Meningitis (meh-nin-JY-tis) is an inflammation of the membranes that surround the brain and the spinal cord (the meninges, meh-NIN-jeez). Meningitis is most often caused by infection with a virus or a bacterium.
Meningitis is an inflammation of the meninges, the membranes that enclose and protect the brain and the spinal cord. It is usually caused by infection, most often from viruses or bacteria. Meningitis caused by bacteria is known as septic meningitis. Meningitis caused by other organisms, including viruses, fungi, and parasites, is called aseptic (a-SEP-tik) meningitis. Viral meningitis is the most common and mildest form of the disease, and most people fully recover from it without complications. Bacterial meningitis, if not diagnosed early, can cause serious and sometimes fatal complications.
Enteroviruses, a group of viruses that includes several strains of coxsackieviruses (kok-SAH-kee-VY-ruh-sez) and echoviruses * , cause about 90 percent of cases of aseptic meningitis. Two types of bacteria that are most likely to cause septic meningitis are Streptococcus pneumoniae (strep-tuh-KAH-kus nu-MO-nye) and Neisseria meningitidis (nye-SEER-e-uh mehnin-JY-tih-dis), also called meningococcus (meh-NIN-guh-kah-kus). Before the introduction of a vaccine * * as well, such as some species of parasites and fungi and the bacteria that cause Lyme disease * , tuberculosis * , and syphilis * . Meningitis from these organisms is usually a complication of widespread infection throughout the body and is more likely to be seen in people who have immune problems or such other diseases as AIDS * or cancer. Sometimes chemical irritations, severe drug allergies, or tumors can lead to inflammation in the central nervous system * , resulting in meningitis.
Bacterial meningitis, especially meningococcal meningitis, sometimes occurs in epidemics * in underdeveloped parts of the world, but epidemics are less common in the United States. Because of vaccinations * (vak-sih-NAY-shunz) against some of the bacteria that can cause meningitis, the overall number of cases of septic meningitis steadily declined after 1990. Vaccinated infants and young children are much less likely to contract bacterial meningitis. But after the late 1990s, there was an increase in the number of cases of meningococcus infection seen in young adults, particularly in college students who live in dormitories. As of 2016, there were about 4,100 cases of bacterial meningitis in the United States each year, and about 500 deaths.
Bacteria that can cause meningitis are sometimes found in the throats and noses of healthy people. They are spread through direct contact with respiratory secretions (drops of fluid from the mouth, nose, or lungs), which means they can be passed to someone who kisses an infected person or to someone who touches the secretions from someone who is sneezing or coughing and then touches his or her own nose or mouth. Meningococcus can spread in this way through households, day care centers, and college dormitories.
Enteroviruses commonly are passed from person to person through contact with respiratory secretions; by breathing in droplets from someone who is coughing or sneezing; and from contact with an infected person's feces (FEE-seez, or bowel movements).
Symptoms of meningitis often include fever, headache, stiff neck and back, photophobia (painful sensitivity of the eyes to light), abnormal sleepiness, and confusion. The patient may also vomit. Infants’ symptoms are not as specific as those in older children and adults but usually include irritability, lethargy, poor feeding, crying when moved, and vomiting. Infants may not have neck or back stiffness while ill with meningitis. Meningococcus can cause a reddish-purple rash (from bleeding under the skin) that rapidly spreads over the body. Seizures * can occur in anyone with meningitis, regardless of age.
A doctor first asks questions about the illness, does a physical examination, and then performs some tests. The brain is sometimes viewed with a computed tomography * (CT) scan to rule out other reasons for severe headache and illness, such as an abscess * , tumor, or other problems within the brain. A lumbar puncture (also called a spinal tap * ) is usually done to take a sample of the cerebrospinal (seh-ree-bro-SPY-nuhl) fluid (CSF), the fluid that surrounds the brain and spinal cord. The CSF is then examined under a microscope in order to identify bacteria or other infectious agents and to calculate increased numbers of white blood cells indicating inflammation.
Antibiotics are not used to treat viral meningitis because it is caused by a virus, not bacteria. Once a case of meningitis is known to be viral, rest and pain medication for body aches and headache can help the person feel better until the infection resolves on its own.
Bacterial meningitis requires prompt medical treatment, usually in the hospital. Antibiotics are given for at least two weeks to fight the invading organism. Treatment of complications may require intensive care and other medications.
Meningitis that results from other types of infection or other causes is treated with medications, such as antifungal * or antiparasitic drugs, and may require hospitalization, especially during the early stages of medical care.
Most cases of viral meningitis last one to two weeks, and most people recover completely. Symptoms from bacterial meningitis can last weeks, and people may have severe complications from the disease, especially if it is not diagnosed and treated promptly.
Complications from viral meningitis are not as common as those from bacterial meningitis, but they can include inflammation and swelling of the brain. Sometimes, permanent learning disability and other brain damage can result.
