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

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

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

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

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 from 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
• Difficulty waking from sleep
• Inactivity or sluggishness
• Not waking to eat
• Poor feeding
• Vomiting
• A bulge in the soft spot on top of a baby's head (fontanel)
• Stiffness in the 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 signs or 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 live or work with has meningitis. You may need to take medications to prevent getting the infection.

Viral infections are the most common cause of meningitis, followed by bacterial infections and, rarely, fungal and parasitic 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 — 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. Even if vaccinated, anybody who has been in close contact with a person with meningococcal meningitis should receive an oral antibiotic to prevent the disease.
• 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 lunchmeats. 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 virus, 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 signs and symptoms of chronic meningitis — headache, fever, vomiting and mental cloudiness — are similar to those of acute meningitis.

Fungal meningitis

Fungal meningitis is relatively uncommon in the United States. It may mimic acute bacterial meningitis. It's often contracted by breathing in fungal spores that may be found in soil, decaying wood and bird droppings. 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. Even with treatment, fungal meningitis may recur.

Parasitic meningitis

Parasites can cause a rare type of meningitis called eosinophilic meningitis. Parasitic meningitis can also be caused by a tapeworm infection in the brain (cysticercosis) or cerebral malaria. Amoebic meningitis is a rare type that is sometimes contracted through swimming in fresh water and can quickly become life-threatening. The main parasites that cause meningitis typically infect animals. People are usually infected by eating foods contaminated with these parasites. Parasitic meningitis isn't spread between people.

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 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 through the respiratory route, and spreads quickly through large groups.
• Pregnancy. Pregnancy increases the risk of listeriosis — an infection caused by listeria bacteria, which may also 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 anyone 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
• Seizures
• Kidney failure
• Shock
• Death

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

Common bacteria or viruses that can cause meningitis can spread through coughing, sneezing, kissing, or sharing eating utensils, a toothbrush or a cigarette.

These steps can help prevent meningitis:

• Wash your hands. Careful hand-washing helps prevent the spread of germs. Teach children to wash their hands often, especially before eating and after using the toilet, spending time in a crowded public place or petting animals. Show them how to vigorously and thoroughly wash and rinse their hands.
• Practice good hygiene. Don't share drinks, foods, straws, eating utensils, lip balms or toothbrushes with anyone else. Teach children and teens to avoid sharing these items too.
• Stay healthy. Maintain your immune system by getting enough rest, exercising regularly, and eating a healthy diet with plenty of fresh fruits, vegetables and whole grains.
• Cover your mouth. When you need to cough or sneeze, be sure to cover your mouth and nose.
• If you're pregnant, take care with food. Reduce your risk of listeriosis by cooking meat, including hot dogs and deli meat, to 165 F (74 C). Avoid cheeses made from unpasteurized milk. Choose cheeses that are clearly labeled as being made with pasteurized milk.

Vaccinations

Some forms of bacterial meningitis are preventable with the following vaccinations:

• Haemophilus influenzae type b (Hib) vaccine. The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) recommend this vaccine for children starting at about 2 months of age. The vaccine is also recommended for some adults, including those who have sickle cell disease or AIDS and those who don't have a spleen.
• Pneumococcal conjugate vaccine (PCV13). This vaccine also is part of the WHO and CDC recommended routine vaccination schedule for children younger than 2 years. Additional doses are recommended for children between the ages of 2 and 5 who are at high risk of pneumococcal disease, including children who have chronic heart or lung disease or cancer.
• Pneumococcal polysaccharide vaccine (PPSV23). Older children and adults who need protection from pneumococcal bacteria may receive this vaccine. The CDC recommends the PPSV23 vaccine for all adults older than 65; for younger adults and children age 2 and older who have weak immune systems or chronic illnesses such as heart disease, diabetes or sickle cell anemia; and for anyone who doesn't have a spleen.

• Meningococcal conjugate vaccine. The CDC recommends that a single dose be given to children ages 11 to 12, with a booster shot given at age 16. If the vaccine is first given between ages 13 and 15, the booster is recommended between ages 16 and 18. If the first shot is given at age 16 or older, no booster is necessary.

  This vaccine can also be given to children between the ages of 2 months and 10 years who are at high risk of bacterial meningitis or who have been exposed to someone with the disease. It's also used to vaccinate healthy but previously unvaccinated people who have been exposed in outbreaks.

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 skin along the spine.

You or your child may undergo the following diagnostic tests:

• Blood cultures. A blood sample is 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 to see whether bacteria are present.
• Imaging. Computerized tomography (CT) or magnetic resonance imaging (MRI) scans of the head may show swelling or inflammation. X-rays or CT scans of the chest or sinuses also may show infection 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 proper 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 sometimes 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 unknown, your doctor may start antiviral and antibiotic treatment while the cause is determined.

Treatment for chronic meningitis is 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.

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 specific cancer.

Meningitis can be life-threatening, depending on the cause. If you've been exposed to bacterial meningitis and you develop symptoms, go to an emergency room and let medical staff know you may have meningitis.

If you're not sure what you have and you call your doctor for an appointment, here's how to prepare for your visit.

What you can do

• Be aware of any pre- or post-appointment restrictions. Ask if there's anything you need to do in advance, such as restrict your diet. Also ask if you may need to stay at your doctor's office for observation following your tests.
• Write down symptoms you're having, including changes in your mood, thinking or behavior. Note when you developed each symptom and whether you had cold- or flu-like symptoms.
• Write down key personal information, including any recent moves, vacations or interactions with animals. If you're a college student, your doctor likely will ask questions about any similar signs or symptoms in your roommates and dorm mates. Your doctor will also want to know your vaccination history.
• Make a list of all medications, vitamins or supplements you're taking.
• Take a family member or friend along. Meningitis can be a medical emergency. Take someone who can help remember all the information your doctor provides and who can stay with you if needed.
• Write down questions to ask your doctor.

For meningitis, some basic questions to ask your doctor include:

• What kinds of tests do I need?
• What treatment do you recommend?
• Am I at risk of long-term complications?
• If my condition is not treatable with antibiotics, what can I do to help my body recover?
• Am I contagious? Do I need to be isolated?
• What is the risk to my family? Should they take preventive medication?
• Is there a generic alternative to the prescription medicine you're recommending?
• Do you have any printed information I can have? What websites do you recommend?

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

• When did you begin experiencing symptoms?
• How severe are your symptoms? Do they seem to be getting worse?
• Does anything seem to improve your symptoms?
• Have you been exposed to anyone with meningitis?
• Does anyone in your household have similar symptoms?
• What is your vaccination history?
• Do you take any immunosuppressant medications?
• Do you have other health problems, including allergies to any medications?

What you can do in the meantime

When you call your doctor's office for an appointment, describe the type and severity of your symptoms. If your doctor says you don't need to come in immediately, rest as much as possible while you're waiting for your appointment.

Drink plenty of fluids and take acetaminophen (Tylenol, others) to reduce your fever and body aches. Also avoid any medications that may make you less alert. Don't go to work or school.