Meningitis: Causes

What causes meningitis?

The most common cause of meningitis is a virus, specifically enteroviruses, which are very common viruses that spread by hand-to-mouth contact, coughing, and contact with fecal matter of an infected person (such as changing the diaper of a baby infected with the virus). In most cases, enteroviruses cause a cold-like illness, but in some individuals the virus spreads to the membranes (meninges) that cover the brain and spinal cord and causes meningitis.

The second most common cause of meningitis is a bacterial infection, most frequently Neisseria meningitidis and Streptococcus pneumoniae. These bacteria are spread from person to person through coughing, sneezing and kissing. However, the bacteria are not spread as easily as other pathogens, such as the viruses that cause the common cold and influenza.

Once in the body, the bacteria can spread from the respiratory tract to the bloodstream where they are carried to the nervous system. In the nervous system they multiply and cause infection and inflammation of the meninges and cerebrospinal fluid (CSF).

Meningitis can also be caused by fungi and reactions to certain drugs and vaccines.

The different types of meningitis are named according to the cause, the length of time for the disease to develop, and the duration. Types of meningitis include:

• Acute bacterial meningitis is caused by bacteria, often Neisseria meningitidis.

• Aseptic meningitis is often caused by a viral infection, but can also be caused by a bacterial infection, certain drugs, reaction to a vaccine, or certain conditions, such as tuberculosis, brain surgery, head injury, Lyme disease, and syphilis.

• Chronic meningitis can be the result of side effects of certain drugs, such as chemotherapy, or can be caused by a viral, fungal, or bacterial infection.

• Viral meningitis is caused by a virus such as echovirus, coxsackie virus, or other type of enterovirus.

What are the risk factors for catching meningitis?

Meningitis can occur in any age group or population. A number of factors increase the risk of catching meningitis, although not all people with risk factors will catch meningitis. Risk factors for catching meningitis include:

• Crowded conditions, such living or working in military barracks, prisons, refugee camps, day care centers, or college dormitories

• Exposure to a person with meningitis

• Poor hygiene, such as not washing your hands frequently and thoroughly, or sharing unwashed drinking glasses, water bottles, dishware, or personal items, such as lip balm and toothbrushes

Reducing your risk of meningitis

You can lower your risk of catching or spreading meningitis by:

• Avoiding contact with a person who has meningitis

• Avoiding touching the eyes, nose and mouth, which can transmit meningitis bacteria from the hands into the body

• Covering the mouth and nose with the elbow (not the hand) or a tissue when sneezing or coughing

• Getting a bacterial meningitis vaccination as recommended by your health care provider

• Not sharing unwashed drinking glasses, water bottles, dishware, or personal items, such as lip balm and toothbrushes

• Using appropriate antibacterial cleaners to clean hands and surfaces

• Washing hands with soap and water for at least 15 seconds several times throughout the day and after contact with a person who has meningitis