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Immunization Dictionary
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We wish to express our appreciation to the Texas Department of Health's Immunization Division for giving their permission to use their Immunization Dictionary.
Definitions for Vaccine-Preventable Diseases (VPDs)
- Diphtheria
- Diphtheria is an acute infectious disease of the nose, throat, respiratory passages or
skin caused by bacteria usually passed, via coughing or sneezing, from one infected person to
the nose or throat of another. Symptoms include the gradual onset of a sore throat, a
low-grade fever, and weakness. A thick mucus membrane often covers the entire throat and
extends to respiratory passages, making it difficult to breathe. The lymph nodes of the neck
tend to be enlarged. Diphtheria can lead to heart failure, paralysis and death.
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- Haemophilus influenzae type b (Hib)
- Hib bacteria reside in the nose and throat of many people without making them ill, but
can cause serious illness, especially in preschool-aged children. Before a vaccine was
available, Hib disease was the most common cause of meningitis in children under the age of
five, and often led to pneumonia, skin infections, hearing loss, permanent brain injury or
death. The disease is spread through the air by coughing and sneezing. Symptoms of illness
include a high fever, severe headache, stiff neck, quiet or withdrawn behavior, sensitivity
to light, vomiting, ear infections and convulsions. Hib infection can also cause
epiglottitis—a swelling in the throat which is potentially life-threatening.
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- Hepatitis A
- Hepatitis A is an infection of the liver caused by the hepatitis A virus. It is spread
from person to person by putting something in the mouth that has been contaminated with the
stool of an infected person. Symptoms include lack of energy, diarrhea, fever, nausea and
jaundice (yellow color to the whites of the eyes or skin). Not all infected people have
symptoms but can still infect others. Many children do not have symptoms, so they often play
a major role in passing the infection to others. The highest rates of hepatitis A are among
children and young adults. Long term effects are uncommon, however there are about 100 deaths
nationally each year from hepatitis A complications.
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- Hepatitis B
- Hepatitis B is a potentially serious infection of the liver that can cause chronic
liver disease and can lead to liver cancer. Symptoms include nausea, vomiting, abdominal pain
and jaundice. However, many people who become infected have no symptoms. A small number of
people infected with hepatitis B will carry the virus for life and can unknowingly spread the
disease to others. The younger a person is when becoming infected, the greater the risk of
chronic infection, chronic liver disease and liver cancer. The disease is spread through
exposure to infected blood and body fluids. Hepatitis B can be spread by sharing toothbrushes,
needles or razors that belong to an infected person; through contact with infected blood such
as health care workers at a health care setting; using equipment that has not been sterilized
for body-piercing or tattooing; having sex with a person who has hepatitis B; or by an
infected mother to her baby during childbirth. A baby born to a mother who has hepatitis B
has a 90 percent chance of getting the disease. Those babies infected have a 90 percent
chance of becoming chronically infected and 25 percent will die of chronic liver disease as
adults. Immunization at birth is important for prevention of the disease.
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- Herpes Zoster (Shingles)
- This disease is 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.
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- Human Papillomavirus (HPV)
- Human papillomavirus (HPV) is the most common sexually transmitted infection in the U.S. and is the leading cause of cervical cancer. In addition to cervical cancer, HPV infection is also associated
with anogenital cancers less common than cervical cancer, such as cancer of the vulva, vagina, penis and anus. The association of genital types of HPV with non-genital cancers is less well established, but studies support a role for these HPV types in a subset of oral cavity and pharyngeal cancers.
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- Measles
- Measles is a potentially serious and highly contagious childhood disease. It can lead
to ear infection, pneumonia, seizures, brain damage and death. Before the measles vaccine was
introduced, measles caused about 400 deaths in the U.S. each year. Measles begins with
cold-like symptoms: fever, red runny eyes, cough, runny nose and tiredness. This lasts about
three days. Then, small white spots appear on the inside of the mouth and a rash begins,
usually on the face. This red, raised rash spreads rapidly over the neck, upper arms and
chest. Later it spreads over the back, abdomen, rest of the arms, thighs, legs and feet. The
illness lasts 7 to 10 days.
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- Meningococcal
- Meningococcal disease is an acute, potentially severe illness caused by the bacterium Neisseria meningitidis. N. meningitidis is a leading cause of bacterial meningitis and sepsis in the U.S. It can also cause other diseases, such as pneumonia and arthritis. The incubation period of meningococcal disease is 3 to 4 days, with a range of 2 to 10 days.