Complications from bacterial meningitis can occur rapidly and be severe, even with quick diagnosis and treatment of the disease. Complications include sepsis * , brain swelling, seizures, shock * , organ failure (such as failure of the kidneys * ), and death. Up to 17 percent of cases of meningitis caused by the meningococcus are fatal. Long-term effects are seen in as many as 20 percent of those who survive bacterial meningitis and can include hearing loss, seizure disorder, learning disabilities, and other problems resulting from brain injury. Meningitis caused by the bacteria that cause tuberculosis is particularly likely to damage the nervous system.
Vaccinations against H. influenzae type b and S. pneumoniae are given routinely to children in the United States before the age of two years. A vaccine against meningococcus is available in the United States. On October 29, 2014, the Food and Drug Administration (FDA) licensed the first serogroup B meningococcal vaccine (Trumenb®). The FDA approved this vaccine for use in people age 10 through 25 years as a three-dose series. On January 23, 2015, the FDA licensed a second serogroup B meningococcal vaccine (Bexsero®). The FDA approved this vaccine for use in people age 10 through 25 years as a two-dose series. Many school districts and colleges expect students to receive the meningococcal vaccination before attending classes or moving into dormitories, as recommended by the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics. It also is recommended for people traveling outside the United States, people living in certain institutional settings, the elderly, and people with some chronic * medical conditions.
During outbreaks of bacterial meningitis, especially those caused by meningococcus, in schools, dormitories, or day care centers, people may be given prophylactic * antibiotics to keep the disease from occurring in those who were in close contact with the infected person.
It is difficult to keep viruses like enteroviruses from spreading from person to person. Risk of viral infection can be decreased by washing hands regularly, especially after using the toilet; and avoiding close contact with anyone who is ill, including not sharing food, eating or serving utensils, razors, or other personal items.
See also AIDS and HIV Infection • Bacterial Infections • Coxsackievirus and Other Enteroviruses • Fungal Infections • Lyme Disease • Syphilis • Tuberculosis • Vaccines and Immunization • Viral Infections
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* echoviruses are a group of viruses found in the intestinal tract. The word echo in the name is an acronym for enteric cytopathic human orphan viruses. When these viruses were named, they were not associated with any disease, hence the use of the word orphan. However, these viruses were later associated with various diseases, including meningitis and encephalitis.
* vaccine (vak-SEEN) is a preparation of killed or weakened germs, or a part of a germ or product it produces, given to prevent or lessen the severity of disease if a person is exposed to the germ itself. Use of vaccines for this purpose is called immunization.
* pathogens (PAH-tho-jens) are microorganisms that can cause disease in another living organism.
* Lyme disease (LIME) is a bacterial infection transmitted to humans by the bite of an infected tick. It begins with a distinctive rash and/or flulike symptoms; in some cases, it can progress to a more serious disease with complications affecting other body organs.
* tuberculosis (too-ber-kyoo-LO-sis) is a bacterial infection that primarily attacks the lungs but can spread to other parts of the body.
* syphilis (SIH-fih-lis) is a sexually transmitted disease that, if untreated, can lead to serious life-long problems throughout the body, including blindness and paralysis.
* AIDS (or Acquired Immunodeficiency [ih-myoo-no-dih-FIH-shensee] Syndrome) is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).
* central nervous system (SEN-trul NER-vus SIS-tem) is the part of the nervous system that includes the brain and spinal cord.
* epidemics (eh-pih-DEH-miks) are outbreaks of diseases, especially infectious diseases, in which the number of cases suddenly becomes far greater than usual. Usually epidemics are outbreaks of diseases in specific regions, whereas widespread epidemics are called pandemics.
* vaccination (vak-sih-NAY-shun) is giving, usually by an injection, a preparation of killed or weakened germs, or a part of a germ or product it produces, to prevent or lessen the severity of the disease caused by that germ. Also called immunization.
* seizures (SEE-zhurs), also called convulsions, are sudden bursts of disorganized electrical activity that interrupt the normal functioning of the brain, often leading to uncontrolled movements in the body and sometimes a temporary change in consciousness.
* computed tomography (kom-PYOO-ted toe-MAH-gruhfee), or CT, also called computed axial tomography (CAT), is an imaging technique in which a machine takes many x-rays of the body to create a threedimensional picture.
* abscess (AB-ses) is a localized or walled-off accumulation of pus caused by infection that can occur anywhere in the body.
* spinal tap, also called a lumbar puncture, is a medical procedure in which a needle is used to withdraw a sample of the fluid surrounding the spinal cord and brain. The fluid is then tested, usually to detect signs of infection.
* sepsis is a potentially serious spreading of infection, usually bacterial, through the bloodstream and body.
* shock is a serious condition in which blood pressure is very low and not enough blood flows to the body's organs and tissues. Untreated, shock may result in death.
* kidneys are the pair of organs that filter blood and remove waste products and excess water from the body in the form of urine.
* chronic (KRAH-nik) means lasting a long time or recurring frequently.
* prophylactic (pro-fih-LAK-tik) refers to something that is used to prevent an illness or other condition, such as an infection or pregnancy.
* antifungal drugs (an-ty-FUNG-al) are medications that kill fungi.