Glossary

We’ve prepared a Glossary for the course that contains a list of the key terms used throughout the course. You can also download this as a PDF from the download link at the bottom of this page.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Active immunity

The production of antibodies against a specific disease by the immune system. Active immunity can be acquired in two ways, either by contracting the disease or through vaccination. Active immunity is usually permanent, meaning an individual is protected from the disease for the duration of their lives.

Antibody

A protein found in the blood that is produced in response to foreign substances (e.g. bacteria or viruses) invading the body. Antibodies protect the body from disease by binding to these organisms and destroying them.

Antigens

Foreign substances (e.g. bacteria or viruses) in the body that are capable of causing disease. The presence of antigens in the body triggers an immune response, usually the production of antibodies.

Antimicrobial

A chemical substance that kills or inhibits the growth of microorganisms such as bacteria, viruses or fungi. (See also: antibiotic, which is a class of antimicrobials).

Antimicrobial Stewardship

An organisational or healthcare-system-wide approach to promoting and monitoring judicious use of antimicrobials to preserve their future effectiveness.

Antiviral

Literally “against-virus” — any medicine capable of destroying or weakening a virus.

Attenuated vaccine:

A vaccine in which live virus is weakened through chemical or physical processes in order to produce an immune response without causing the severe effects of the disease. Attenuated vaccines currently licensed in the United States include measles, mumps, rubella, polio, yellow fever and varicella. Also known as a live vaccine.


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B

B cells

Small white blood cells that help the body defend itself against infection. These cells are produced in bone marrow and develop into plasma cells which produce antibodies. Also known as B lymphocytes.

Biofilms

An assemblage of surface-associated microbial cells that is enclosed in an extracellular polymeric substance matrix.

Biomarker

Tests that can be used to follow body processes and diseases in humans and animals. They can be used to predict how a patient will respond to a medicine or whether they have, or are likely to develop, a certain disease.

Blood Culture

A Microbiological culture of blood, which usually is a sterile environment. It is employed to detect infections that are spreading through the bloodstream, mainly in patients with sepsis.

Booster shots

Additional doses of a vaccine needed periodically to “boost” the immune system. For example, the tetanus and diphtheria (Td) vaccine which is recommended for adults every ten years.

Breakthrough infection

Development of a disease despite a person’s having responded to a vaccine.


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C

Communicable

That which can be transmitted from one person or animal to another. Also known as infectious.

Community immunity

A situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely. Even individuals not vaccinated (such as newborns and those with chronic illnesses) are offered some protection because the disease has little opportunity to spread within the community. Also known as herd immunity.

Conjugate vaccine

The joining together of two compounds (usually a protein and polysaccharide) to increase a vaccine’s effectiveness.


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E

Efficacy

The extent to which medical interventions achieve health improvements under ideal circumstances.

Embolization

A procedure in which the blood supply to a tumour or an abnormal area of tissue is blocked.

Endemic

The continual, low-level presence of disease in a community

Epidemic

The occurrence of disease within a specific geographical area or population that is in excess of what is normally expected.

Epidemiology

The study of factors that have an impact on disease in the human community. Often used in the control of health problems.


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H

Hepatitis A

A minor viral disease, that usually does not persist in the blood; transmitted through ingestion of contaminated food or water.

Hepatitis B

A viral disease transmitted by infected blood or blood products, or through unprotected sex with someone who is infected.

Hepatitis C

Is a liver disease caused by the Hepatitis C virus (HCV), which is found in the blood of persons who have the disease. HCV is spread by contact with the blood of an infected person.

Hepatitis D

Is a defective virus that needs the hepatitis B virus to exist. Hepatitis D virus (HDV) is found in the blood of persons infected with the virus.

Hepatitis E

Is a virus (HEV) transmitted in much the same way as hepatitis A virus. Hepatitis E, however, does not often occur in the United States.

Herd immunity

See Community immunity.


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I

Immune system

The complex system in the body responsible for fighting disease. Its primary function is to identify foreign substances in the body (bacteria, viruses, fungi or parasites) and develop a defence against them. This defence is known as the immune response. It involves production of protein molecules called antibodies to eliminate foreign organisms that invade the body.

