What is meningitis?
Meningitis is an infection of the meninges, the membranes that surround the brain and spinal cord. Infections and other disorders affecting the brain and spinal cord can activate the immune system, which leads to inflammation. This inflammation can produce a wide range of symptoms and, in extreme cases, cause brain damage, stroke, or even death.
The signs of meningitis may include:
- Sudden fever
- Severe headache
- Nausea or vomiting
- Double vision
- Sensitivity to bright light
- Stiffness in the neck
Meningitis often appears with flu-like symptoms that develop over one to two days. Distinctive rashes are typically seen in some forms of the disease. Meningococcal meningitis may be associated with kidney and adrenal gland failure and shock.
Important signs to watch for in an infant include fever, lethargy, not waking for feedings, vomiting, body stiffness, unexplained/unusual irritability, and a full or bulging fontanel (the soft spot on the top of the head).
Who is more likely to get meningitis?
Anyone—from infants to older adults—can get meningitis. People with weakened immune systems, including those persons with HIV or those taking immunosuppressant drugs, are at increased risk.
Some forms of bacterial meningitis are contagious and can be spread through contact with:
- Nasal discharge
- Respiratory and throat secretions (often spread through kissing, coughing, or sharing drinking glasses, eating utensils, or such personal items as toothbrushes, lipstick, or cigarettes)
For example, people sharing a household, at a day care center, or in a classroom with an infected person can become infected. College students living in dormitories—in particular, college freshmen—have a higher risk of contracting meningococcal meningitis than college students overall. Children who have not been given routine vaccines are at increased risk of developing certain types of bacterial meningitis.
Because the disease can occur suddenly and progress rapidly, anyone who is suspected of having meningitis should immediately contact a doctor or go to the hospital.
Infectious causes of meningitis include bacteria, viruses, fungi, and parasites. For some individuals, environmental exposure (such as a parasite), recent travel, or an immunocompromised state (such as HIV, diabetes, steroids, chemotherapy treatment) are important risk factors. There are also non-infectious causes such as autoimmune/rheumatological diseases and certain medications.
- Bacterial meningitis is a rare but potentially fatal disease. Several types of bacteria can first cause an upper respiratory tract infection and then travel through the bloodstream to the brain. The disease can also occur when certain bacteria invade the meninges directly. Bacterial meningitis can cause stroke, hearing loss, and permanent brain damage.
- Pneumococcal meningitis is the most common form of meningitis and is the most serious form of bacterial meningitis. The disease is caused by the bacterium Streptococcus pneumoniae, which also causes pneumonia, blood poisoning (septicemia), and ear and sinus infections. At particular risk are children under age 2 and adults with a weakened immune system. People who have had pneumococcal meningitis often suffer neurological damage ranging from deafness to severe brain damage. Immunizations are available for certain strains of the pneumococcal bacteria.
- Meningococcal meningitis is caused by the bacterium Neisseria meningitides and is very contagious. High-risk groups include infants under the age of 1 year, people with suppressed immune systems, travelers to foreign countries where the disease is endemic, and college students (freshmen in particular), military recruits, and others who reside in dormitories. Between 10-15 percent of cases are fatal, with another 10-15 percent causing brain damage and other serious side effects. If meningococcal meningitis is diagnosed, people in close contact with an infected individual should be given preventative antibiotics.
- Haemophilus influenzae meningitis was at one time the most common form of bacterial meningitis. Fortunately, the Haemophilus influenzae b vaccine has greatly reduced the number of cases in the United States. Those most at risk of getting this disease are children in child-care settings and children who do not have access to the vaccine.
Other forms of bacterial meningitis include:
- Listeria monocytogenes meningitis (in which certain foods such as unpasteurized dairy or deli meats are sometimes implicated).
- Escherichia coli meningitis, which is most common in elderly adults and newborns and may be transmitted to a baby through the birth canal.
- Mycobacterium tuberculosis meningitis, a rare disease that occurs when the bacterium that causes tuberculosis attacks the meninges.
Viral, or aseptic, meningitis is usually caused by enteroviruses—common viruses that enter the body through the mouth and travel to the brain and surrounding tissues where they multiply. Enteroviruses are present in mucus, saliva, and feces, and can be transmitted through direct contact with an infected person or an infected object or surface. Other viruses that cause meningitis include varicella zoster (the virus that causes chicken pox and can appear decades later as shingles), influenza, mumps, HIV, and herpes simplex type 2 (genital herpes).
Fungal infections can affect the brain. The most common form of fungal meningitis is caused by the fungus cryptococcus neoformans (found mainly in dirt and bird droppings). Cryptococcal meningitis mostly occurs in immunocompromised individuals such as those with AIDS but can also occur in healthy people. Some of these cases can be slow to develop and smolder for weeks. Although treatable, fungal meningitis often recurs in nearly half of affected persons.
