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What is meningitis?

Meningitis is an infection of the membranes that surround the brain and spinal cord, called the meninges. Meningitis often appears with flu-like symptoms that develop over one to two days. Most cases of meningitis in the U.S. are caused by a viral infection, but it can also be caused by bacteria, parasites, and fungi.

The signs of meningitis may include:

  • Sudden fever
  • Severe headache
  • Nausea or vomiting
  • Double vision
  • Sensitivity to bright light
  • Stiffness in the neck

Distinctive rashes are typically seen in some forms of the disease. Bacterial meningitis may be associated with kidney and adrenal gland failure and shock. Important signs to watch for in an infant include fever, lethargy, not waking for feedings, vomiting, body stiffness, unexplained/unusual irritability, and a full or bulging fontanel (the soft spot on the top of the head).

Some cases of meningitis improve on their own without treatment. Others require emergency treatment with antibiotics and can cause death. Because the disease can occur suddenly and progress rapidly, anyone who is suspected of having meningitis should immediately contact a doctor or go to the hospital.

Types of meningitis

There are multiple kinds of meningitis, categorized by the cause of the infection or inflammation in the meninges.

Bacterial Meningitis

Bacterial meningitis is a rare but potentially fatal disease. Several types of bacteria can first cause an upper respiratory tract infection and then travel through the bloodstream to the brain. The disease can also occur when bacteria invade the meninges directly, rather than traveling from elsewhere in the body. Bacterial meningitis can cause stroke, hearing loss, and permanent brain damage. Types of bacterial meningitis include:

  • Pneumococcal meningitis is the most common and serious form of bacterial meningitis. It is caused by the bacteria Streptococcus pneumoniae, which also causes pneumonia, blood poisoning (septicemia), and ear and sinus infections. Pneumococcal meningitis is particularly dangerous for  children under age 2 and adults with a weakened immune system. People who have had pneumococcal meningitis often suffer neurological damage, which can range from deafness to severe brain damage. Vaccinations are available for some strains of the pneumococcal bacteria.
  • Meningococcal meningitis is very contagious. It is caused by the bacteria Neisseria meningitidis. High-risk groups include infants, people with suppressed immune systems, travelers to foreign countries where the disease is common, and people who live in dormitories or barracks, including college students (freshmen in particular) and military recruits. Between 10-15% of cases of meningococcal meningitis are fatal and another 10-15% cause brain damage and other serious side effects.  People in close contact with a person diagnosed with meningococcal meningitis should be given preventative antibiotics.

Other forms of bacterial meningitis include:

  • Listeria monocytogenes meningitis, which can sometimes spread through foods such as unpasteurized dairy or deli meats, and is most common in older adults, newborns, and immunocompromised people.
  • E.coli meningitis, which is more common in older adults, newborns, and individuals with implanted brain devices or who have had brain surgery. It may be transmitted from the parent to a baby through the birth canal.
  • Mycobacterium tuberculosis meningitis, a rare disease that occurs when the bacteria that causes tuberculosis attacks the meninges.

Haemophilus influenzae meningitis was at one time the most common form of bacterial meningitis. Fortunately, the HIB (haemophilus influenzae b) vaccine has greatly reduced the number of cases in the United States. Those most at risk of getting this disease are children in child-care settings and children who do not have access to the vaccine.

Viral Meningitis

Viral meningitis is usually caused by enteroviruses. Enteroviruses are common viruses that usually enter the body through the mouth and nose. Enteroviruses are present in mucus, saliva, and feces, and can be transmitted through direct contact with an infected person or through contact with an infected object or surface. Other viruses that can cause meningitis include varicella zoster (the virus that causes chicken pox and shingles), influenza, mumps, HIV, and genital herpes.

Fungal Meningitis

Fungal infections can also cause meningitis. The most common form of fungal meningitis is caused by a fungus found in bird droppings and dirt known as Cryptococcus neoformans. Meningitis caused by this fungus (cyptococcal meningitis) mostly occurs in immunocompromised people but can also occur in healthy people. It can be slow to develop and live in the body for weeks before it shows symptoms. Although treatable, fungal meningitis often recurs in nearly half of affected persons.

Parasites that cause meningitis are more common outside of the U.S. and include cysticercosis (a tapeworm infection in the brain) and cerebral malaria. There are rare cases of meningitis caused by amoebas (single cell organisms), sometimes related to freshwater swimming. These can be rapidly fatal.

Who is more likely to get meningitis?

Anyone can get meningitis. People with weakened immune systems, including people living with HIV/AIDS and those taking medications that suppress the activation of the immune system, are at increased risk.

Some forms of bacterial meningitis are contagious and can spread through contact with:

  • Saliva
  • Nasal discharge
  • Feces
  • Kissing, coughing, or sharing drinking glasses, eating utensils, or personal items such as toothbrushes

People sharing a household, at a day care center, or in a classroom with an infected person can become infected. Any children who have not received routine vaccines are at increased risk of developing certain types of bacterial meningitis. Additional risk factors include recent travel and environmental exposure (such as being exposed to a parasite or bitten by an insect).

Not all meningitis is caused by infections. Non-infectious causes include autoimmune/rheumatological diseases and certain medications.


