NOTE: All information is intended for your general knowledge
only and is not a substitute for medical advice or treatment for specific
medical conditions.
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Definitions for Medical Terminology
NOTE: All information is intended for your general knowledge
only and is not a substitute for medical advice or treatment for specific
medical conditions.
Acellular vaccine-
- A vaccine containing partial cellular material as opposed to complete cells.
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.
Acute-
- A short-term, intense health effect.
Adjuvant-
- A substance (e.g. aluminum salt) that is added during production to increase
the body's immune response to a vaccine.
Adverse events-
- Undesirable experiences occurring after immunization that may or may not be
related to the vaccine.
Advisory Committee on Immunization Practices (ACIP)-
- A panel of 10 experts who make recommendations on the use of vaccines in the
United States. The panel is advised on current issues by representatives from
the Centers for Disease Control and Prevention, Food and Drug Administration,
National Institutes of Health, American Academy of Pediatrics, American Academy
of Family Physicians, American Medical Association and others. The
recommendations of the ACIP guide immunization practice at the federal, state
and local level.
Allergy-
- A condition in which the body has an exaggerated response to a substance
(e.g. food or drug). Also known as hypersensitivity.
Anaphylaxis-
- An immediate and severe allergic reaction to a substance (e.g. food or
drugs). Symptoms of anaphylaxis include breathing difficulties, loss of
consciousness and a drop in blood pressure. This condition can be fatal and
requires immediate medical attention.
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.
Antitoxin-
- Antibodies capable of destroying microorganisms including viruses and
bacteria.
Arthralgia-
- Joint pain.
Arthritis-
- A medical condition characterized by inflammation of the joints which
results in pain and difficulty moving.
Association-
- The degree to which the occurrence of two variables or events is linked.
Association describes a situation where the likelihood of one event occurring
depends on the presence of another event or variable. However, an association
between two variables does not necessarily imply a cause and effect
relationship. The term association and relationship are often used
interchangeably. See causal and temporal association.
Asymptomatic infection-
- The presence of an infection without symptoms. Also known as inapparent or subclinical infection.
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.
Autism-
- A chronic developmental disorder usually diagnosed between 18 and 30 months
of age. Symptoms include problems with social interaction and communication as
well as repetitive interests and activities. At this time, the cause of autism
is not known although many experts believe it to be a genetically based disorder
that occurs before birth.
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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.
Bacteria -
- Tiny one-celled organisms present throughout the environment that require a
microscope to be seen. While not all bacteria are harmful, some cause disease.
Examples of bacterial disease include diphtheria, pertussis, tetanus, Haemophilus influenzae and pneumococcus
(pneumonia).
Bias-
- Flaws in the collection, analysis or interpretation of research data that
lead to incorrect conclusions.
Biological plausibility-
- A causal association (or relationship between two factors) is consistent
with existing medical knowledge.
Bone marrow-
- Soft tissue located within bones that produce all blood cells, including the
ones that fight infection.
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.
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- Causal association-
- The presence or absence of a variable (e.g. smoking) is responsible for an
increase or decrease in another variable (e.g. cancer). A change in exposure
leads to a change in the outcome of interest.
Chronic health condition-
- A health related state that lasts for a long period of time (e.g. cancer,
asthma).
Combination vaccine-
- Two or more vaccines administered at once in order to reduce the number of
shots given. For example, the MMR (measles,
mumps, rubella) vaccine.
Communicable-
- Capable of spreading disease. Also known as infectious.
Community immunity-
- Having a large percentage of the population vaccinated in order to prevent
the spread of certain infectious diseases. 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.
Complement- A complex series of blood proteins whose
action "complements" the work of antibodies. Complement destroys antibody-coated
cells, produces inflammation, and regulates immune response.
Conjugate vaccine-
- The joining together of two compounds (usually a protein and polysaccharide)
to increase a vaccine's effectiveness.
Conjunctivitis-
- Inflammation of the mucous membranes surrounding the eye causing the area to
become red and irritated. The membranes may be irritated because of exposure to
heat, cold or chemicals. This condition is also caused by viruses, bacteria or
allergies.
Contraindication-
- A condition in a recipient which is likely to result in a life-threatening
problem if a vaccine were given.
