Meningitis is inflammation of the meninges, which are the membranes that protect the brain and spinal cord. The meninges can be infected by bacteria, viruses or fungi. Rarely, meningitis may also be caused by trauma, some medications, cancers or other diseases. Anyone can develop meningitis, although young children are particularly susceptible to the disease. Children under the age of 2 years are especially vulnerable because their immune systems are not yet fully developed.

Viral (aseptic) meningitis is the most common type of meningitis. It can be serious, and up to 50,000 Americans are hospitalized with it every year, according to the U.S. Centers for Disease Control and Prevention (CDC). However, its symptoms are usually mild, with many cases going unnoticed or undiagnosed. Bacterial meningitis is far less common but tends to be much more dangerous and can be fatal if not treated promptly.

A variety of signs and symptoms (e.g., fever, headache) may indicate a mild meningitis infection, with most subsiding after a few days. Symptoms of a more serious meningitis infection (e.g., seizures, vomiting) require immediate medical attention. In most cases, meningitis can be diagnosed from a medical history, physical examination and certain medical tests (e.g., spinal tap, imaging tests).

Treatment of meningitis is dependent on its type or cause. Common treatments for viral meningitis include over-the-counter medications, rest and drinking plenty of fluids. Bacterial meningitis is typically treated with antibiotics. The combination prescribed depends on a number of factors, including infection source, disease severity and age of the patient.

Vaccinations are available to prevent some forms of bacterial meningitis. In addition to making sure their children have the proper immunizations, parents are urged to instruct children to wash their hands thoroughly, particularly before eating and after using the bathroom. Washing hands regularly and properly kills germs and reduces the risk of being infected with the bacteria and viruses that can lead to meningitis.

Parents of children who exhibit symptoms associated with meningitis are urged to seek prompt medical care. The sooner meningitis is diagnosed and treated, the less severe the health consequences are likely to be.

Meningitis occurs when the meninges, the membranes covering the brain and spinal cord become inflamed. Most cases result from bacterial, viral or fungal infection. Rarely, meningitis may also occur in reaction to physical trauma, or some medications or diseases (e.g., cancer). Anyone can develop meningitis, although young children are particularly susceptible to the disease. Children under the age of 2 years are especially vulnerable to meningitis because their immune systems are not yet fully developed.

Other groups that are especially vulnerable include older adults and individuals with a long-standing health condition (e.g., HIV/AIDS). Though meningitis may be potentially life-threatening, children who have this disease typically make a full recovery when it is diagnosed and treated promptly.

The central nervous system is covered by three membranous layers of connective tissue called meninges. The meninges protect neural tissues of the brain and spinal cord, as well as enable the vertebral column and spinal cord to flex and twist.

The inflexible outermost layer of the meninges is the dura mater. It fuses with the lining of the skull. The middle layer of the meninges is the arachnoid mater. This membrane is separated from the delicate, innermost membrane (pia mater) by a space that contains cerebrospinal fluid (CSF). This fluid carries nutrients, helps absorb impact and helps defend the brain from harmful microorganisms.

In many cases, meningitis stems from bacteria, viruses or fungi that are associated with everyday illnesses. In other cases, infections that result in meningitis begin in places such as the respiratory tract, skin, gastrointestinal tract and urinary system. Bacteria, viruses or fungi reach the meninges through the bloodstream, from nearby infections (e.g., sinusitis) or by direct contact (e.g., penetrating injury, surgical procedure).

While in the bloodstream, these microorganisms resist attack by white blood cells, causing receptors in the brain to allow penetration into the CSF. Once in the CSF, infection tends to progress rapidly because of the lack of disease-fighting substances (antibodies). The resulting inflammation causes exudate (oozing fluid) to damage cranial nerves and pathways that carry signals to other parts of the body. It also causes swelling of the meninges, which disrupts the normal flow of blood and oxygen to the brain.

Parents of children who exhibit symptoms associated with meningitis are urged to seek prompt medical care. The sooner meningitis is diagnosed and treated; the less severe the health consequences are likely to be.

However, the complications associated with meningitis can be severe. Even with effective antimicrobial therapy, significant neurological complications have been reported in some patients following an episode of bacterial meningitis. An increased intracranial pressure (ICP) is a potentially fatal complication. The main sign of increased ICP is an altered state of consciousness, which may vary from lethargy to a state of prolonged unconsciousness, which can rapidly progress to death. Other severe complications include cerebral palsy, mental retardation, blindness, seizures, adrenal gland failure, hearing impairment and/or loss of speech, learning disabilities and behavioral problems.

