Meningitis is an inflammation of the membranes (meninges) and cerebrospinal fluid surrounding your brain and spinal cord, usually due to the spread of an infection.
In the past, most meningitis cases occurred in children younger than 5 years. But as a result of the protection offered by current childhood vaccines, most meningitis cases now occur in young people between the ages of 15 and 24. Older adults also tend to have a higher incidence of meningitis than do young children.
The cause of most cases of meningitis is a viral infection, but bacterial and fungal infections also can lead to meningitis. The severity of the inflammation and the best treatment depend on the cause of the infection. Bacterial meningitis is generally much more serious than viral meningitis, and timely treatment is necessary.
Left untreated, bacterial meningitis can be fatal. If you suspect that you or someone in your family has signs or symptoms of meningitis, seek medical care right away. There’s no way to tell what kind of meningitis you have without seeing your doctor and undergoing testing.
Signs and symptoms
It’s easy to mistake the early signs and symptoms of meningitis for the flu. They may develop over a period of one or two days and typically include:
- A high fever
- Severe headache
- Vomiting or nausea with headache
- Confusion, or difficulty concentrating — in the very young, this may appear as inability to maintain eye contact
- Sleepiness or difficulty waking up
- Stiff neck
- Sensitivity to light
- Lack of interest in drinking and eating
- Skin rash in some cases, such as in viral or meningococcal meningitis
Earlier signs and symptoms that may suggest a serious infection, although not necessarily meningitis, include leg pain, ice-cold hands and feet, and abnormally pale skin tone.
Signs in newborns
Newborns and young infants may not have the classic signs and symptoms of headache and stiff neck. Instead, they may cry constantly, seem unusually sleepy or irritable, and eat poorly. Sometimes the soft spots on an infant’s head may bulge. A very late sign may be a spasm consisting of extreme hyperextension of the body (opisthotonos). Young infants may prefer to lie in bed rather than be held.
If you or your child has bacterial meningitis, delaying treatment increases the risk of permanent brain damage. In addition, bacterial meningitis can prove fatal in a matter of days. Seek medical care right away if you or anyone in your family has any signs or symptoms.
Meningitis usually results from a viral infection, but the cause also may be a bacterial infection. Less commonly, a fungal infection may cause meningitis. Because bacterial infections are the most damaging, identifying the source of the infection is an important part of developing a treatment plan.
Acute bacterial meningitis usually occurs when bacteria enter the bloodstream and migrate to the brain and spinal cord. But it can also occur when bacteria invade the meninges directly, as a result of an ear or sinus infection or a skull fracture.
A number of strains of bacteria can cause acute bacterial meningitis. The most common include:
- Streptococcus pneumoniae (pneumococcus). This bacterium is the most common cause of bacterial meningitis in infants and young children in the United States. It can also cause pneumonia and ear and sinus infections. When pneumococcal meningitis is associated with an ear infection, it’s not always clear which came first — the meningitis or the ear infection — because they usually occur together.
- Neisseria meningitidis (meningococcus). This bacterium is another leading cause of bacterial meningitis. Meningococcal meningitis commonly occurs when bacteria from an upper respiratory infection enter your bloodstream. This infection is highly contagious and may cause local epidemics in college dormitories and boarding schools and on military bases.
- Haemophilus influenzae (haemophilus). Before the 1990s, Haemophilus influenzae type b (Hib) bacterium was the leading cause of bacterial meningitis. But new Hib vaccines — available as part of the routine childhood immunization schedule in the United States — have greatly reduced the number of cases of this type of meningitis. When it occurs, it tends to follow an upper respiratory infection, ear infection (otitis media) or sinusitis.
