Meningitis is an infection of the membranes covering the brain and spinal cord. This covering is called the meninges.

Meningitis - bacterial; Meningitis - viral; Meningitis - fungal; Meningitis - vaccine

The most common causes of meningitis are viral infections. These infections usually get better without treatment. Bacterial meningitis infections, however, are very serious. They may result in death or brain damage, even if treated. A lumbar puncture (or spinal tap) is required to determine the specific cause.

Meningitis may also be caused by:

• Chemical irritation
• Medicine allergies
• Fungi
• Parasites
• Tumors

Many types of viruses can cause meningitis:

• Enteroviruses: These are viruses that also can cause intestinal illness.
• Herpes viruses: These are the same viruses that can cause cold sores and genital herpes. However, people with cold sores or genital herpes do not have a higher chance of developing herpes meningitis.
• HIV: This virus can cause meningitis during the early stages of HIV infection.
• Mumps virus: This virus causes a contagious disease that leads to painful swelling of the salivary glands. Meningitis is a complication of a mumps infection.
• West Nile virus: This virus is spread by mosquito bites and is an important cause of viral meningitis in most of the United States.

Enteroviral meningitis occurs more often than bacterial meningitis and is milder. It usually occurs in the late summer and early fall. It most often affects children and adults under age 30. Symptoms may include:

• Headache
• Sensitivity to light (photophobia)
• Slight fever
• Upset stomach and diarrhea
• Fatigue

Bacterial meningitis is an emergency. You will need immediate treatment in a hospital. Symptoms usually come on quickly, and may include:

• Fever and chills
• Mental status changes
• Nausea and vomiting
• Sensitivity to light
• Severe headache
• Stiff neck

Other symptoms that can occur with this disease:

• Agitation
• Bulging fontanelles in babies
• Decreased alertness
• Poor feeding or irritability in children
• Rapid breathing
• Unusual posture, with the head and neck arched backward (opisthotonos)

You cannot tell if you have bacterial or viral meningitis by how you feel. Your health care provider must find out the cause. Go to a hospital emergency department right away if you think you have symptoms of meningitis.

Antibiotics are used to treat bacterial meningitis. Antibiotics do not treat viral meningitis. However, antiviral medicine may be given to those with herpes meningitis.

Other treatments will include:

• Fluids through a vein (intravenous)
• Medicines to treat symptoms, such as brain swelling, shock, and seizures

Early diagnosis and treatment of bacterial meningitis is essential to prevent permanent neurological damage. Viral meningitis is usually not serious, and symptoms should disappear within 2 weeks with no lasting complications.

Without prompt treatment, meningitis may result in the following:

• Brain or neurologic damage
• Buildup of fluid between the skull and brain (subdural effusion)
• Hearing loss
• Buildup of fluid inside the skull that leads to brain swelling (hydrocephalus)
• Seizures
• Death

If you think that you or your child has symptoms of meningitis, get emergency medical help immediately. Early treatment is key to a good outcome.

Certain vaccines can help prevent some types of bacterial meningitis:

• Haemophilus vaccine (HiB vaccine) is given to children.
• Pneumococcal vaccine is given to children and adults.
• Meningococcal vaccine is given to children and adults; some communities hold vaccination campaigns after an outbreak of meningococcal meningitis.

Household members and others in close contact with people who have meningococcal meningitis should receive antibiotics to prevent becoming infected.

Published Date: November 10, 2024
Published By: Jatin M. Vyas, MD, PhD, Roy and Diana Vagelos Professor in Medicine, Columbia University Vagelos College of Physicians and Surgeons, Division of Infectious Diseases, Department of Medicine, New York, NY. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Hasbun R, Van de Beek D, Brouwer MC, Tunkel AR. Acute meningitis. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 87.

Nath A. Meningitis: bacterial, viral, and other. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 381.