Most cases of meningitis can be classified as one of the two primary types – viral and bacterial – or a third type known as chronic meningitis:

• Viral (aseptic) meningitis. The most common form of meningitis, it affects all age groups but is especially prevalent in children. The U.S. Centers for Disease Control and Prevention (CDC) estimates that 25,000 to 50,000 Americans are hospitalized with viral meningitis every year. Most patients with viral meningitis, though, have symptoms that go away without any special treatment, and virtually all patients eventually make a complete recovery. However, symptoms of viral meningitis often closely resemble those associated with bacterial meningitis, a much more serious form of the disease that requires immediate treatment. This similarity may complicate the process of diagnosing the source and severity of the infection.
  
  Viral meningitis may be caused by enteroviruses (viruses that infect the intestinal tract, such as those that cause poliomyelitis) or other viral conditions (e.g., herpes simplex virus, human immunodeficiency virus). At least 20 viruses cause viral meningitis. At one time, mumps was a major cause of viral meningitis. However, immunization with the measles, mumps and rubella (MMR) vaccine has reduced such infections significantly.
  
  
• Bacterial meningitis. Usually the most severe type of meningitis, it is less common than viral meningitis and more likely to be life-threatening. Infants, young children and the elderly are most at risk. College students and others who spend time in close quarters with others (e.g., childcare facilities, dormitories, military units) also are at higher risk.
  
  Many types of bacteria can cause bacterial meningitis if they travel through the bloodstream and enter the brain. The most common causes of bacterial meningitis in newborns include Group B Streptococcus (GBS), Escherichia coli (E. coli) and Listeria monocytogenes. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) bacteria are more common in children older than 2 months of age. At one time, Haemophilus influenzae type B (Hib) was the leading cause of meningitis in children. However, use of the Hib vaccine has sharply curtailed this type of infection.
  
  According to the CDC, about 6,000 people develop pneumococcal meningitis and 2,600 people develop meningococcal meningitis in the United States each year. Vaccines are available that can prevent some types of bacterial meningitis from spreading to other people. The disease can also occur if bacteria invade the meninges directly, such as from a nearby ear infection or sinus infection (sinusitis) or from a severe head injury such as a skull fracture. Left untreated, bacterial meningitis may cause brain damage, deafness, visual impairment, seizures, cognitive impairment (including learning disabilities) and can even be fatal. The adrenal glands, heart and kidneys also may be affected.
  
  
• Chronic meningitis. Inflammation of the meninges that is ongoing or recurrent. Children with chronic meningitis experience spontaneous episodes of severe headache and fever, often interrupted by extended periods without painful symptoms. Chronic meningitis has no known underlying cause, though it occurs relatively frequently in people with compromised immune systems (e.g., individuals with HIV/AIDS).

Meningitis is usually caused by bacteria or a viral infection, although it may also be caused by some fungal infections. Children under the age of 5 years, adults between the ages of 18 and 24 years, people who live in community settings (e.g., college dormitories) patients with compromised immune systems due to chronic illnesses (e.g., diabetes, AIDS), pregnant women and people who work with animals (e.g., ranchers) have increased risk of exposure to the causes of the disease.

Viral (aseptic) meningitis is the most common type of meningitis. However, symptoms of viral meningitis tend to be very mild, with many cases going unnoticed or undiagnosed.

The viral form of the disease may be spread in several ways (e.g., poor hygiene, polluted water or sewage). However, contact with a person who has viral meningitis may not necessarily lead to the development of meningitis. Although the initial virus (e.g., chickenpox) may be infectious, it will not necessarily result in viral meningitis.  

Many viruses may cause viral meningitis. The most common include:

• Enteroviruses. The most common cause of viral meningitis. Enteroviruses (e.g., coxsackie virus, polio virus, echovirus) live in human intestines and are usually spread through biological matter (e.g., saliva, feces, mucus). However, most produce only mild symptoms (e.g., sore throat, cold) with only a very small percentage of infections resulting in the development of meningitis. Exposure to enteroviruses tends to occur in the warmer summer months.
  
  
• Herpes simplex virus (HSV). Both HSV-1 (virus that causes cold sores) and HSV-2 (virus that causes genital herpes) can cause meningitis in rare instances. HSV-2 is the leading cause of recurrent infection (Mollaret’s meningitis).
  