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- Mumps
- Mumps is caused by a virus. It usually causes painful swelling of the glands that lie
just above the back angle of the jaw, but other glands may be affected. It can cause fever,
headache and mild respiratory symptoms. After puberty, mumps can cause swollen testes or
ovaries. Rarely, mumps cause deafness. Mumps is transmitted through the air or by direct
contact with the saliva of an infected person. Many people with a mumps virus infection may
have mild symptoms that may resemble a cold. Symptoms of mumps generally last from one
week to 10 days.
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- Pertussis (Whooping Cough)
- Pertussis is a highly contagious bacterial respiratory infection spread by coughing or
sneezing. It starts like a common cold, but within a few days coughs come in exhausting
bursts, often followed by a "whooping" sound as the person breathes in. Long
coughing spells make it difficult for a person to eat, drink or even breathe. Vomiting can
also follow a long coughing spell. The disease is most serious in small infants. With older
children and adults the disease can be quite mild or can cause several weeks of exhausting
coughing. Whooping cough is transmitted through the air when an infected person coughs.
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- Pneumococcal
- Pneumococcal pneumonia is the most common clinical
presentation of pneumococcal disease among adults,
although pneumonia alone is not considered to be an “invasive” disease. The incubation period of pneumococcal
pneumonia is short, about 1 to 3 days. Symptoms generally include an abrupt onset of fever and chills or rigors.
Typically there is a single shaking chill (rigor), and repeated shaking chills
are uncommon. Other common symptoms include pleuritic
chest pain, productive cough of mucopurulent, rusty
sputum, dyspnea (shortness of breath), tachypnea (rapid
breathing), hypoxia (poor oxygenation), tachycardia (rapid
heart rate), malaise, and weakness. Nausea, vomiting, and
headaches occur less frequently.
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- Polio
- Wild polio virus has been eliminated in North and South America but not elsewhere
in the world, which means all children should continue to be immunized against it. Polio is a
viral infection transmitted by fecal-oral contact. Milder cases may last only a few days,
causing fever, sore throat, stomach ache and headache. If the disease worsens, it can cause
severe muscle pain, paralysis, breathing difficulty, and even death.
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- Rotavirus
- Rotavirus is recognized as the most common cause of severe gastroenteritis in infants and young children in the U.S. It is now known that infection with rotavirus is nearly universal, with almost all children infected by 5 years of age. Rotavirus is responsible for 20–60 deaths per year in the U.S. and up to 500,000 deaths from diarrhea worldwide.
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- Rubella (German Measles)
- Rubella is a relatively mild viral illness that may go undiagnosed because of its mild
symptoms. Although it seldom poses a major risk to children, rubella does put unborn infants
at considerable risk. Pregnant women who get rubella can miscarry or have babies with severe
birth defects. The first symptoms of rubella are usually swollen, tender glands at the back
of the neck and behind the ears, a mild fever and then a rash. The rash and a "flush"
appear first on the face, then spread quickly to the trunk, upper arms and thighs. The rash
then moves to the forearms, hands and feet. Teenagers and adults may have painful or swollen
joints.
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- Tetanus (Lockjaw)
- Tetanus is a severe, often fatal disease. The bacteria that cause tetanus are widely
distributed in soil and are found in the waste of many animals. People who get tetanus suffer
from stiffness and spasms of the muscles. The larynx (throat) can close causing breathing and
eating difficulties, muscles spasms can cause fractures (breaks) of the spine and long bones.
Approximately 30% of the people who get tetanus will die from the disease.
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- Varicella (Chickenpox):
- Varicella is a highly contagious disease. Symptoms of the disease include fever, general
feeling of illness and a rash of blister-like bumps. The virus is transmitted from person to
person primarily by direct contact with infected persons, or from airborne spread of
respiratory secretions. Although considered a common childhood disease, the varicella zoster
virus can reactivate later in life and cause a painful sensory-nerve rash called shingles.
Approximately 100 deaths per year nationally occur from complications of varicella.
Definitions for Vaccines
- ActHIB®
- This vaccine is used to prevent infection caused by Haemophilus influenzae type b bacteria.
- Adacel®
- This is a combination vaccine with tetanus and diphtheria toxoids and acellular pertussis vaccine adsorbed.
