Meningitis is an infection that causes inflammation of the membranes covering the brain and spinal cord. Non-bacterial meningitis is often referred to as "aseptic meningitis." Bacterial meningitis may be referred to as "purulent meningitis."
Causes, incidence, and risk factors
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, drug allergies, and tumors.
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, Neisseria 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 intestinal illness.
However, many other types of viruses can also cause meningitis. For example, viral meningitis may occur as a complication in people with genital herpes.
Meningitis - H. influenzae (2 images)(Doctor-Reviewed information)
Haemophilus influenzae meningitis is an infection of the membranes covering the brain and spinal cord (meninges) caused by H. influenzae bacteria. Reviewer: Hilary M. Babcock, M.D., Medical Director of Occupational Infection Control, Barnes-Jewish and St. Louis Children's Hospitals; Instructor of Medicine, Infectious Disease Division, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.Date: 09/06/2006
Meningitis - cryptococcal (1 image)(Doctor-Reviewed information)
Cryptococcal meningitis is an infection of the meninges (the membranes covering the brain and spinal cord), caused by the fungus Cryptococcus neoformans. Reviewer: Hilary M. Babcock, M.D., Medical Director of Occupational Infection Control, Barnes-Jewish and St. Louis Children's Hospitals; Instructor of Medicine, Infectious Disease Division, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.Date: 09/06/2006
Meningitis - meningococcal (1 image)(Doctor-Reviewed information)
Meningococcal meningitis is an infection that causes inflammation of the membranes covering the brain and spinal cord. Reviewer: Hilary M. Babcock, M.D., Medical Director of Occupational Infection Control, Barnes-Jewish and St. Louis Children's Hospitals; Instructor of Medicine, Infectious Disease Division, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.Date: 08/15/2006
Meningitis - pneumococcal (2 images)(Doctor-Reviewed information)
Pneumococcal meningitis is an inflammation or infection of the membranes covering the brain and spinal cord caused by Streptococcus pneumoniae (also called pneumococcus. Reviewer: Hilary M. Babcock, M.D., Medical Director of Occupational Infection Control, Barnes-Jewish and St. Louis Children's Hospitals; Instructor of Medicine, Infectious Disease Division, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.Date: 08/15/2006
Meningitis - staphylococcal (1 image)(Doctor-Reviewed information)
Staphylococcal meningitis is an infection of the membranes covering the brain and spinal cord (meninges), caused by Staphylococcus bacteria. Reviewer: Hilary M. Babcock, M.D., Medical Director of Occupational Infection Control, Barnes-Jewish and St. Louis Children's Hospitals; Instructor of Medicine, Infectious Disease Division, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.Date: 09/06/2006
Aseptic meningitis (1 image)(Doctor-Reviewed information)
Aseptic meningitis is an illness characterized by headache, fever, and inflammation of the lining of the brain (meninges. Although it looks like bacterial meningitis, bacteria do not grow in cultures of the cerebrospinal fluid (fluid around the brain and spinal cord. Reviewer: Hilary M. Babcock, M.D., Medical Director of Occupational Infection Control, Barnes-Jewish and St. Louis Children's Hospitals; Instructor of Medicine, Infectious Disease Division, Washington University School of Medicine, St. Louis, MO. Review provided by VeriMed Healthcare Network.Date: 09/06/2006
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