Glosario de términos

A

Vacuna acelular: Listen[MP3-105 KB]
vacuna que contiene partes de células en lugar de células completas.

Acquired Immune Deficiency Syndrome (AIDS): A medical condition where the immune system cannot function properly and protect the body from disease. As a result, the body cannot defend itself against infections (like pneumonia). AIDS is caused by the Human Immunodeficiency Virus (HIV). This virus is spread through direct contact with the blood and body fluids of an infected individual. High risk activities include unprotected sexual intercourse and intravenous drug use (sharing needles). There is no cure for AIDS, however, research efforts are on-going to develop a vaccine.

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:Listen[MP3-89 KB]
efecto sobre la salud intenso y de corto plazo.

Adjuvant:Listen[MP3-86 KB]
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.

Alergia: afección donde el cuerpo tiene una respuesta exagerada ante una sustancia (por ejemplo, alimento o medicamento). También conocida como hipersensibilidad.

Anaphylaxis: Listen[MP3-91 KB]
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.

Anthrax:Listen[MP3-89 KB]
An acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in hoofed mammals and can also infect humans.

Antibiotic: Listen[MP3-89 KB]
A substance that fights bacteria.

Antibody:Listen[MP3-90 KB]
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:Listen[MP3-90 KB]
sustancias extrañas (por ej., bacterias o virus) en el cuerpo capaces de causar enfermedades. The presence of antigens in the body triggers an immune response, usually the production of antibodies.

Antitoxin: Listen[MP3-89 KB]
Antibodies capable of destroying toxins generated by microorganisms including viruses and bacteria.

Antiviral: Literally "against-virus" -- any medicine capable of destroying or weakening a virus.

Arthralgia: Listen[MP3-89 KB]
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.

Asthma: A chronic medical condition where the bronchial tubes (in the lungs) become easily irritated. This leads to constriction of the airways resulting in wheezing, coughing, difficulty breathing and production of thick mucus. The cause of asthma is not yet known but environmental triggers, drugs, food allergies, exercise, infection and stress have all been implicated.

Asymptomatic infection: Listen[MP3-103 KB]
The presence of an infection without symptoms. Also known as inapparent or subclinical infection.

Vacuna atenuada: Listen[MP3-100 KB]
versión donde el virus vivo ha sido debilitado a través de procesos químicos o físicos para producir una respuesta inmunitaria sin causar los efectos graves de la enfermedad. Actualmente en Estados Unidos se encuentran autorizadas vacunas atenuadas contra sarampión, paperas, rubéola, poliomielitis, fiebre amarilla y varicela. 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.

B

Células B: pequeños glóbulos blancos que ayudan al cuerpo a defenderse contra infecciones. Estas células se generan en la médula ósea y se convierten en células plasmáticas que producen anticuerpos. También se denominan linfocitos B.

Bacterias: pequeños organismos unicelulares presentes en todo el medioambiente que son visibles solamente a través de un microscopio. No todas las bacterias son dañinas, pero algunas causan enfermedades. Examples of bacterial disease include diphtheria, pertussis, tetanus, Haemophilus influenzae, and pneumococcal.

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.

Brachial neuritis: Listen[MP3-95 KB]
Inflammation of nerves in the arm causing muscle weakness and pain.

Breakthrough infection: Development of a disease despite a person's having responded to a vaccine.

C

Causal association: Listen[MP3-99 KB]
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.

Condición crónica de salud: estado relacionado con la salud que dura un largo periodo (por ejemplo: cáncer, asma)

Combination vaccine: Two or more vaccines administered in a single dose in order to reduce the number of shots given. For example, the MMR (measles, mumps, rubella) vaccine.

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

Crohn's disease: Listen[MP3-95 KB]
A chronic medical condition characterized by inflammation of the bowel. Symptoms include abdominal pain, diarrhea, fever, loss of appetite and weight loss. The cause of Crohn's disease is not yet known, but genetic, dietary and infectious factors may play a part.

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: Listen[MP3-97 KB]
The joining together of two compounds (usually a protein and polysaccharide) to increase a vaccine's effectiveness.

Conjunctivitis: Listen[MP3-95 KB]
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: Listen[MP3-98 KB]
A condition in a recipient which is likely to result in a life-threatening problem if a vaccine were given.

Convulsion: See Seizure.

Crib or Cot Death: See Sudden Infant Death Syndrome (SIDS).

D

Deltoid:Listen[MP3-86 KB]
A muscle in the upper arm where shots are usually given.

