Vaccination: Injection of a killed microbe in order to stimulate the immune system against the microbe, thereby preventing disease. Vaccinations, or immunizations, work by stimulating the immune system, the natural disease-fighting system of the body. The healthy immune system is able to recognize invading bacteria and viruses and produce substances (antibodies) to destroy or disable them. Immunizations prepare the immune system to ward off a disease. To immunize against viral diseases, the virus used in the vaccine has been weakened or killed. To only immunize against bacterial diseases, it is generally possible to use a small portion of the dead bacteria to stimulate the formation of antibodies against the whole bacteria. In addition to the initial immunization process, it has been found that the effectiveness of immunizations can be improved by periodic repeat injections or "boosters." Also see Vaccines (in the plural) and Vaccine of a specific type (such Vaccine, Polio).

Vaccination, anthrax: A series of six shots over six months and booster shots annually, the anthrax vaccine now in use in the USA was first developed in the 1950s and approved by the Food and Drug Administration for general use in 1970. It is produced by the Michigan Biologic Products Institute of Michigan’s Department of Health and is given routinely to veterinarians and others working with livestock. In December, 1997 it was announced that all US military would receive the vaccine, as do the military in the UK and Russia, the reason being concern that anthrax might be used in biologic warfare.

Vaccination, children’s: In the United States, it is recommended that all children receive vaccination against: - Hepatitis B - Diphtheria, tetanus, pertussis - Haemophilus influenzae type B (HIB)

- Poliovirus

- Measles, mumps, rubella

- Varicella zoster virus (chickenpox). Every child in the U.S. should have these vaccinations except when there are special circumstances and the child’s doctor advises specifically against a vaccination..

Vaccination, chickenpox: This vaccine prevents the common disease known as chickenpox (varicella zoster). While chickenpox is often considered a trivial illness, it can cause significant lost time on the job and in school and have serious complications including ear infections, pneumonia, and infection of the rash with bacteria, inflammation of the brain (encephalitis) leading to difficulty with balance and coordination (cerebellar ataxia), damaged nerves (palsies), and Reye’s syndrome, a potentially fatal complication. The vaccination requires only one shot given at about a year of age. If an older person has not had chickenpox, the shot may be given at any time. There have been few significant reactions to the chickenpox vaccine. All children, except those with a compromised immune system, should have the vaccination.

Vaccination, DTaP: Like DPT, DTaP protects from diphtheria, pertussis (whooping cough) and tetanus. DTaP is the same as DTP, except that it contains only acellular pertussis vaccine which is thought to cause fewer of the minor reactions associated with immunization and is also probably less likely to cause the more severe reactions occasionally seen following pertussis vaccination. DTaP is currently recommended only for the shots given at 18 months and 4-6 years of age.

Vaccination, DT: DT (diphtheria and tetanus) vaccine does not protect from pertussis and is usually reserved for individuals who have had a significant adverse reaction to a DPT shot or who have a personal or family history of a seizure disorder or brain disease

Vaccination, German measles: See Vaccination, MMR.

Vaccination, Haemophilus influenzae type B: See Vaccination, HIB.

Vaccination, hepatitis A: When immediate protection against hepatitis A (infectious hepatitis) is needed, immunoglobulins are used. Protection is effective only if given within 2 weeks of exposure and lasts but 2-4 months. Immunoglobulins can be used to protect household contacts of someone with acute viral hepatitis and travelers to regions with poor sanitation and high hepatitis A rates, when the traveler has to depart sooner than the vaccines can take effect (about 2 weeks). Travelers can receive the immunoglobulin and vaccine simultaneously and be protected immediately and for longer term. When immediate protection is not needed, hepatitis A vaccines are considered for individuals in high-risk settings, including frequent world travelers, sexually active individuals with multiple partners, homosexual men, individuals using illicit drugs, employees of daycare centers, and certain health care workers, and sewage workers. Two hepatitis A vaccines called HAVRIX and VAQTA are commercially available in the U.S. Both are highly effective and provide protection even after only one dose. Two doses are recommended for adults and 3 doses for children (under 18 years of age) to provide prolonged protection.