Immunity

Protection against a disease. There are two types of immunity, passive and active. Immunity is indicated by the presence of antibodies in the blood and can usually be determined with a laboratory test. See active and passive immunity.

Immunization

The process by which a person or animal becomes protected against a disease. This term is often used interchangeably with vaccination or inoculation.

Inactivated vaccine

A vaccine made from viruses and bacteria that have been killed through physical or chemical processes. These killed organisms cannot cause disease.

Incidence

The number of new disease cases reported in a population over a certain period of time.

Infection

The invasion and reproduction of pathogenic (disease causing) organisms inside the body. This can cause tissue injury and progress to disease.

Infectivity

The measure of the ability of a pathogen to cause infection.

Infection Control

Infection control prevents or stops the spread of infections in healthcare settings.

Inflammatory Response

The body’s reaction to many infections, mediated by the immune system.


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L

Live vaccine

A vaccine in which live virus is weakened (attenuated) through chemical or physical processes in order to produce an immune response without causing the severe effects of the disease. Attenuated vaccines currently licensed in the United States include measles, mumps, rubella, shingles (herpes zoster), varicella, and yellow fever. Also known as an attenuated vaccine.

Lymphocytes

Small white blood cells that help the body defend itself against infection. These cells are produced in bone marrow and develop into plasma cells which produce antibodies. Also known as B cells.


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M

Measles

A contagious viral disease marked by the eruption of red circular spots on the skin.

Microscopy

Use of a microscope.


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N

Neutrpenia

Neutropenia is a condition in which the number of neutrophils (a type of white blood cell) in the bloodstream is decreased, affecting the body’s ability to fight off infections. Neutropenia is defined as an absolute neutrophil count (ANC) of less than 1500 per microliter (1500/microL); severe neutropenia is defined as an ANC of less than 500/microL.


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O

Opportunistic Pathogens

An infectious microorganism that is normally a commensal or does not harm its host but can cause disease when the host’s resistance is low, for example due to a weakened immune system.


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P

Pandemic

An epidemic occurring over a very large geographic area.

Passive immunity

Protection against disease through antibodies produced by another human being or animal. Passive immunity is effective, but protection is generally limited and diminishes over time (usually a few weeks or months). For example, maternal antibodies are passed to the infant prior to birth. These antibodies temporarily protect the baby for the first 4-6 months of life.

Pathogen

A disease causing microorganism.

Pathogenicity

The ability of a pathogen to cause disease.

Potency

A measure of strength.

Prevalence

The number of disease cases (new and existing) within a population over a given time period.


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Q

Quarantine

The isolation of a person or animal who has a disease (or is suspected of having a disease) in order to prevent further spread of the disease.


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R

Resistance

A property of some bacteria which renders certain antibiotics ineffective against them in the laboratory or when they are used to treat infections. Resistance may be an intrinsic characteristic or may be acquired and selected by exposure to antibiotics. The latter category frequently has greater public health significance.


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S

Smallpox

An acute, highly infectious, often fatal disease caused by a poxvirus and characterized by high fever and aches with subsequent widespread eruption of pimples that blister, produce pus, and form pockmarks. Also called variola.

Strain

A population of cells of a single species all descended from a single cell: a clone

Superficial

On the surface or shallow. Skin infections are described as superficial infections.

Surveillance

Surveillance of antimicrobial resistance is the tracking of changes in microbial populations.

Systemic Infections

An infection which has spread to multiple parts of the body.

Systematic Review

A review in which evidence from scientific studies has been identified, appraised and synthesised in a methodical way according to predetermined criteria. The review may include a meta-analysis.


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V

Vaccination

Injection of a killed or weakened infectious organism in order to prevent the disease.

Vaccine

A product that produces immunity therefore protecting the body from the disease. Vaccines are administered through needle injections, by mouth and by aerosol.

Virulence

The relative capacity of a pathogen to overcome body defences.

Virus

A tiny organism that multiplies within cells and causes disease such as chickenpox, measles, mumps, rubella, pertussis and hepatitis. Viruses are not affected by antibiotics, the drugs used to kill bacteria.


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W


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X


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Y


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Z


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This article is from the free online course:

The Role of Vaccines in Preventing Infectious Diseases and Antimicrobial Resistance

BSAC