Convulsion-
- See Seizure.
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- Demyelinating disorders-
- A medical condition where the myelin sheath is damaged. The myelin sheath
surrounds nerves and is responsible for the transmission of impulses to the
brain. Damage to the myelin sheath results in muscle weakness, poor
coordination and possible paralysis. Examples of demyelinating disorders
include Multiple Sclerosis (MS), optic neuritis, transverse neuritis and Guillain-Barre Syndrome (GBS).
Diabetes-
- A chronic health condition where the body is unable to produce insulin and
properly breakdown sugar (glucose) in the blood. Symptoms include hunger,
thirst, excessive urination, dehydration and weight loss. The treatment of
diabetes requires daily insulin injections, proper nutrition and regular
exercise. Complications can include heart disease, stroke, neuropathy, poor
circulation leading to loss of limbs, hearing impairment, vision problems and
death.
Disease-
- Sickness, illness or loss of health.
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- Efficacy rate-
- A measure used to describe how good a vaccine is at preventing disease.
Encephalitis-
- Inflammation of the brain caused by a virus. Encephalitis can result in
permanent brain damage or death.
Encephalopathy-
- A general term describing brain dysfunction. Examples include encephalitis,
meningitis, seizures and head trauma.
Epidemic-
- The occurrence of disease within a specific geographical area or population
that is in excess of what is normally expected.
Endemic-
- The continual, low-level presence of disease in a community.
Erythema Multiforme-
- A medical condition characterized by inflammation of the skin or mucous
membranes (including the mouth, throat and eyes). Erthema Multiforme has been
reported following infection. Symptoms persist anywhere from 2 days to 4 weeks
and include skin lesions, blisters, itching, fatigue, joint pain and fever.
Etiology-
- The cause of.
Exposure-
- Contact with infectious agents (bacteria or viruses) in a manner that
promotes transmission and increases the likelihood of disease.
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- Febrile-
- Relating to fever; feverish.
Guillain-Barre Syndrome (GBS)-
- A rare neurological disease characterized by loss of reflexes and temporary
paralysis. Symptoms include weakness, numbness, tingling and increased
sensitivity that spreads over the body. Muscle paralysis starts in the feet and
legs and moves upwards to the arms and hands. Sometimes paralysis can result in
the respiratory muscles causing breathing difficulties. Symptoms usually appear
over the course of one day and may continue to progress for 3 or 4 days up to 3
or 4 weeks. Recovery begins within 2-4 weeks after the progression stops. While
most patients recover, approximately 15%-20% experience persistent symptoms. GBS
is fatal in 5% of cases.
HBsAg-
- Hepatitis B surface antigen.
Herd immunity-
- See community immunity.
Herpes Zoster-
- A disease characterized by painful skin lesions that occur mainly on the
trunk (back and stomach) of the body but which can also develop on the face and
in the mouth. Complications include headache, vomiting, fever and meningitis.
Recovery may take up to 5 weeks. Herpes Zoster is caused by the same virus that
is responsible for chickenpox. Most people are exposed to this virus during
childhood. After the primary infection (chickenpox), the virus becomes dormant,
or inactivated. In some people the virus reactivates years, or even decades,
later and causes herpes zoster. Also known as the shingles.
Hives-
- The eruption of red marks on the skin that are usually accompanied by
itching. This condition can be caused by an allergy (e.g. to food or drugs),
stress, infection or physical agents (e.g. heat or cold). Also known as uticaria.
Hypersensitivity-
- A condition in which the body has an exaggerated response to a substance
(e.g. food or drug). Also known as an allergy.
Hyposensitivity-
- A condition in which the body has a weakened or delayed reaction to a
substance.
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- Immune globulin-
- A protein found in the blood that fights infection. Also known as gamma
globulin.
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 defense against them. This defense 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.
Immunosupression-
- When the immune system is unable to protect the body from disease. This
condition can be caused by disease (like HIV infection or cancer) or by certain
drugs (like those used in chemotherapy). Individuals whose immune systems are
compromised should not receive live, attenuated vaccines.
Inactive vaccine-
- A vaccine made from viruses and bacteria that have been killed through
physical or chemical processes. These killed organisms cannot cause disease.