- Boostrix®
- This is a combination vaccine with tetanus and diphtheria toxoids and acellular pertussis vaccine adsorbed.
- Cervarix®
- This vaccine is used to prevent human papillomavirus infection.
- Comvax®
- This vaccine is used to prevent infection by Haemophilus influenzae type b bacteria and hepatitis B virus.
- Daptacel®
- This is a combination vaccine with diphtheria and tetanus toxoids and acellular pertussis vaccine adsorbed.
- Decavac®
- This is a combination vaccine with tetanus and diphtheria toxoids for adults.
- Engerix-B®
- This vaccine is used to prevent hepatitis B infection.
- Gardasil®
- This vaccine is used to prevent human papillomavirus infection.
- Havrix®
- This vaccine is used to prevent hepatitis A infection.
- HBIg
- Hepatitis B immune globulin is a sterile solution of immune globulins against hepatitis B
surface antigen (HBsAg). Anti-HBsAg antibodies are collected from individuals with high titers of anti-HBsAg. HBIg undergoes processing to
inactivate and remove viruses including hepatitis B,
hepatitis C, hepatitis A, parvovirus B19, and HIV.
- Hiberix®
- This vaccine is used to prevent infection by Haemophilus influenzae type b bacteria.
- Infanrix™
- This is a combination vaccine with diphtheria and tetanus toxoids and acellular pertuss vaccine adsorbed.
- IPOL®
- This is an inactivated polio vaccine.
- Kinrix®
- This is a combination vaccine with diphtheria and tetanus toxoids and acellular pertussis combined with inactivated polio vaccine.
- Menomune®
- This is a polysaccharide vaccine for prevention of meningococcal.
- Menactra®
- This is a polysaccharide conjugate vaccine for prevention of meningococcal.
- Menveo®
- This is a polysaccharide conjugate vaccine for prevention of meningococcal.
- M-M-R® II
- This is a combination vaccine used to prevent measles, mumps, and rubella.
- Pediarix®
- This is a combination vaccine with diphtheria and tetanus toxoids and acellular pertussis combined with hepatitis B, and inactivated polio vaccine.
- PedvaxHIB®
- This vaccine is used to prevent infections caused by Haemophilus influenzae type b bacteria.
- Pentacel®
- This is a combination vaccine with diphtheria and tetanus toxoids and acellular pertussis combined with inactivated polio, and a vaccine to
prevent infections caused by Haemophilus influenzae type
b bacteria.
- Pneumovax® 23
- This vaccine is used to prevent infections caused by pneumococcal bacteria.
- Prevnar®
- This is a vaccine to protect infants and toddlers from life-threatening meningitis and infection of the blood stream caused by
pneumococcal bacteria.
- ProQuad®
- This is a combination vaccine used to prevent measles, mumps, rubella, and varicella.
- Rotarix®
- This vaccine is used to prevent rotavirus infection.
- RotaTeq®
- This vaccine is used to prevent rotavirus infection.
- Recombivax HB®
- This vaccine is used to prevent hepatitis B infection.
- TriHIBiT®
- This is a combination vaccine with diphtheria and tetanus toxoids and acellular pertussis combined with vaccine to
prevent infections caused by Haemophilus influenzae type
b bacteria. This vaccine is ActHIB® that
is reconstituted with Tripedia®.
- Tripedia®
- Diphtheria and tetanus toxoids and acellular pertussis vaccine adsorbed.
- Twinrix®
- This vaccine is used to prevent hepatitis A and hepatitis B infection.
- VAQTA®
- This vaccine prevents persons from infections caused by the hepatitis A infection.
- Varivax®
- This vaccine is used to prevent varicella (chickenpox) infection.
- Zostavax®
- This vaccine is used to prevent herpes zoster (shingles) infection.
Definitions for Medical Terminology
- 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 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 U.S. 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.
- Chickenpox-
- See Varicella.
- 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.
- 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 U.S. include measles, mumps, rubella, polio,
yellow fever and varicella. Also known as an attenuated vaccine.
- Lock Jaw-
- See Tetanus.
- 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 from 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 U.S. Reports to VAERS can
be made by the vaccine manufacturer, recipient, their parent/guardian or healthcare provider.
- Vaccine Safety Datalink Project (VSD)-
- In order to increase knowledge about vaccine adverse events, the Centers for Disease
Control and Prevention has 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.
- 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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