Demyelinating disorders: Listen[MP3-127 KB]
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.

Difteria: Listen[MP3-87 KB]
enfermedad bacteriana caracterizada por la formación de una membrana falsa, especialmente en la garganta, que puede provocar la muerte.

Disease: Sickness, illness or loss of health.

E

Efficacy rate: Listen[MP3-95 KB]
A measure used to describe how good a vaccine is at preventing disease.

Encefalitis: Listen[MP3-93 KB]
inflamación del cerebro causada por un virus. La encefalitis puede provocar daño cerebral permanente o la muerte.

Encephalopathy: Listen[MP3-90 KB]
A general term describing brain dysfunction. Examples include encephalitis, meningitis, seizures and head trauma.

Epidemic:Listen[MP3-87 KB]
The occurrence of disease within a specific geographical area or population that is in excess of what is normally expected.

Endemic:Listen[MP3-87 KB]
la presencia de bajo nivel pero constante de una enfermedad en una comunidad.

Erythema Multiforme: Listen[MP3-117 KB]
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:Listen[MP3-107 KB]
The cause of.

Exposure: Contact with infectious agents (bacteria or viruses) in a manner that promotes transmission and increases the likelihood of disease.

F

Febrile:Listen[MP3-104 KB]
Relating to fever; feverish.

G

Guillain-Barre Syndrome (GBS): Listen[MP3-106 KB]
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.

H

Haemophilus influenzae type b (Hib): Listen[MP3-114 KB]
A bacterial infection that may result in severe respiratory infections, including pneumonia, and other diseases such as meningitis.

Hepatitis A: enfermedad viral leve que generalmente no permanece en la sangre y se transmite por la ingestión de agua o alimentos contaminados.

Hepatitis B: enfermedad viral transmitida por la sangre o productos sanguíneos infectados, o a través de relaciones sexuales sin protección con alguien infectado.

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.

Herpes Zóster: 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.

Ronchas: Ronchas erupción de marcas rojas en la piel, generalmente acompañadas por picazón. Esta afección puede ser causada por una alergia (por ejemplo, a alimentos o medicamentos), estrés, infección o agentes físicos (por ejemplo, frío o calor). También conocidas como urticaria.

Hypersensitivity: Listen[MP3-93 KB]
afección donde el cuerpo tiene una respuesta exagerada ante una sustancia (por ejemplo, alimento o medicamento). Also known as an allergy.

Hyposensitivity: Listen[MP3-98 KB]
A condition in which the body has a weakened or delayed reaction to a substance.

I

Inmunoglobulina: Listen[MP3-93 KB]
proteína que se encuentra en la sangre para combatir la infección. También conocida como gamma globulina.

Sistema inmunológico: 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.

Inmunidad: protección contra una enfermedad. Existen dos tipos de inmunidad: La inmunidad está indicada por la presencia de anticuerpos en la sangre y, en general, puede ser determinada por una prueba de laboratorio. See active and passive immunity.

Immunization: Listen[MP3-89 KB]
The process by which a person or animal becomes protected against a disease. This term is often used interchangeably with vaccination or inoculation.

Immunosupression: Listen[MP3-93 KB]
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.

Vacuna inactivada: Listen[MP3-100 KB]
formulada con bacterias y virus muertos a través de procesos físicos o químicos. Estos organismos muertos no pueden causar la enfermedad.

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).

Inflamación: enrojecimiento, hinchazón, calor y dolor como producto de una lesión de los tejidos (partes del cuerpo que se encuentran debajo de la piel). También conocida como hinchazón.

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.

Influenza: A highly contagious viral infection characterized by sudden onset of fever, severe aches and pains, and inflammation of the mucous membrane.

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.

J

Jaundice:Listen[MP3-87 KB]
coloración amarillenta de la piel y los ojos. Esta afección es generalmente un síntoma de infección por hepatitis.

L

Lesion:Listen[MP3-88 KB]
An abnormal change in the structure of an organ, due to injury or disease.

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.

Lupus: A disease characterized by inflammation of the connective tissue (which supports and connects all parts of the body). Chronic swelling of the connective tissue causes damage to the skin, joints, kidneys, nervous system and mucous membranes. The disease begins with fever, joint pain and fatigue. Additional symptoms continue to develop over the years including nausea, fatigue, weight loss, arthritis, headaches and epilepsy. Problems with heart, lung and kidney function may also result. This condition is diagnosed most frequently in young women but also occurs in children.

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. A vaccine was available from 1998 to 2002.

