Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges.
The most common symptoms are fever, headache and neck stiffness. Other symptoms include confusion or altered consciousness, vomiting, and an inability to tolerate light or loud noises.
Young children often exhibit only nonspecific symptoms, such as irritability, drowsiness, or poor feeding. ] If a rash is present, it may indicate a particular cause of meningitis; for instance, meningitis caused by meningococcal bacteria may be accompanied by a characteristic rash.
The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs. Meningitis can be life-threatening because of the inflammation’s proximity to the brain and spinal cord; therefore, the condition is classified as a medical emergency.
A lumbar puncture diagnoses or excludes meningitis. A needle is inserted into the spinal canal to collect a sample of cerebrospinal fluid (CSF) that envelops the brain and spinal cord. The CSF is examined in a medical laboratory.
Some forms of meningitis are preventable by immunization with the meningococcal, mumps, pneumococcal, and Hib vaccines. Giving antibiotics to people with significant exposure to certain types of meningitis may also be useful.
The first treatment in acute meningitis consists of promptly giving antibiotics and sometimes antiviral drugs. Corticosteroids can also be used to prevent complications from excessive inflammation.
Meningitis can lead to serious long-term consequences such as deafness, epilepsy, hydrocephalus, or cognitive deficits, especially if not treated quickly.
In 2013 meningitis occurred in about 16 million people worldwide. This resulted in 303,000 deaths – down from 464,000 deaths in 1990. With appropriate treatment the risk of death in bacterial meningitis is less than 15%. Outbreaks of bacterial meningitis occur between December and June each year in an area of sub-Saharan Africa known as the meningitis belt. Smaller outbreaks may also occur in other areas of the world.
Symptoms and causes
Early meningitis symptoms may mimic the flu (influenza). Symptoms may develop over several hours or over a few days.
Possible signs and symptoms in anyone older than the age of 2 include:
Sudden high fever
Severe headache that seems different than normal
Headache with nausea or vomiting
Confusion or difficulty concentrating
Sleepiness or difficulty waking
Sensitivity to light
No appetite or thirst
Skin rash (sometimes, such as in meningococcal meningitis)
Signs in new-borns
New-borns and infants may show these signs:
Excessive sleepiness or irritability
Inactivity or sluggishness
A bulge in the soft spot on top of a baby’s head (fontanel)
Stiffness in a baby’s body and neck
Infants with meningitis may be difficult to comfort, and may even cry harder when held.
When to see a doctor
Seek immediate medical care if you or someone in your family has meningitis symptoms, such as:
Severe, unrelenting headache
Bacterial meningitis is serious, and can be fatal within days without prompt antibiotic treatment. Delayed treatment increases the risk of permanent brain damage or death.
It’s also important to talk to your doctor if a family member or someone you work with has meningitis. You may need to take medications to prevent getting the infection.
Causes of Meningitis
Viral infections are the most common cause of meningitis, followed by bacterial infections and, rarely, fungal infections. Because bacterial infections can be life-threatening, identifying the cause is essential.
Bacteria that enter the bloodstream and travel to the brain and spinal cord cause acute bacterial meningitis. But it can also occur when bacteria directly invade the meninges. This may be caused by an ear or sinus infection, a skull fracture, or, rarely, after some surgeries.
Several strains of bacteria can cause acute bacterial meningitis, most commonly:
- Streptococcus pneumoniae (pneumococcus). This bacterium is the most common cause of bacterial meningitis in infants, young children and adults in the United States. It more commonly causes pneumonia or ear or sinus infections. A vaccine can help prevent this infection.
- Neisseria meningitides.
- This bacterium is another leading cause of bacterial meningitis. These bacteria commonly cause an upper respiratory infection but can cause meningococcal meningitis when they enter the bloodstream. This is a highly contagious infection that affects mainly teenagers and young adults. It may cause local epidemics in college dormitories, boarding schools and military bases. A vaccine can help prevent infection.
- Haemophilus influenza. Haemophilus influenza type b (Hib) bacterium was once the leading cause of bacterial meningitis in children. But new Hib vaccines have greatly reduced the number of cases of this type of meningitis.
- Listeria monocytogenes (listeria). These bacteria can be found in unpasteurized cheeses, hot dogs and luncheon meats. Pregnant women, new-borns, older adults and people with weakened immune systems are most susceptible. Listeria can cross the placental barrier, and infections in late pregnancy may be fatal to the baby.
Viral meningitis is usually mild and often clears on its own. Most cases in the United States are caused by a group of viruses known as enteroviruses, which are most common in late summer and early fall. Viruses such as herpes simplex virus, HIV, mumps, West Nile virus and others also can cause viral meningitis.
Slow-growing organisms (such as fungi and Mycobacterium tuberculosis) that invade the membranes and fluid surrounding your brain cause chronic meningitis. Chronic meningitis develops over two weeks or more. The symptoms of chronic meningitis — headaches, fever, vomiting and mental cloudiness — are similar to those of acute meningitis.
Fungal meningitis is relatively uncommon and causes chronic meningitis. It may mimic acute bacterial meningitis. Fungal meningitis isn’t contagious from person to person. Cryptococci meningitis is a common fungal form of the disease that affects people with immune deficiencies, such as AIDS. It’s life-threatening if not treated with an antifungal medication.
Other meningitis causes
Meningitis can also result from non-infectious causes, such as chemical reactions, drug allergies, some types of cancer and inflammatory diseases such as sarcoidosis.
Risk factors for meningitis include:
- Skipping vaccinations. Risk rises for anyone who hasn’t completed the recommended childhood or adult vaccination schedule.
- Age. Most cases of viral meningitis occur in children younger than age 5. Bacterial meningitis is common in those under age 20.
- Living in a community setting. College students living in dormitories, personnel on military bases, and children in boarding schools and child care facilities are at greater risk of meningococcal meningitis. This is probably because the bacterium is spread by the respiratory route, and spreads quickly through large groups.
- Pregnancy. Pregnancy increases the risk of listeriotic — an infection caused by listeria bacteria, which also may cause meningitis. Listeriotic increases the risk of miscarriage, stillbirth and premature delivery.
- Compromised immune system. AIDS, alcoholism, diabetes, use of immunosuppressant drugs and other factors that affect your immune system also make you more susceptible to meningitis. Having your spleen removed also increases your risk, and patients without a spleen should get vaccinated to minimize that risk.
Meningitis complications can be severe. The longer you or your child has the disease without treatment, the greater the risk of seizures and permanent neurological damage, including:
- Hearing loss
- Memory difficulty
- Learning disabilities
- Brain damage
- Gait problems
- Kidney failure
With prompt treatment, even patients with severe meningitis can have good recovery.
For some causes of meningitis, protection can be provided in the long term through vaccination, or in the short term with antibiotics. Some behavioral measures may also be effective.
How to avoid meningitis
You can reduce your risk of getting or spreading viruses and bacteria by taking a few precautions:
- Wash your hands frequently with warm water and soap. Wash for a full 20 seconds, taking care to clean under fingernails. Rinse and dry thoroughly.
- Wash your hands before eating, after using the toilet, after changing a diaper, or after tending to someone who is ill.
- Don’t share eating utensils, straws, or plates.
- Cover your nose and mouth when you cough or sneeze.
- Stay up to date with immunizations and booster shots for meningitis.
- Ask your doctor about immunizations before traveling to countries with higher rates of meningitis.
If you have signs of meningitis, seek medical attention immediately.