Glossary

AIDS (Acquired Immune Deficiency Syndrome): syndrome occurring from the effects of the human immunodeficiency virus (HIV), in which the capacity of the immune system to deal with infections is diminished

Amoeba: (Plural: amoebae) unicellular organism in the genus protozoa

Antibiotic: class of antimicrobials used to treat infections caused by bacteria and other microorganisms

Antigen: molecule that stimulates an immune response

Bacterium: (Plural: bacteria) unicellular microorganism that is able to multiply by itself (compare to virus).  Bacteria are found all over the body and may be present without causing disease

Basilar skull fracture: linear skull fracture involving the base of the skull

Capsular polysaccharide: capsule comprised of polysaccharide that covers the surface of certain bacteria.  Capsules are very important virulence factors of many bacteria

Carrier: an individual who has potentially disease-causing bacteria living in the nasopharynx but who do not suffer any ill-effects associated with the presence of these bacteria

Cerebrospinal fluid (CSF): clear fluid that occupies the subarachnoid space in the brain.  CSF is normally sterile

Chemoprophylaxis: administration of a drug in order to prevent, rather than to treat, a disease

Conjugate vaccine: vaccine in which an antigen that induces a poor immune response is coupled to a carrier protein that induces a strong immune response, resulting in a strong and persistent immune response to both antigens

Encephalitis: acute inflammation of the brain

Endemic: population in which a low level of infection is maintained

Epidemic: a disease that appears in a population and results in a larger number of cases than would normally be expected

Epidemiology: the study of factors affecting the health and illness of populations and the spread of disease within a population

Fontanelle: the soft spot on a newborn baby’s skull where the cartilage has not yet hardened to bone

Fungus: (Plural: fungi) microorganism that is able to cause infection and that obtains energy sources by either feeding on dead matter or by invading other cells

Gram stain: method of staining bacteria so they can be identified under the light microscope

Haemophilus influenzae: bacterium that causes Hib meningitis.  H. influenzae used to be a major cause of bacterial meningitis but the number of cases has fallen dramatically since the introduction of routine vaccination against Hib disease

Haemorrhagic rash: a sign of septicaemia caused by blood leaking into vessels under the skin.  It is characterised by a rash that does not fade under pressure and may be identified using the tumbler test

Hib disease: any disease caused by Haemophilus influenzae type b

Hib meningitis: meningitis caused by Haemophilus influenzae type b

Hib vaccine: vaccine that provides protection against Haemophilus influenzae type b infections

Hypoglycorrhachia: abnormally low concentration of glucose in the cerebrospinal fluid

Immunocompromised: impaired immune system caused by disease or treatment (e.g. AIDS patients or those receiving immunosuppressive therapy), meaning patients are more susceptible to infection

Immunodeficient: impaired immune system caused by a disorder (e.g. leukaemia patients), meaning that patients are more susceptible to infection

Immunogenicity: the ability of an antigen or vaccine to stimulate an immune response

Immunosuppressed: impaired immune system.  Immunosuppressed patients are more susceptible to infection than people with healthy immune systems

Meningitis C (MenC) vaccine: polysaccharide vaccine against Neisseria meningitidis serogroup C

Meningitis C conjugate (MenCC) vaccine: polysaccharide conjugate vaccine against Neisseria meningitidis serogroup C

Meninges: a system of membranes that surround the brain and spine

Meningitis: inflammation of the meninges

Meningitis belt: a sub-Saharan region of Africa stretching from Senegal to Ethiopia in which the highest burden of meningococcal serogroup A disease occurs and where epidemics of meningitis are frequent

Meningococcal disease: any disease caused by N. meningitidis

Meningococcal meningitis: meningitis caused by N. meningitidis

Meningococcus: alternative name for N. meningitidis

Nasopharynx: the nasal part of the pharynx that lies behind the nose and above the level of the soft palate

Neisseria meningitidis: bacterium which is responsible for causing a large proportion of bacterial meningitis.  There are at least thirteen different serogroups of N. meningitidis, however only five of the identified serogroups (A, B, C, Y and W135) usually show pathogenic potential.

Neonate: new born baby, especially one less than 4 weeks old

Pleocytosis: the presence of a greater number of cells than would be expected in a healthy individual

Pneumococcal conjugate vaccine (PCV): vaccine that provides protection against Streptococcus pneumoniae infections

Pneumococcal disease: any disease caused by S. pneumoniae

Pneumococcal meningitis: meningitis caused by S. pneumoniae

Pneumococcus: alternative name for S. pneumoniae

Polysaccharide vaccine: vaccines in which the bacterial antigen is purified capsular polysaccharides

Septicaemia: blood poisoning that occurs when bacteria enter the blood stream, multiply rapidly and release toxins

Sequela: (Plural: sequelae) a pathological condition resulting from a disease

Serogroup: a group of the same species differentiated from other groups of the same species by differences in antigenicity

Sterile: free from bacteria, viruses and other microorganisms

Streptococcus pneumoniae: bacterium capable of causing meningitis. There are over 90 serogroups of S. pneumoniae, but only a small proportion of these cause disease

Subarachnoid space: the space between the arachnoid and pia layers of the meninges found between the skull and the cerebral cortex

Tinnitus: a sound, such as ringing or buzzing, in one or two ears occurring without external stimulus and caused by a specific condition

Virus: a microorganism that cannot multiply by itself so invades cells in order to proliferate (compare to bacteria)