Vaccination, hepatitis B: Hepatits B (hep B) vaccine gives prolonged protection, but 3 shots over a half year are usually required. In the U.S., all infants receive hep B vaccine. Two vaccines (ENGERIX-B, and RECOMBIVAX-HB) are available in the US. The first dose of hep B vaccine is frequently given while the newborn is in the hospital or at the first doctor visit following birth. The second dose is given about 30 days after the initial dose. A booster dose is performed approximately six months later. Babies born to mothers testing positive for hep B receive, in addition, HBIG (hep B immune globulin) for prompt protection. Older children (11-12 years) are advised to receive a hep B booster as are adults in high-risk situations including healthcare workers, dentists, intimate and household contacts of patients with chronic hep B infection, male homosexuals, individuals with multiple sexual partners, dialysis patients, IV drug users, and recipients of repeated transfusions. Health care workers accidentally exposed to materials infected with hep B (such as needle sticks), and individuals with known sexual contact with hep B patients are available in the U.S. Both are highly effective and provide protection even after only one dose. Two doses are recommended for adults and 3 doses for children (under 18 years of age) to provide prolonged protection. Vaccination, hepatitis B: Hepatits B (hep B) vaccine gives prolonged protection, but 3 shots over a half year are usually required. In the U.S., all infants receive hep B vaccine. Two vaccines (ENGERIX-B, and RECOMBIVAX-HB) are available in the US. The first dose of hep B vaccine is frequently given while the newborn is in the hospital or at the first doctor visit following birth. The second dose is given about 30 days after the initial dose. A booster dose is performed approximately six months later. Babies born to mothers testing positive for hep B receive, in addition, HBIG (hep B immune globulin) for prompt protection. Older children (11-12 years) are advised to receive a hep B booster as are adults in high-risk situations including healthcare workers, dentists, intimate and household contacts of patients with chronic hep B infection, male homosexuals, individuals with multiple sexual partners, dialysis patients, IV drug users, and recipients of repeated transfusions. Health care workers accidentally exposed to materials infected with hep B (such as needle sticks), and individuals with known sexual contact with hep B patients are usually given both HBIG and vaccine to provide immediate and long term protection.

Vaccination, H. flu: See Vaccination, HIB.

Vaccination, HIB: This vaccine is to prevent disease caused by the Haemophilus influenzae type B (HIB) bacteria. The H. influenzae (H. flu) bacteria can cause a range of serious diseases including meningitis with potential brain damage and epiglottitis with airway obstruction poisoning. The HIB vaccine is usually given at 2, 4 and 6 months of age. A final booster is given at 12-15 months of age. HIB vaccine rarely causes severe reactions.

Vaccination, infectious hepatitis: See Vaccination, hepatitis A.

Vaccination, measles: See Vaccination, MMR. Vaccination, MMR: The standard vaccine given to prevent measles, mumps and rubella (German measles). The MMR vaccine is now given in two dosages. The first should be given at12-15 months of age. The second vaccination hould be given at 4-6 years (or, alternatively, 11-12 years) of age. Most colleges require proof of a second measles or MMR vaccination prior to entrance. Most children should receive MMR vaccinations. Exceptions may include children born with an inability to fight off infection, some children with cancer, on treatment with radiation or drugs for cancer, on long term steroids (cortisone). People with severe allergic reactions to eggs or the drug neomycin should probably avoid the MMR vaccine. Pregnant women should wait until after delivery before being immunized with MMR. People with HIV or AIDS should normally receive MMR vaccine. Measles, mumps, and rubella vaccines may be administered as individual shots, if necessary, or as a measles-rubella combination.

Vaccination, mumps: See Vaccination, MMR. Vaccination, pneumococcal pneumonia: This vaccine, which prevents one of the most common and severe forms of pneumonia, is usually given only once in a lifetime, usually after the age of 55, to someone with ongoing lung problems (such as chronic obstructive pulmonary disease (COPD) or asthma) or other chronic diseases (including those involving the heart and kidneys). This vaccination would rarely be given to children.

