

  • Corticosteroids for managing tuberculous meningitisCorticosteroids for managing tuberculous meningitis
    Tuberculous meningitis is a serious form of tuberculosis affecting the meninges covering the brain and spinal cord. The clinical outcome is poor even when treated with conventional antituberculous drugs. Corticosteroids are commonly used in addition to antituberculous drugs for treating the condition. They help reduce swelling and congestion of the meninges, and thus decrease pressure inside the brain and the attendant risk of death or disabling residual neurological deficit among survivors. This review identified seven trials involving 1140 people that evaluated either dexamethasone or prednisolone given in addition to antituberculous drugs; only one trial was of high quality. Overall, the trials showed that corticosteroids help reduce the risk of death or a risk of death or disabling residual neurological deficit. Only one trial evaluated the effects of corticosteroids in HIV‐positive people, but the effects were unclear. Given the results of the review, all HIV‐negative people with tuberculous meningitis should receive corticosteroids, but more trials are needed in HIV‐positive people.
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Figures

  • Brudzinski's sign of meningitis.
    Kernig's sign of meningitis.
    Lumbar puncture (spinal tap).
    Meninges of the brain.
    Meninges of the spine.
    Haemophilus influenza organism.

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