Lymphocytes: Listen[MP3-95 KB]
pequeños glóbulos blancos que ayudan al cuerpo a defenderse contra infecciones. Estas células se generan en la médula ósea y se convierten en células plasmáticas que producen anticuerpos. Also known as B cells.

M

Macrophage: Listen[MP3-95 KB]
A large cell that helps the body defend itself against disease by surrounding and destroying foreign organisms (viruses or bacteria).

Macular:Listen[MP3-88 KB]
Skin lesions, normally red-colored.

Sarampión: enfermedad viral contagiosa caracterizada por erupciones rojas y circulares en la piel.

Célula de memoria: A group of cells that help the body defend itself against disease by remembering prior exposure to specific organisms (e.g. viruses or bacteria). Por lo tanto, estas células pueden responder rápidamente cuando estos organismos amenazan reiteradamente el cuerpo.

Meningitis: Listen[MP3-95 KB]
inflamación del cerebro y la médula espinal que provoca daño cerebral permanente y muerte.

Meningoencephalitis: Listen[MP3-99 KB]
["men in joe en sef uh LIGHT iss"] -- inflammation of the brain and meninges (membranes) that involves the encephalon (area inside the skull) and spinal column.

Microbes:Listen[MP3-87 KB]
pequeños organismos (virus y bacterias incluidos) que se pueden ver únicamente a través de un microscopio.

Mucosal membranes: Listen[MP3-99 KB]
The soft, wet tissue that lines body openings specifically the mouth, nose, rectum and vagina.

Multiple Sclerosis: Listen[MP3-102 KB]
Multiple sclerosis (MS) 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.

Paperas: Acute contagious viral illness marked by swelling, especially of the parotid glands.

N

Neuritis:Listen[MP3-91 KB]
Inflammation of the nerves.

Neuropathy: Listen[MP3-91 KB]
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.

O

Optic neuritis: Listen[MP3-99 KB]
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.

Orchitis:Listen[MP3-89 KB]
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: Listen[MP3-97 KB]
infección viral o bacteriana que produce la inflamación del oído medio. En general, esta afección está acompañada de una infección de la vía respiratoria superior. Los síntomas incluyen dolor de oído, fiebre alta, náuseas, vómitos y diarrea. Además, puede provocar pérdida de la audición, parálisis facial y meningitis.

Brote: aparición repentina de una enfermedad en un área geográfica específica (por ej.: un vecindario o una comunidad) o población (por ej., adolescentes).

P

Pandemia: An epidemic occurring over a very large geographic area.

Papular:Listen[MP3-85 KB]
Marked by small red-colored elevation of the skin.

Inmunidad pasiva: protección contra enfermedades mediante los anticuerpos producidos por otro ser humano o animal. La inmunidad pasiva es efectiva, pero la protección es generalmente limitada y disminuye con el tiempo (normalmente un par de semanas o meses). Por ejemplo, los anticuerpos maternos se transmiten al bebé durante la gestación. Estos anticuerpos protegen temporalmente al bebé durante los primeros 4 a 6 meses de vida.

Pathogens: Organisms (e.g. bacteria, viruses, parasites and fungi) that cause disease in human beings.

Tos ferina: Listen[MP3-89 KB]
(whooping cough) Bacterial infectious disease marked by a convulsive spasmodic cough, sometimes followed by a crowing intake of breath.

Petechiae: Listen[MP3-88 KB]
["pe TEEK ee ay"] -- a tiny reddish or purplish spot on the skin or mucous membrane, commonly part of infectious diseases such as typhoid fever.

Placebo: A substance or treatment that has no effect on human beings.

Neumonía: Listen[MP3-87 KB]
inflamación de los pulmones caracterizada por fiebre, escalofríos, rigidez muscular, dolor en el pecho, tos, falta de aire, frecuencia cardíaca acelerada y dificultad para respirar.

Poliomielitis: Listen[MP3-105 KB]
enfermedad viral aguda e infecciosa, caracterizada por fiebre, parálisis y atrofia de los músculos esqueléticos.

Vacunas polisacáridas: Listen[MP3-108 KB]
vacunas compuestas por largas cadenas de moléculas de azúcar similares a la superficie de ciertos tipos de bacterias. Las vacunas polisacáridas están disponibles para enfermedades neumocócicas, enfermedades meningocócicas y Haemophilus Influenzae tipo 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.

Prodromal: Listen[MP3-88 KB]
An early symptom indicating the onset of an attack or a disease.

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.