Vaccination, polio: The vaccines available for vaccination against polio are OPV (Oral Polio Vaccine) and IPV (Inactivated Polio Vaccine). OPV is still the preferred vaccine for most children. As its name suggests, it is given by mouth. IPV, or Inactivated Polio Vaccine is given as a shot in the arm or leg. Infants and children should be given four doses of OPV. The doses are given at 2 months, 4 months, 6-18 months and 4-6 years of age. Persons allergic to eggs or the drugs neomycin or streptomycin should receive OPV, not the injectable IPV. Conversely, IPV should be given If the vaccine recipient is on long-term steroid (cortisone) therapy, has cancer, or is on chemotherapy or if a household member has AIDS or there is an unimmunized adult in the house.

Vaccination, rubella: See Vaccination, MMR.

Vaccineation, serum hepatitis: See Vaccination, hepatitis B.

Vaccination, Td: Td is the vaccine given to children over six and adults as boosters for immunity to diphtheria and tetanus.

Vaccination, varicella zoster: See Vaccineation, chickenpox.

Vaccination, DPT: DPT immunization protects from diphtheria, pertussis (whooping cough), and tetanus and is given in a series of 5 shots at 2, 4, 6, 18 months of age and 4-6 years of age. Thanks to vaccination programs, these diseases have become less common. However, there are still unvaccinated individuals capable of carrying and passing diphtheria and pertussis to others who are not vaccinated. Tetanus bacteria are prevalent in natural surroundings, such as contaminated soil. See also Vaccination, DTaP.

Vaccine, flu: The flu (influenza) vaccine is recommended for persons at high risk for serious complications from influenza infection, including everyone 65 or over; people with chronic diseases of the heart, lung or kidneys, diabetes, immunosuppression, or severe forms of anemia; residents of nursing homes and other chronic-care facilities, children and teenagers taking aspirin therapy (and who may therefore be at risk for developing Reye syndrome after an influenza infection), and those in close or frequent contact with anyone at high risk. Persons with an allergy to eggs should not receive influenza vaccine.

Vaccine, influenza: See Vaccine, flu. Vaccination, DTaP: Like DPT, DTaP protects from diphtheria, pertussis (whooping cough) and tetanus. DTaP is the same as DTP, except that it contains only acellular pertussis vaccine which is thought to cause fewer of the minor reactions associated with immunization and is also probably less likely to cause the more severe reactions occasionally seen following pertussis vaccination. DTaP is currently recommended only for the shots given at 18 months and 4-6 years of age. Vaccination, DT: DT (diphtheria and tetanus) vaccine does not protect from pertussis and is usually reserved for individuals who have had a significant adverse reaction to a DPT shot or who have a personal or family history of a seizure disorder or brain disease.

Vaccination, hepatitis A: When immediate protection against hepatitis A (infectious hepatitis) is needed, immunoglobulins are used. Protection is effective only if given within 2 weeks of exposure and lasts but 2-4 months. Immunoglobulins can be used to protect household contacts of someone with acute viral hepatitis and travelers to regions with poor sanitation and high hepatitis A rates, when the traveler has to depart sooner than the vaccines can take effect (about 2 weeks). Travelers can receive the immunoglobulin and vaccine simultaneously and be protected immediately and for longer term. When immediate protection is not needed, hepatitis A vaccines are cons idered for individuals in high-risk settings,

Vaccination, German measles: See Vaccination, MMR.

Vaccination, Haemophilus influenzae type B: See Vaccination, HIB.

Vagina: The muscular canal extending from the cervix to the outside of the body. The word "vagina" is a Latin word meaning "a sheath or scabbard", a scabbard into which one might slide and sheath a sword. The "sword" in the case of the anatomic vagina was the penis. Love and war, it would seem, have been connected in the minds of people for millenia.

Vaginal hysterectomy: Removal of the uterus through a surgical incision, not of the abdomen but, within the vagina. With a vaginal hysterectomy, the scar is not outwardly visible. A vaginal hysterectomy is as opposed to an abdominal hysterectomy.

Vagina, septate: A vagina that is divided, usually longitudinally, to create a double vagina. This situation can be easily missed by the patient and even by the doctor on exam. If the patient becomes sexually active prior to diagnosis, one of the vaginas stretches and becomes "dominant". The other vagina slips slightly upward and flush and is a little difficult to enter.