Inapparent infection-
- The presence of infection without symptoms. Also known as subclinical or asymptomatic
infection.
Incidence-
- The number of new disease cases reported in a population over a certain
period of time.
Incubation period-
- The time from contact with infectious agents (bacteria or viruses) to onset
of disease.
Infectious-
- Capable of spreading disease. Also known as communicable.
Infectious agents-
- Organisms capable of spreading disease (e.g. bacteria or viruses).
Inflammation-
- Redness, swelling, heat and pain resulting from injury to tissue (parts of
the body underneath the skin). Also known as swelling.
Inflammatory Bowel Disease (IBD)-
- A general term for any disease characterized by inflammation of the
bowel. Examples include colitis and Crohn's disease. Symptoms include abdominal
pain, diarrhea, fever, loss of appetite and weight loss.
Investigational vaccine-
- A vaccine that has been approved by the Food and Drug Administration (FDA)
for use in clinical trials on humans. However, investigational vaccines are
still in the testing and evaluation phase and are not licensed for use in the
general public.
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- Jaundice-
- Yellowing of the eyes and skin. This condition is often a symptom of
hepatitis infection.
Live 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 an attenuated vaccine.
Lock Jaw-
- See Tetanus.
Lyme disease-
- A bacterial disease transmitted by infected ticks. Human beings may come
into contact with infected ticks during outdoor activities (camping, hiking).
Symptoms include fatigue, chills, fever, headache, joint and muscle pain,
swollen lymph nodes and a skin rash (in a circular pattern). Long-term problems
include arthritis, nervous system abnormalities, irregular heart rhythm and
meningitis. Lyme disease can be treated with antibiotics or prevented with the
use of a vaccine recently licensed by the Food and Drug Administration.
Lymph-
- A transparent, slightly yellow fluid that carries lymphocytes, bathes the
body tissues, and drains into the lymphatic vessels.
Lymph Nodes-
- Small bean-shaped organs of the immune system, distributed widely throughout
the body and linked by lymphatic vessels. Lymph nodes are gathering sites of B,
T, and other immune cells.
Lymphatic Vessels-
- A bodywide network of channels, similar to blood vessels, that transport
lymph to the immune organs and into the bloodstream.
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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- Macrophage-
- A large cell that helps the body defend itself against disease by
surrounding and destroying foreign organisms (viruses or bacteria).
Memory Cell-
- A group of cells that help the body defend itself against disease by
remembering prior exposure to specific organisms (e.g. viruses or bacteria).
Therefore these cells are able to respond quickly when these organisms
repeatedly threaten the body.
Meningitis-
- Inflammation of the brain and spinal cord that can result in permanent brain
damage and death.
Microbes-
- Tiny organisms (including viruses and bacteria) that can only be seen with a
microscope.
Mucosal membranes-
- The soft, wet tissue that lines body openings specifically the mouth, nose,
rectum and vagina.
Multiple Sclerosis-
- Multiple sclerosis is a disease of the central nervous system characterized
by the destruction of the myelin sheath surrounding neurons, resulting in the
formation of "plaques." MS is a progressive and usually fluctuating disease with
exacerbations (patients feeling worse) and remissions (patients feeling better)
over many decades. Eventually, in most patients, remissions do not reach
baseline levels and permanent disability and sometimes death occurs. The cause
of MS is unknown. The most widely held hypothesis is that MS occurs in patients
with a genetic susceptibility and that some environmental factors "trigger"
exacerbations. MS is 3 times more common in women than men, with diagnosis
usually made as young adults. Also see demyelinating
disorders.
Neuritis-
- Inflammation of the nerves.
Neuropathy-
- A general term for any dysfunction in the peripheral nervous system.
Symptoms include pain, muscle weakness, numbness, loss of coordination and
paralysis. This condition may result in permanent disability.
Optic neuritis-
- A medical condition where vision deteriorates rapidly over hours or days.
One or both eyes may be affected. This condition results for the demyelination
of optic nerves. In most cases, the cause of optic neuritis is unknown.
Patients may regain their vision or be left with permanent impairment. Also see
demyelinating disorders.
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- Orchitis-
- A complication of mumps infection occurring in males (who are beyond
puberty). Symptoms begin 7-10 days after onset of mumps and include
inflammation of the testicles, headache, nausea, vomiting, pain and fever.
