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What is meningitis?

Ilustration of the meninges
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Meningitis is a disease caused by an inflammation of the meninges, the membranes that surround the brain. The inflammation is usually caused by infection of the fluid surrounding the brain and spinal cord. There are three meninges, including the following:

  • Dura mater. This is the outside membrane that adheres to the inside of the skull.

  • Arachnoid. This is the middle membrane.

  • Pia mater. This is the innermost membrane, which adheres to the brain.

What causes meningitis?

There are two distinct types of meningitis, each with different causes:

Viral (caused by a virus)

  • Viral meningitis is more common than bacterial meningitis, although rarely life threatening. Viral meningitis can be caused by different viruses, and is spread between people by coughing or sneezing, or through poor hygiene. Other germs can be found in sewage polluted water. On rare occasions, certain insects, such as mosquitos and ticks, are thought to pass on these viruses. Insect bites would then be the way the virus is introduced into a patient, with the spread of the virus from the blood to the brain.

  • Viral meningitis can, in rare circumstances, be helped by special antiviral medications that specifically target certain viruses. Recovery is normally complete, but headaches, fatigue, and depression may persist.

Bacterial (caused by a bacterium)

  • Bacterial meningitis, although rare, may be fatal.

  • Bacteria may be spread through the exchange of respiratory and throat secretions, such as coughing and kissing.

  • Many species of bacteria can cause meningitis. Below are four types: 

    • Neisseria meningitidis (meningococcus). Meningococcus is a common cause of bacterial meningitis in children two to 18 years of age. It is spread by respiratory droplets and close contact. For unknown reasons, only a small fraction of carriers develop meningitis. Meningococcal meningitis occurs most often in the first year of life, but may also occur in closed populations, such as schools.

    • Streptococcus pneumoniae (pneumococcus). Pneumococcus is the most common and most serious form of bacterial meningitis. Those at high risk may include persons with weakened immune systems.

    • Haemophilus influenzae type b. The development of the Haemophilus influenzae type b vaccine has drastically decreased the number of cases in the U.S. Children who do not have access to the vaccine and those in day-care centers are at higher risk of acquiring Haemophilus meningitis.

    • Listeria monocytogenes. Listeria monocytogenes has become a more frequent cause of meningitis in neonates, pregnant women, persons over the age of 60, and in persons of all ages who are immunocompromised.

How does the infection reach the brain?

The infection can reach the brain via several different routes, including through the bloodstream from another infected part of the body, through the bones of the skull from infected sinuses or inner ears, or from a head injury, such as a fractured skull or penetrating wound. In particular, this occurs when the body's resistance is compromised by certain factors such as following surgery or an extended hospitalization, a weakened immune system, or as a result of chronic kidney failure.

What are the symptoms of meningitis?

The following are the most common symptoms of meningitis. However, each individual may experience symptoms differently. Symptoms may include:

  • Fever

  • Headache

  • Nausea and vomiting

  • Stiff neck

  • Photophobia (low tolerance to bright light)

  • Confusion

  • Joint aches or pains

  • Drowsiness

  • Seizures

Symptoms for children may also include:

  • Fever

  • High-pitched cry

  • Pale, blotchy skin color

  • Not wanting to eat

  • Vomiting

  • Fretful and fussy

  • Arching back

  • Difficult to wake

It is important to note that these symptoms may not occur all at once, nor in everyone who contracts meningitis. The symptoms of meningitis may resemble other conditions or medical problems. Always consult your health care provider for a diagnosis.

How is meningitis diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for meningitis may include the following:

  • Lumbar puncture (also called spinal tap). A special needle is placed into the lower back, into the spinal canal. This is the area around the spinal cord. The pressure in the spinal canal and brain can then be measured. A small amount of cerebral spinal fluid (CSF) can be removed and sent for testing to determine if there is an infection or other problems. CSF is the fluid that bathes the brain and spinal cord. 

  • Blood testing

  • Computed tomography scan (also called a CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays.

Treatment for meningitis

Specific treatment for meningitis will be determined by your health care provider based on:

  • Your age, overall health, and medical history

  • Extent of the disease

  • The organism that is causing the infection

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the disease

  • Your opinion or preference

Treatment may include:

  • Bacterial meningitis. Treatment for bacterial meningitis usually involves intravenous (IV) antibiotics. The earlier the treatment is initiated, the better the outcome.

    While steroid administration has been shown to be helpful in treating bacterial meningitis in infants and children, this treatment is used less frequently in adults. Dexamethasone, a type of steroid, may be given in more acute cases of bacterial meningitis, to decrease the inflammatory response caused by the bacteria.

  • Viral meningitis. Treatment for viral meningitis is usually supportive (aimed at relieving symptoms). With the exception of the herpes simplex virus, there are no specific medications to treat the organisms that cause viral meningitis. Sometimes antiviral medications are used to combat some other specific types of viruses, with variable benefit.

  • Fungal meningitis. An intravenous antifungal medication may be administered to treat fungal meningitis.

  • Tuberculous (TB) meningitis. A long course (one year) of medications is recommended for people who develop TB meningitis. The therapy usually involves treatment with several different medications for the first few months, followed by other medications.

What is supportive therapy for meningitis?

While a person is recovering from meningitis, other therapies may be initiated to improve healing and comfort, and provide relief from symptoms. These may include the following:

  • Bed rest in a dimly lit room

  • Medications to reduce fever and headache. Aspirin should be avoided.

In addition, supplemental oxygen or mechanical ventilation (respirator) may be required if you become very ill and have difficulty breathing.

Prevention of meningitis

Several vaccines are currently available to prevent some of the bacterial organisms that can cause meningitis. However, routine vaccination with these vaccines is recommended primarily for infants and children. Two doses at ages 11 through 18 are also recommended. 

In certain conditions, your health care provider may recommend one of the meningitis vaccines. These conditions may include, but are not limited to, the following:

  • Chronic lung conditions, such as emphysema or COPD

  • Heart disease

  • Diabetes

  • Chronic renal (kidney) failure

  • Travel to countries where meningitis is prevalent

  • Decreased immunity status

  • Certain blood disorders

If you have questions regarding prevention, consult your health care provider.