- Listeria monocytogenes (listeria). These bacteria can be found almost anywhere — in soil, in dust and in foods that have become contaminated. Contaminated foods have included soft cheeses, hot dogs and luncheon meats. Many wild and domestic animals also carry the bacteria. Fortunately, most healthy people exposed to listeria don’t become ill, although pregnant women, newborns and older adults tend to be more susceptible. Listeria can cross the placental barrier, and infections in late pregnancy may cause a baby to be stillborn or die shortly after birth.
Viruses cause a greater number of cases of meningitis each year than do bacteria. Viral meningitis is usually mild and often clears on its own in 10 days or less. A group of common viruses known as enteroviruses, which cause stomach flu, are responsible for about 90 percent of viral meningitis in the United States.
The most common signs and symptoms of enteroviral infections are rash, sore throat, joint aches and headache. Many older children and adults with enteroviral meningitis describe the “worst headache I’ve ever had.” These viruses tend to circulate in late summer and early fall. Viruses associated with mumps, herpes infection, West Nile virus or other diseases also can cause viral meningitis.
Ongoing (chronic) forms of meningitis occur when slow-growing organisms invade the membranes and fluid surrounding your brain. Although acute meningitis strikes suddenly, chronic meningitis develops over four weeks or more. Nevertheless, the signs and symptoms of chronic meningitis — headaches, fever, vomiting and mental cloudiness — are similar to those of acute meningitis. This type of meningitis is rare.
Fungal meningitis is relatively uncommon. Cryptococcal meningitis is a 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.
Meningitis can also result from noninfectious causes, such as drug allergies, some types of cancer and inflammatory diseases such as lupus.
Meningitis Risk factors
Not completing the childhood vaccine schedule increases your risk of meningitis. So do a few other risk factors:
- Age. Children younger than 5 years, young people ages 15 to 24 and older adults are more likely to develop meningitis than is the rest of the population.
- 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 increased risk of meningococcal meningitis, probably because infectious diseases tend to spread quickly wherever large groups of people congregate.
- Pregnancy. If you’re pregnant, you’re more likely to contract listeriosis — an infection caused by listeria bacteria, which may also cause meningitis. If you have listeriosis, your unborn baby is at risk, too.
- Working with animals. People who work with domestic animals, including dairy farmers and ranchers, have a higher risk of contracting listeria, which can lead to meningitis.
- Compromised immune system. Factors that may compromise your immune system — including AIDS, diabetes and use of immunosuppressant drugs — also make you more susceptible to meningitis. Removal of your spleen, an important part of your immune system, also may increase your risk.
When to seek medical advice
If you or someone in your family has signs or symptoms of meningitis — such as fever, severe headache, confusion, vomiting and stiff neck — seek medical care right away. There’s no way to know what kind of meningitis you or your child has without seeing your doctor and undergoing testing.
Viral meningitis may improve without treatment in a few days, but bacterial meningitis can be serious and can come on very quickly. If you or your child has bacterial meningitis, the sooner the treatment begins, the better the chances of a recovery without serious complications.
Also talk to your doctor if a family member or someone you work with has meningitis. You may need to take medications to prevent getting sick.
The complications of meningitis can be severe. The longer you or your child has the disease without treatment, the greater the risk of seizures and of permanent neurological damage, including hearing loss, blindness, loss of speech, learning disabilities, behavior problems and brain damage, even paralysis.
Non-neurological complications may include kidney failure and adrenal gland failure. Your adrenal glands produce a number of important hormones including cortisol, which helps your body deal with stress.
Bacterial infections of your central nervous system progress quickly. Within a matter of days, the disease can lead to shock and death.
Screening and 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:
- Throat culture. A throat culture can find and identify the bacteria causing throat pain, neck pain and headache, but can’t determine what pathogens may be in your spinal fluid.
- Imaging. X-rays and computerized tomography (CT) scans of the chest, skull or sinuses may reveal swelling or inflammation. These tests can also help your doctor look for infection in other areas of the body that may be associated with meningitis.