Most patients recover but in rare cases sterility occurs.
Otitis Media-
- Inflammation of the middle ear caused by a viral or bacterial infection.
This condition usually occurs along with an upper respiratory infection.
Symptoms include earache, high fever, nausea, vomiting and diarrhea. In
addition, hearing loss, facial paralysis and meningitis may result.
Outbreak-
- Sudden appearance of a disease in a specific geographic area (e.g.
neighborhood or community) or population (e.g. adolescents).
Pandemic-
- An epidemic occurring over a very large 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.
Pathogens-
- Organisms (e.g. bacteria, viruses, parasites and fungi) that cause disease
in human beings.
Phagocyte-
- An immune cell that is able to ingest and destroy microbes and other foreign
matter.
Placebo-
- A substance or treatment that has no effect on human beings.
Pneumonia-
- Inflammation of the lungs characterized by fever, chills, muscle stiffness,
chest pain, cough, shortness of breath, rapid heart rate and difficulty
breathing.
Polysaccharide vaccines-
- Vaccines that are composed of long chains of sugar molecules that resemble
the surface of certain types of bacteria. Polysaccharide vaccines are available
for pneumococcal disease, meningococcal disease and Haemophilus Influenzae type b.
Potency-
- A measure of strength.
Precaution-
- A condition in a recipient which may result in a life-threatening problem if
the vaccine is given, or a condition which could compromise the ability of the
vaccine to produce immunity.
Prevalence-
- The number of disease cases (new and existing) within a population over a
given time period.
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- 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.
Reye Syndrome-
- Encephalopathy (general brain disorder) in children following an acute
illness such as influenza or chickenpox. Symptoms include vomiting, agitation
and lethargy. This condition may result in coma or death.
Residual Seizure Disorder (RSD)-
- See Seizure.
Risk-
- The likelihood that an individual will experience a certain event.
Rotavirus-
- A group of viruses that cause diarrhea in children.
Rubeola-
- Measles.
Seizure-
- The sudden onset of a jerking and staring spell usually caused by fever.
Also known as convulsions.
Shingles-
- See herpes zoster.
Side Effect-
- Undesirable reaction resulting from immunization.
Strain-
- A specific version of an organism. Many diseases, including HIV/AIDS and
hepatitis, have multiple strains.
Subclinical infection-
- The presence of infection without symptoms. Also known as inapparent or asymptomatic infection.
Susceptible-
- Unprotected against disease.
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- Temporal association-
- Two or more events that occur around the same time but are unrelated, chance
occurrences.
Titer-
- The detection of antibodies in blood through a laboratory test.
Transverse Myelitis-
- The sudden onset of spinal cord disease. Symptoms include general back pain
followed by weakness in the feet and legs that moves upward. There is no cure
and many patients are left with permanent disabilities or paralysis. Transverse
Myelitis is a demyelinating disorder that may be associated with Multiple Sclerosis (MS). Also see demyelinating disorders.
Uticaria-
- The eruption of red marks on the skin that are usually accompanied by
itching. This condition can be caused by an allergy (e.g. to food or drugs),
stress, infection or physical agents (e.g. heat or cold). Also known as hives.
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.
Vaccine Adverse Event Reporting System (VAERS)-
- A database managed by the Centers for Disease Control and Prevention and the
Food and Drug Administration. VAERS provides a mechanism for the collection and
analysis of adverse events associated with vaccines currently licensed in the
United States. Reports to VAERS can be made by the vaccine manufacturer,
recipient, their parent/guardian or health care provider. See also CDC VAERS Webpage.
Vaccine Safety Datalink Project (VSD)-
- In order to increase knowledge about vaccine adverse events, the Centers for
Disease Control and Prevention have formed partnerships with four large health
Management Organizations (HMOs) to continually evaluate vaccine safety. The
project contains data on more than 6 million people. Medical records are
monitored for potential adverse events following immunization. The VSD project
allows for planned vaccine safety studies as well as timely investigations of
hypothesis.
Varicella-
- See Chickenpox.
Virus-
- A tiny organism that multiples 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.
Whooping Cough-
- See Pertussis.
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