Meningitis is a complex disease. Here are some terms that can help clear things up…

Antibiotic: A substance produced from a microorganism that, in small amounts, can deter or kill another germ. When nontoxic, antibiotics are used to treat infectious diseases.

Bacteria: Single-celled germs that typically live in soil, water, or the bodies of plants and animals. They can cause chemical effects in the body and disease.

Bacterial meningitis: Swelling of the meninges, which are the covering of the brain, caused by bacteria. It can be serious and life threatening.

Carrier: A person who carries the germs of a disease. Carriers may not show any symptoms but can pass these germs to others.

Chemotherapy: Specific chemicals that can help control an illness.

Corticosteroids: Compounds that are produced by the outer part of the adrenal gland and used to calm inflammation.

CT (computed tomography) scan: A computerized image of a body structure. This is done through a series of cross-sectional images made along an axis.

Encephalitis: Swelling of the brain.

Enterovirus: A type of virus that usually lives in the intestinal tract. The infection is often mild but can lead to other diseases.

Epidemic: A sudden outbreak of a disease, occurring in higher numbers than expected.

Hand-foot-and-mouth disease (HFMD): A common illness among infants and children. Symptoms often include fever, sores in the mouth, and a rash with blisters. The most common cause is the coxsackievirus. (HFMD should not be confused with foot-and-mouth disease, which primarily affects cattle, sheep, and swine. The 2 diseases are nothing alike.)

Hib (Haemophilus influenzae type b): A type of bacteria that can cause meningitis. The Hib vaccine has reduced the rate of this form of the disease among children in the United States by more than 99%.

IV (intravenous tube): A device used to deliver medicine, blood, or nutrients into a vein.

Leukemia: A severe, life-threatening cancer that involves the blood-forming organs.

Lymphoma: A disorder of the lymphoid tissue, which can be life threatening.

MCV4: This vaccine protects against 4 of the 5 kinds of bacteria that cause most cases of meningococcal meningitis and blood poisoning.

Meninges: The membranes or tissues that surround the brain and spinal cord.

Meningitis: Swelling of the meninges—the covering of the brain and spinal cord—usually caused by bacteria or a virus. If caused by Neisseria meningitidis bacteria, it goes by the name meningococcal disease.

Meningococcal meningitis: Bacterial meningitis caused by the infection Neisseria meningitidis.

MRI (magnetic resonance imaging): Computerized images of internal body tissues. The procedure focuses on atoms within the body through the use of radio waves.

Neisseria meningitidis: A bacteria that lives in the nose and the mouth. It can cause meningitis and pneumonia.

PCV (pneumococcal vaccine): This vaccine protects against pneumococcal disease, a serious bacterial infection that can lead to meningitis.

Pneumonia: Swelling of the lungs, usually caused by infection.

Prophylactic treatment: Medicine that is taken before symptoms are seen. It is a way to prevent disease, and it’s usually given if the patient has been exposed to an infectious disease.

Respiratory infection: An infection related to respiration (breathing). The term upper respiratory infection refers to the common cold. Over 200 different viruses can cause a cold.

Spinal cord: Relays messages to and from the brain. It is housed inside the bone disks that make up the spine (vertebrae).

Spinal tap: Also known as a lumbar puncture, a spinal tap is the insertion of a needle into the fluid within the spinal cord. It is performed to examine the fluid in the spinal cord in order to diagnose a disease (such as bacterial meningitis).

Streptococcus pneumoniae: A bacteria commonly found in the back of the nose of healthy people—of which more than 90 strains have been identified. It can cause several types of diseases, and is the most common cause of bacterial meningitis.

Vertebrae: The 33 small bones that make up the spinal column.

Viral meningitis: The most common type of meningitis, viral meningitis is serious but rarely deadly in people with normal immunity. It usually lasts from 7 to 10 days, with the patient recovering completely.

Virus: A microscopic agent that can cause infection and multiply in living host cells.