Parasitic causes include cysticercosis (a tapeworm infection in the brain), which is common in other parts of the world, as well as cerebral malaria.
There are rare cases of amoebic meningitis, sometimes related to freshwater swimming, which can be rapidly fatal.
How is meningitis diagnosed and treated?
Following a physical exam and medical history to review activities of the past several days or weeks (such as recent exposure to insects, ticks or animals, any contact with ill persons, or recent travel; preexisting medical conditions and medications), the doctor may order various diagnostic tests to confirm the presence of infection or inflammation. Early diagnosis is vital, as symptoms can appear suddenly and escalate to brain damage, hearing and/or speech loss, blindness, or even death.
Diagnostic tests include:
- A neurological examination involves a series of physical examination tests designed to assess motor and sensory function, nerve function, hearing and speech, vision, coordination and balance, mental status, and changes in mood or behavior.
- Laboratory screening of blood, urine, and body secretions can help detect and identify brain and/or spinal cord infection and determine the presence of antibodies and foreign proteins. Such tests can also rule out metabolic conditions that may have similar symptoms.
- Analysis of the cerebrospinal fluid that surrounds and protects the brain and spinal cord can detect infections in the brain and/or spinal cord, acute and chronic inflammation, and other diseases. A small amount of cerebrospinal fluid is removed by a special needle that is inserted into the lower back and the fluid is tested to detect the presence of bacteria, blood, and viruses. The testing can also measure glucose levels (a low glucose level can be seen in bacterial or fungal meningitis) and white blood cells (elevated white blood cell counts are a sign of inflammation), as well as protein and antibody levels.
- Computed tomography, also known as a CT scan
- Magnetic resonance imaging (MRI)
Additionally, electroencephalography, or EEG, can identify abnormal brain waves by monitoring electrical activity in the brain.
People who are suspected of having meningitis should receive immediate, aggressive medical treatment. The disease can progress quickly and has the potential to cause severe, irreversible neurological damage.
Early treatment of bacterial meningitis involves antibiotics that can cross the blood-brain barrier (a lining of cells that keeps harmful micro-organisms and chemicals from entering the brain). Appropriate antibiotic treatment for most types of meningitis can greatly reduce the risk of dying from the disease. Anticonvulsants to prevent seizures and corticosteroids to reduce brain inflammation may be prescribed.
Infected sinuses may need to be drained. Corticosteroids such as prednisone may be ordered to relieve brain pressure and swelling and to prevent hearing loss that is common in Haemophilus influenza meningitis. Lyme disease is treated with antibiotics.
Antibiotics, developed to kill bacteria, are not effective against viruses. Fortunately, viral meningitis is rarely life threatening and no specific treatment is needed. Fungal meningitis is treated with intravenous antifungal medications.
People should avoid sharing food, utensils, glasses, and other objects with someone who may be exposed to or have the infection. People should wash their hands often with soap and rinse under running water.
Effective vaccines are available to prevent Haemophilus influenza, pneumococcal and meningococcal meningitis.
People who live, work, or go to school with someone who has been diagnosed with bacterial meningitis may be asked to take antibiotics for a few days as a preventive measure.
To lessen the risk of being bitten by an infected mosquito or other arthropod, people should:
- Limit outdoor activities at night
- Wear long-sleeved clothing when outdoors
- Use insect repellents that are most effective for that particular region of the country
- Rid lawn and outdoor areas of free-standing pools of water where mosquitoes like to breed
Repellants should not be overapplied, particularly on young children and especially infants, as chemicals like DEET may be absorbed through the skin.
The outlook for individuals with meningitis generally depends on the particular infectious agent involved, the severity of the illness, and how quickly treatment is given. In most cases, people with very mild meningitis can make a full recovery, although the process may be slow.
Individuals who experience only headache, fever, and stiff neck may recover in two to four weeks. Individuals with bacterial meningitis typically show some relief 48-72 hours following initial treatment but are more likely to experience complications caused by the disease. In more serious cases, the disease can cause hearing and/or speech loss, blindness, permanent brain and nerve damage, behavioral changes, cognitive disabilities, lack of muscle control, seizures, and memory loss. These individuals may need long-term therapy, medication, and supportive care.
How can I or my loved one help improve care for people with meningitis?
Consider participating in a clinical trial so clinicians and scientists can learn more about meningitis and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.
All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.
Where can I find more information about meningitis?
Information may be available from the following resources:
Meningitis Foundation of America, Inc.
National Meningitis Association
National Institute of Allergy and Infectious Disease (NIAID)