R

Recombinant: Listen[MP3-97 KB]
Of or resulting from new combinations of genetic material or cells; the genetic material produced when segments of DNA from different sources are joined to produce recombinant DNA.

Reye Syndrome: Listen[MP3-115 KB]
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 seizures.

Risk: The likelihood that an individual will experience a certain event.

Rotavirus: Listen[MP3-91 KB]
A group of viruses that cause diarrhea in children.

Rubéola: (rubéola alemana) infección viral más leve que el sarampión normal, pero igualmente peligrosa para el feto cuando aparece en la primera etapa del embarazo.

Rubeola:Listen[MP3-87 KB]
See Measles.

S

Seroconversion: Listen[MP3-95 KB]
Development of antibodies in the blood of an individual who previously did not have detectable antibodies.

Serology:Listen[MP3-91 KB]
Measurement of antibodies, and other immunological properties, in the blood serum.

Serosurvey: Listen[MP3-96 KB]
Study measuring a person's risk of developing a particular disease.

Convulsión: la aparición súbita de espasmos y crisis de ausencia por lo general causada por fiebre. También conocida como ataque convulsivo.

Severe Combined immune Deficiency (SCID): Included in a group of rare, life-threatening disorders caused by at least 15 different single gene defects that result in profound deficiencies in T- and B- lymphocyte function.

Shingles: See herpes zoster.

Side Effect: Undesirable reaction resulting from immunization.

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.

Cepa: 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.

Sudden Infant Death Syndrome (SIDS): The sudden and unexpected death of a healthy infant under 1 year of age. A diagnosis of SIDS is made when an autopsy cannot determine another cause of death. The cause of SIDS is unknown. Also known as "crib" or "cot" death.

Susceptible: Unprotected against disease.

T

Temporal association: Two or more events that occur around the same time but may be unrelated, chance occurrences.

Teratogenic: Listen[MP3-92 KB]
Of, relating to, or causing developmental malformations.

Tetanus:Listen[MP3-89 KB]
enfermedad bacteriana productora de toxinas y caracterizada por espasmos musculares dolorosos.

Thimerosal: Listen[MP3-115 KB]
Thimerosal is a mercury-containing preservative used in some vaccines and other products since the 1930's. There is no convincing evidence of harm caused by the low concentrations of thimerosal in vaccines, except for minor reactions like redness and swelling at the injection site. However, in July 1999, the Public Health Service agencies, the American Academy of Pediatrics, and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure. Today, all routinely recommended childhood vaccines manufactured for the U.S. market contain either no thimerosal or only trace amounts with the exception of some flu vaccines. There are thimerosal-free influenza vaccines available.

Fiebre tifoidea: Typhoid fever is a life-threatening illness caused by the bacterium Salmonella Typhi. Persons with typhoid fever carry the bacteria in their bloodstream and intestinal tract.

Titer:Listen[MP3-88 KB]
The detection of antibodies in blood through a laboratory test.

Transverse Myelitis: Listen[MP3-107 KB]
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.

U

Urticaria: Listen[MP3-108 KB]
Ronchas erupción de marcas rojas en la piel, generalmente acompañadas por picazón. Esta afección puede ser causada por una alergia (por ejemplo, a alimentos o medicamentos), estrés, infección o agentes físicos (por ejemplo, frío o calor). Also known as hives.

V

Vaccination: Listen[MP3-93 KB]
Injection of a killed or weakened infectious organism in order to prevent the disease.

Vaccinia:Listen[MP3-85 KB]
A virus related to the smallpox and cowpox viruses, which is used in smallpox vaccine.

Vaccine:Listen[MP3-84 KB]
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. For more information on VAERS call (800) 822-7967.

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 eight 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.

Varicela: Listen[MP3-93 KB]
(Chickenpox) -- An acute contagious disease characterized by papular and vesicular lesions.

Variola:Listen[MP3-94 KB]
See smallpox.

Vesicular: Listen[MP3-90 KB]
Characterized by small elevations of the skin containing fluid (blisters).

Viremia:Listen[MP3-91 KB]
The presence of a virus in the blood.

Virulence: Listen[MP3-86 KB]
The relative capacity of a pathogen to overcome body defenses.

Virus: diminuto organismo que se multiplica en las células y provoca enfermedades como varicela, sarampión, paperas, rubéola, tos ferina y hepatitis. Los virus no se eliminan con antibióticos, los medicamentos utilizados para combatir las bacterias.

W

Waning Immunity: The loss of protective antibodies over time.

Whooping Cough: See Pertussis.