Preventing meningitis

People should avoid sharing food, utensils, glasses, and other objects with someone who may be exposed to or have meningitis. All people should wash their hands often with soap and water. Communal living areas like dormitories and barracks should be cleaned and sanitized regularly to avoid the spread of infections.

Effective vaccines are available to prevent Haemophilus influenza, pneumococcal meningitis, and meningococcal meningitis.

People who live, work, or go to school with a person who has been diagnosed with bacterial meningitis may prescribed antibiotics for a few days as a preventive measure.

To lessen the risk of being bitten by an infected mosquito or insect, people should:

  • Limit outdoor activities at night
  • Wear pants and long-sleeved clothing when outdoors
  • Use insect repellents that are most effective for that particular region
  • Try to stay away from outdoor areas near free-standing pools of water where mosquitoes and other insects breed

How is meningitis diagnosed and treated?

Diagnosing meningitis

Early diagnosis of meningitis can make a big difference in a person’s recovery or survival. Symptoms can appear suddenly and escalate to brain damage, hearing and/or vision loss, and even death. If a person is suspected of having meningitis, the healthcare provider will ask about activities conducted over the past several days or weeks, including travel, exposure to insects, contact with sick people, etc. The doctor will also perform a physical exam and review the person’s medical history to identify preexisting medical conditions and medications. Doctors may use various diagnostic tests to confirm the presence of infection or inflammation in the meninges. 

Diagnostic tests for meningitis may include the following:

  • A neurological examination, which involves a series of tests designed to assess movement and sensory function, nerve function, hearing and speech, vision, coordination and balance, mental status, and changes in mood or behavior.
  • Labs of blood, urine, and body secretions, which can help detect and identify an infection in the brain or spinal cord and determine the presence of antibodies and foreign proteins. These tests can also rule out conditions that may have similar symptoms.
  • Analysis of the cerebrospinal fluid that surrounds and protects the brain and spinal cord, which can detect infections, acute and chronic inflammation, and other diseases. Cerebrospinal fluid is obtained through a procedure called a lumbar puncture.

Brain imaging can reveal signs of inflammation, bleeding, or other abnormalities. A CT (computed tomography) or MRI (magnetic resonance imaging) scan can aid in diagnosing meningitis.

Treating meningitis

People who are suspected of having meningitis should receive immediate, aggressive medical treatment. The disease can progress quickly and has the potential to cause severe, irreversible neurological damage.

Early treatment of bacterial meningitis involves antibiotics that can cross the blood-brain barrier. These antibiotics can greatly reduce the risk of dying from the disease. A doctor may also prescribe anticonvulsant medications to prevent seizures and corticosteroids (such as prednisone) to reduce brain inflammation, relieve pressure and swelling, and prevent hearing loss.

Antibiotics, developed to kill bacteria, are not effective against viruses. Fortunately, viral meningitis is rarely life threatening and no specific treatment is needed. Fungal meningitis is treated with intravenous antifungal medications.

The outlook for individuals with meningitis generally depends on the type of meningitis, the severity of the illness, and how quickly treatment is given. In most cases, people with very mild meningitis can make a full recovery, although the process may be slow.

Individuals who experience only headache, fever, and stiff neck may recover in two to four weeks. Individuals with bacterial meningitis typically show some relief 48-72 hours following initial treatment but are more likely to experience complications of the disease. In more serious cases, the meningitis can cause hearing and/or speech loss, blindness, permanent brain and nerve damage, behavioral changes, cognitive disabilities, lack of muscle control, seizures, and memory loss. These individuals may need long-term therapy, medication, and supportive care. 


What are the latest updates on meningitis?

NINDS, a component of the National Institutes of Health (NIH), the leading supporter of biomedical research in the world, is the primary federal funding agency on meningitis and other neurological disorders. The National Institute of Allergy and Infectious Diseases (NIAID) also conducts and funds research on meningitis. Thanks to scientific research, vaccines are now available for several types of meningitis.

NINDS’s research has contributed to our understanding of meningitis and how the infection can permanently damage the brain’s immune response and change immune cells in the meninges. These changes can make the immune system work less well in fighting off future infections in the meninges and elsewhere in the brain. A deeper understanding of how these infections affect the brain hopefully will eventually help to develop more effective treatments and therapeutics to support recovery after meningitis.

NINDS-funded researchers are currently exploring ways to improve survival in cryptococcal meningitis, seeking to understand the relationships between brain changes seen in tuberculosis meningitis and stroke , and investigating the impact of E. coli in newborns’ microbiomes to hopefully one day identify probiotics to combat long-term colonization of the bacteria.

Current diagnostic tests for some types of meningitis are insufficiently sensitive and may miss positive cases. NINDS-funded researchers are also working identify diagnostic tests for tuberculosis meningitis, which has a mortality rate of over 50%.

For research articles and summaries on meningitis, search PubMed, which contains citations from medical journals and other sites.

Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people with meningitis?

Consider participating in a clinical trial so clinicians and scientists can learn more about meningitis and related disorders. Clinical research with human study participants helps researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of study participants are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with meningitis at

Where can I find more information about meningitis?

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