What is Meningitis?

Meningitis is an inflammation of the membranes (meninges) surrounding your brain and spinal cord.

The swelling from meningitis typically triggers symptoms such as headache, fever and a stiff neck.

Most cases of meningitis are caused by a viral infection, but bacterial and fungal infections are other causes. Some cases of meningitis improve without treatment in a few weeks. Others can be life-threatening and require emergent antibiotic treatment.

Seek immediate medical care if you suspect that someone has meningitis. Early treatment of bacterial meningitis can prevent serious complications.

Symptoms

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
• Stiff neck
• Severe headache that seems different than normal
• Headache with nausea or vomiting
• Confusion or difficulty concentrating
• Seizures
• Sleepiness or difficulty waking
• Sensitivity to light
• No appetite or thirst
• Skin rash (sometimes, such as in meningococcal meningitis)

Signs in newborns

Newborns and infants may show these signs:

• High fever
• Constant crying
• Excessive sleepiness or irritability
• Inactivity or sluggishness
• Poor feeding
• 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:

• Fever
• Severe, unrelenting headache
• Confusion
• Vomiting
• Stiff neck

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

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.

Bacterial meningitis

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 meningitidis (meningococcus). 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 influenzae (haemophilus). Haemophilus influenzae 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, newborns, 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

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.

Chronic 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

Fungal meningitis is relatively uncommon and causes chronic meningitis. It may mimic acute bacterial meningitis. Fungal meningitis isn't contagious from person to person. Cryptococcal 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 noninfectious causes, such as chemical reactions, drug allergies, some types of cancer and inflammatory diseases such as sarcoidosis.

Risk factors

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 listeriosis — an infection caused by listeria bacteria, which also may cause meningitis. Listeriosis 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.

Complications

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
• Seizures
• Kidney failure
• Shock
• Death

With prompt treatment, even patients with severe meningitis can have good recovery.

Diagnosis

Your family doctor or pediatrician can diagnose meningitis based on a medical history, a physical exam and certain diagnostic tests. During the exam, your doctor may check for signs of infection around the head, ears, throat and the skin along the spine.

You or your child may undergo the following diagnostic tests:

• Blood cultures. Blood samples are placed in a special dish to see if it grows microorganisms, particularly bacteria. A sample may also be placed on a slide and stained (Gram's stain), then studied under a microscope for bacteria.

• Imaging. Computerized tomography (CT) or magnetic resonance (MR) scans of the head may show swelling or inflammation. X-rays or CT scans of the chest or sinuses may also show infection in other areas that may be associated with meningitis.

• Spinal tap (lumbar puncture). For a definitive diagnosis of meningitis, you'll need a spinal tap to collect cerebrospinal fluid (CSF). In people with meningitis, the CSF often shows a low sugar (glucose) level along with an increased white blood cell count and increased protein.

CSF analysis may also help your doctor identify which bacterium caused the meningitis. If your doctor suspects viral meningitis, he or she may order a DNA-based test known as a polymerase chain reaction (PCR) amplification or a test to check for antibodies against certain viruses to determine the specific cause and determine proper treatment.

Treatment

The treatment depends on the type of meningitis you or your child has.

Bacterial meningitis

Acute bacterial meningitis must be treated immediately with intravenous antibiotics and, more recently, corticosteroids. This helps to ensure recovery and reduce the risk of complications, such as brain swelling and seizures.

The antibiotic or combination of antibiotics depends on the type of bacteria causing the infection. Your doctor may recommend a broad-spectrum antibiotic until he or she can determine the exact cause of the meningitis.

Your doctor may drain any infected sinuses or mastoids — the bones behind the outer ear that connect to the middle ear.

Viral meningitis

Antibiotics can't cure viral meningitis, and most cases improve on their own in several weeks. Treatment of mild cases of viral meningitis usually includes:

• Bed rest
• Plenty of fluids
• Over-the-counter pain medications to help reduce fever and relieve body aches

Your doctor may prescribe corticosteroids to reduce swelling in the brain, and an anticonvulsant medication to control seizures. If a herpes virus caused your meningitis, an antiviral medication is available.

Other types of meningitis

If the cause of your meningitis is unclear, your doctor may start antiviral and antibiotic treatment while the cause is determined.

Chronic meningitis is treated based on the underlying cause. Antifungal medications treat fungal meningitis and a combination of specific antibiotics can treat tuberculous meningitis. However, these medications can have serious side effects, so treatment may be deferred until a laboratory can confirm that the cause is fungal. Chronic meningitis is treated based on the underlying cause.

Noninfectious meningitis due to allergic reaction or autoimmune disease may be treated with corticosteroids. In some cases no treatment may be required, because the condition can resolve on its own. Cancer-related meningitis requires therapy for the individual cancer.