  
• Human immunodeficiency virus (HIV). Patients with HIV may occasionally develop meningitis or meningoencephalitis (meningitis accompanied by encephalitis, inflammation of the brain). This can be due to a suppressed immune system or direct HIV infection of the central nervous system. Most patients with this form of viral meningitis experience mild symptoms (e.g., headache, rash).
  
  
• Mumps and measles. May cause meningitis as well as encephalitis. Cases of meningitis resulting from mumps or measles are extremely rare because of the success of routine childhood vaccinations for these diseases.

Other common viruses may occasionally cause viral meningitis (e.g., arboviruses that cause Lyme disease, chickenpox, infectious mononucleosis). Recently, the spread of West Nile virus through mosquito bites has created a new source of viral meningitis in the United States.

Bacterial meningitis is far less common than viral meningitis, although it can occur very quickly and tends to be much more dangerous. It can spread from person to person and needs contact isolation. Some of the more common causes of bacterial meningitis include:

• Streptococcus pneumoniae (pneumococcal). The bacteria that causes pneumonia. This is the most common cause of bacterial meningitis in adults. Although it occurs rarely, pneumococcal meningitis has a fatality rate of about 20 percent, according to the National Institutes of Health (NIH). Furthermore, about half of all who recover have serious long-term complications (e.g., deafness, epilepsy) as well.
  
  
• Neisseria meningitides (meningococcal). A relatively frequent cause of meningitis. According to the NIH, about 10 percent of cases are fatal. However, many people who carry these bacteria never develop signs or symptoms of meningitis. These bacteria live naturally in the back of the nose, throat and upper respiratory areas of the human body. They pass between people through personal contact (e.g., touching, kissing) and by coughing or sneezing. Meningococcal bacteria cannot live outside of the body, making contagious outbreaks rare. Septicemia (blood poisoning) occasionally occurs in conjunction with meningitis when meningococcal bacteria enter the bloodstream (meningococcemia).
  
  
• Haemophilus influenzae b (Hib). Formerly the most common cause of bacterial meningitis. The recent development of a Hib vaccine has reduced instances of haemophilus meningitis substantially, with very few cases reported annually.
  
  
• Listeria monocytogenes (listeriosis). Meningitis may occur as a result of listeriosis (infection caused by eating contaminated food). This type of meningitis is most frequent in pregnant women, their fetuses, newborns and adults with weakened immune systems.
  
  
• E. coli (Escherichia coli). Bacteria that live in the colon or large intestine of healthy people. E. coli meningitis usually affects people with suppressed immune systems (e.g., cancer patients, AIDS patients). Because these bacteria may be present in the birth canal of pregnant women, some newborns (e.g., premature babies, low-birth weight babies) may have a higher risk of becoming infected during delivery.
  
  
• Bacillus tubercle (tuberculosis). A rare form of meningitis may occasionally occur when the bacterium that causes tuberculosis spreads from the lungs, attacking the meninges (membranes that cover the brain and spinal cord).
  
  
• Cochlear implants. Special hearing devices placed surgically in people with hearing loss. Rarely, bacterial meningitis may occur in people who receive cochlear implants. This may stem from a number of factors (e.g., inner ear abnormalities, surgical complications, history of ear infections).

In addition, some fungi (e.g., cryptococcus, histoplasma) may occasionally cause meningitis. This is rare, however, and usually occurs in patients whose immune systems are severely weakened from disease (e.g., HIV, AIDS, cancer) or in young children. Pools of standing water may carry amoebas that can cause a very rare but serious form of infection. Finally, traumatic injuries, drug allergies, some types of cancer and inflammatory diseases such as lupus can cause some types of meningitis.

Meningitis is a rare but potentially serious and fatal disease that requires emergency medical attention. Although viral meningitis tends to be less dangerous than bacterial meningitis, the two conditions often share the same initial symptoms, making early diagnosis crucial.

Symptoms of meningitis infection may appear in as little as 24 hours after infection, which typically follows a cold, runny nose, or diarrhea and vomiting. In many cases, though, symptoms do not appear for anywhere from two days to two weeks.