- Spinal tap (lumbar puncture). The definitive diagnosis of meningitis is often made by analyzing a sample of your cerebrospinal fluid (CSF), which is collected during a procedure known as a spinal tap. In people with meningitis, the CSF fluid 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 the exact bacterium that’s causing the illness. Traditionally, it can take up to a week to get these test results. In March 2007, the Food and Drug Administration approved the Xpert EV test, a test that takes only two and one-half hours. This test identifies any genetic material in the CSF from a class of viruses responsible for approximately 90 percent of viral meningitis cases. A positive test tells your doctor you likely have viral meningitis, and a negative test strongly suggests no viral meningitis, making the less common bacterial form of meningitis more likely. This can help those with viral meningitis avoid unnecessary treatment with antibiotics.
- Polymerase chain reaction analysis. If your doctor suspects meningitis, he or she may order a DNA-based test known as a polymerase chain reaction (PCR) amplification to check for the presence of certain causes of meningitis.
If you have chronic meningitis caused by cancer or an inflammatory illness, you may need additional tests.
Acute bacterial meningitis requires prompt treatment with intravenous antibiotics to ensure recovery and reduce the risk of complications. The antibiotic or combination of antibiotics that your doctor may choose depends on the type of bacteria causing the infection. Often, analyzing a sample of cerebrospinal fluid can help identify the bacteria. If you or your child has bacterial meningitis, your doctor may recommend a broad-spectrum antibiotic until he or she can determine the exact cause of the meningitis.
If you or your child has bacterial meningitis, your doctor may recommend treatments for brain swelling, shock, convulsions or dehydration. Infected sinuses or mastoids — the bones behind the outer ear that connect to the middle ear — may need to be drained. Any fluid that has accumulated between the brain and the membranes that surround it may also need to be drained or surgically removed.
Antibiotics can’t cure most viral meningitis, but many cases improve on their own in a week or so without therapy. Treatment of mild cases of viral meningitis is usually with bed rest, plenty of fluids and over-the-counter pain medications to help reduce fever and relieve body aches. If the cause of your meningitis is the herpes virus, your doctor may also recommend an antiviral medication aimed at this virus.
Meningitis typically results from contagious infections. Common bacteria or viruses that can cause meningitis can spread through coughing, sneezing, kissing or sharing eating utensils, a toothbrush or a cigarette. You’re also at increased risk if you live or work with someone who has the disease.
Careful hand washing is important to avoiding exposure to infectious agents. Teach your children to wash their hands often, especially before they eat and after using the toilet, spending time in a crowded public place or petting animals. Show them how to wash their hands vigorously, covering both the front and back of each hand with soap and rinsing thoroughly under running water. In addition, maintain your immune system by getting enough rest, exercising regularly, and eating a healthy diet with plenty of fresh fruits, vegetables and whole grains.
If you’re pregnant, reduce your risk of listeriosis by cooking meat thoroughly and avoiding cheeses made from unpasteurized milk.
Some forms of bacterial meningitis are preventable with the following vaccinations:
- Haemophilus influenzae type b (Hib) vaccine. Children in the United States routinely receive this vaccine as part of the recommended schedule of vaccines, 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 (PCV7). This vaccine is also part of the regular immunization schedule for children younger than 2 years in the United States. In addition, it’s 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 (PPV). Older children and adults who need protection from pneumococcal bacteria may receive this vaccine. The Centers for Disease Control and Prevention recommends the PPV vaccine for all adults older than 65 and younger adults and children who have weak immune systems, chronic illnesses such as heart disease, diabetes or sickle cell anemia, and those who don’t have a spleen.
- Meningococcal conjugate vaccine (MCV4). The Centers for Disease Control and Prevention recommends that a single dose of MCV4 be given to children ages 11 to 12 or to any children ages 11 to 18 who haven’t yet been vaccinated. However, this vaccine can be given to younger children who are at high risk of bacterial meningitis or who have been exposed to someone with the disease. It is approved for use in children as young as 2 years old.