In some cases, newborns and infants exhibit few signs of meningitis apart from irritability and lethargy. Young children with meningitis sometimes display a symptom known as paradoxical irritability, in which they become even more distressed when picked up and rocked by an adult. Other symptoms sometimes associated with meningitis in newborns and infants include:

• Jaundice (yellowing of the skin, whites of the eyes and mucous membranes)
  
  
• Neck rigidity
  
  
• Mild fever, or lower-than-normal temperature
  
  
• Poor eating or a weak sucking reflex
  
  
• High-pitched cry
  
  
• Bulging of the soft spot (fontanelle) on top of the skull
  
  
• Spasm causing extreme hyperextension of the body (opisthotonos) late in the disease

Symptoms of meningitis differ in older children and adults. They may include:

• Fever
• Headache
• Confusion or disorientation
• Stiff or painful neck
• Muscle aches or weakness
• Nausea and vomiting
• Seizures
• Sluggishness
• Sensitivity to light (photophobia)
• Skin rash (e.g., viral or meningococcal meningitis)

As symptoms unfold, they tend to be milder in cases of viral meningitis than they are in cases of bacterial meningitis.

Parents are urged to seek immediate emergency medical attention if their child has difficulty breathing (especially if the child turns blue), lapses into a coma or experiences a seizure.

A physician should also be consulted if a child is under 6 months old and has a fever of 100.2 degrees Fahrenheit (37.9 degrees Celsius), is over 6 months old and has a fever of 102 degrees Fahrenheit (38.9 degrees Celsius), has a fever and stiff neck and is vomiting, has a headache that progressively worsens, becomes increasingly drowsy or has a fever and rash and is confused or lethargic. Parents also should consult a physician if their child has a playmate who has been diagnosed with meningitis.

To diagnose meningitis, a physician will review a child’s medical history and perform a physical examination. Certain medical tests may also be performed, including:

• Spinal tap. The insertion of a long needle into the spinal canal to collect cerebrospinal fluid (CSF) for laboratory testing. Analysis of CSF is the only definitive diagnosis method of meningitis. CSF is checked for indicators of an infection (e.g., the number of white blood cells, glucose and protein levels) and then analyzed by a physician to determine if meningitis is present. CSF may also help identify if the source of infection is bacterial or viral. A spinal tap is nearly always performed if meningitis infection is suspected.
  
  
• Throat culture. The back of the throat is swabbed and examined under a microscope. A throat culture can determine if the presence of microorganisms that can cause meningitis or a disease with similar symptoms (e.g., encephalitis) are present. In addition, it may also be helpful in determining the appropriate course of treatment.
  
  
• Imaging tests. Tests that produce images of internal body organs, tissues, structures and pathways (e.g., x-ray, CAT scan, MRI). Imaging tests of certain parts of the body (e.g., chest, skull) may show swelling or inflammation consistent with meningitis and the severity of the infection.
  
  
• Urine tests. Urine may be tested to check for the source of infection.
  
  
• Blood tests. Blood may be analyzed to check counts of white and red blood cells and biochemistry (hormone levels). Cultures of blood can be developed that can be examined for the presence of bacteria or viruses.
  
  
• Polymerase chain reaction (PCR). A process that checks blood for the presence of viruses or parasites. A PCR may be performed if a child is suspected of having meningitis.
  
  
• Biopsy.  Rarely, a sample of tissue from a rash thought to be caused by meningitis may be removed for laboratory analysis.

Treatment of meningitis depends on its type or cause. For example, viral meningitis may sometimes resolve on its own within several days, but viral meningitis caused by herpes simplex virus (HSV) may require antiviral medication. Over-the-counter medication (e.g., analgesics) is also often used to alleviate symptoms of viral meningitis. Other common treatments include rest and drinking fluids.

Although bacterial meningitis is less common than viral meningitis, it is potentially much more dangerous. It requires prompt treatment under a physician’s supervision. Antibiotics will be prescribed to treat bacterial meningitis, and the child will no longer be contagious about 24 hours after beginning antibiotic therapy.

The combination of medications prescribed to treat meningitis depends on a number of factors, including:

• Source of infection (e.g., type of bacteria)
• Age of the patient
• Severity of infection
• Presence of other medical conditions or complications

A physician will often begin administering intravenous antibiotics before the cause has been determined because of the possibility of severe complications from the disease. Treatment may be altered or stopped later if testing indicates a viral infection as the source of meningitis.

A physician may also prescribe treatments to deal with symptoms of the disease (e.g., brain swelling, convulsions and dehydration). Fluid that has accumulated in and around the brain may be drained or otherwise removed. Analgesics or nonsteroidal anti-inflammatory drugs (NSAIDs) may be administered to reduce pain and/or inflammation. Steroids are also used in certain cases of bacterial meningitis.

Following treatment, bacterial meningitis can take anywhere from a few days to several weeks to fully resolve. Viral meningitis tends to resolve in less than two weeks.

Though meningitis itself is not contagious, bacteria that cause infection which may lead to meningitis may be spread through:

• Personal contact (e.g., touching, kissing)
• Coughing or sneezing
• Sharing certain personal items (e.g., toothbrush, eating utensils)

Living with someone who has meningitis may also increase the risk of bacterial exposure. In some cases, a physician may prescribe antibiotics as a preventive measure for people living with someone who is infected. Vaccinations are also available to prevent some forms of bacterial meningitis, including:

• Meningococcal conjugate vaccine (MCV4). Expected to give better, longer-lasting protection than previous meningitis vaccines. Licensed in 2005, MCV4 is also predicted to prevent person-to-person spread of meningitis. The U.S. Centers for Disease Control and Prevention (CDC) recommends this vaccine for children at their routine adolescent visit (11 or 12 years of age) and other people at increased risk for the disease, including:
  
  
• • Adolescents entering high school
    
    
  • College students living in dormitories and residence halls
    
    
  • Microbiologists routinely exposed to meningococcal bacteria
    
    
  • United States military recruits
    
    
  • People living in or traveling to areas with high rates of infection (e.g., Africa)
    
    
  • Anyone with a damaged or removed spleen
    
    
  • People with compromised immune systems
    
    
  • Individuals who may have been exposed to meningitis during an outbreak
    
    
• Haemophilus influenzae type b vaccine (Hib). Routinely given to children in the United States. The Hib type b bacteria was, but no longer is, a leading cause of the disease. The vaccine may also be used on adults with certain diseases (e.g., AIDS, sickle cell anemia).
  
  
• Pneumococcal conjugate vaccine (PCV7). Also part of regular immunizations for young children. It may also be used for older children at risk for pneumococcal disease or who have other serious conditions (e.g., chronic lung disease, cancer). PCV7 should be avoided by children who have had a previous allergic reaction to the vaccine.
  
  
• Pneumococcal polysaccharide vaccine (PPV). This vaccine is recommended by the CDC for children with compromised immune systems or certain chronic conditions (e.g., heart disease) and for adults over age 65.
  
  
• Measles, mumps and rubella (MMR) vaccine. In most cases, people born after 1956 and over the age of 18 years should receive the MMR vaccine at least once. Children usually receive two doses of the vaccine, the first at 12 to 15 months of age and the second between the ages of 4 and 6 years. The vaccine has reduced the occurrence of meningitis formerly caused by measles, mumps or rubella.

Avoiding viruses that cause meningitis reduces the risk of contracting the viral form of the disease (e.g., herpes simplex virus, arboviruses). Cooking meat thoroughly will substantially reduce the risk of listeriosis, which may cause meningitis in some cases. Use of insect repellant when outdoors may help prevent exposure to infected mosquitos and ticks.

Washing hands regularly and properly kills germs and reduces the risk of being infected with the bacteria and viruses that can lead to meningitis. All children and family members are urged to wash their hands thoroughly, particularly before eating and after using the bathroom. Avoiding close contact with people who are ill with certain infections and refraining from sharing food, beverages and eating utensils with others can also reduce the risk of exposure to germs.

Preparing questions in advance can help patients and parents have more meaningful discussions with physicians regarding the child’s treatment options. The following questions related to meningitis may be helpful:

1. What signs should I look for that might indicate meningitis in my child?
   
   
2. How serious is my child’s case of meningitis?
   
   
3. Is my child’s meningitis bacterial or viral?
   
   
4. What are my child’s treatment options?
   
   
5. How long will it take for my child to recover?
   
   
6. How likely is my child to have long-term disabilities as a result of this infection?
   
   
7. Should I warn neighbors, school officials or others about my child’s infection?
   
   
8. How common is this form of meningitis?
   
   
9. Should my family take any other precautions now that my child has this illness?
   
   
10. How do I know if my child’s meningitis is gone?
    
    
11. Will over-the-counter medicines help my child?
    
    
12. My child had meningitis as a baby. Will this affect his or her health in the future?