Vaginitis: Inflammation of the vagina. The vagina is the muscular canal extending from the cervix to the outside of the body.

VAQTA: A vaccine against hepatitis A made of killed hepatitis A virus to stimulate the body’s immune system to produce antibodies against the hepatitis A virus.

Varicella: A highly infectious viral disease, known familiarly as chickenpox. The "pox" of chickenpox is no major matter unless infected (through scratching) or occur in an immunodeficient person. However, there can be very major complications from chickenpox including pneumonia and encephalitis, particularly in adults but also sometimes in children. Reactivation of the same herpes virus to cause inflammation along a nerve of sensation is reponsible for shingles (zoster). The current aim in the U.S. is to achieve universal (or nearly universal) immunization of children with the chickenpox vaccine.

Varicella vaccination: See Vaccination, chickenpox.

Varicocele: Elongation and enlargement of the veins of the pampiniform plexus (the network of veins leaving the testis which join to form the testicular vein). Appears bluish through the scrotum and feels like a bag of worms. Can cause pain or discomfort.

Varix: An enlarged and convoluted vein, artery or lymphatic vessel.

Vasa previa: The umbilical cord vessels come before the fetal head during delivery.

Vascular headache: A group of headaches felt to involve abnormal sensitivity of the blood vessels (arteries) in the brain to various triggers which results in rapid changes in the artery size due to spasm (constriction). Other arteries in the brain and scalp then open (dilate), and throbbing pain is perceived in the head. Migraine headaches are the most common type of vascular headache.

Vascular endothelial growth factor (VEG-F): A gene that is responsible for the growth of blood vessels.

Vasoconstriction: Narrowing of the blood vessels resulting from contracting of the muscular wall of the vessels. The opposite of vasodilation.

Vasodilation: Widening of blood vessels resulting from relaxation of the muscular wall of the vessels. What widens is actually the diameter of the interior (the lumen) of the vessel. The opposite of vasoconstriction.

Vasodilators: Agents that act as blood vessel dilators (vasodilators) and open vessels by relaxing their muscular walls. For example, nitroglycerin is a vasodilator. So are the ACE (angiotensin converting enzyme) inhibitors.

Vector: In medicine, a vector is a carrier. The best way to understand a vector is to recall its origin as a word. Vector is the Latin word for a "bearer." It is often an intermediary vehicle. For example, in malaria where the mosquito serves as a vector that carries and transfers the infectious agent (Plasmodium) injecting it with a bite. In molecular biology, a vector may be a virus (or a plasmid); a piece of foreign DNA is inserted in the vector genome to be carried and introduced into a recipient (host) cell. In physics, there are vectors but they go beyond the biomedical realm.

VEG-F: Vascular endothelial growth factor.

Vein: A vein is a blood vessel that carries blood low in oxygen content from the body to the lungs and heart. It is part of the circulatory system.

Velo-cardio-facial (VCF) syndrome: Also known as Shprintzen syndrome, this > is a congenital malformation (birth defect) syndrome with cleft palate, heart defect, abnormal face, and learning problems. The condition is therefore called the velo-cardio-facial (VCF) syndrome. (The velum is the soft palate). Other less frequent features include short stature, small-than-normal head (microcephaly), mental retardation, minor ear anomalies, slender hands and digits, and inguinal hernia. The cause is usually a microdeletion in chromosome band 22q11.2, just as in DiGeorge syndrome. VCF and DiGeorge syndromes are different clinical expressions of essentially the same chromosome defect. of essentially the same chromosome defect.

Velvet ant stings: Common in most parts of the world including the Southern and Southwestern United States, velvet ants are not true ants but rather parasitic wasps. Their sting—like that of other wasps, fire ants, bees, yellow jackets, and hornets -- can trigger allergic reactions varying greatly in severity. Avoidance and prompt treatment are essential. In selected cases, allergy injection therapy is highly effective. (The three "A’s" of insect allergy are Adrenaline, Avoidance and Allergist.)

Vena cava: The superior vena cava is the large vein which returns blood to the heart from the head, neck and both upper limbs. The inferior vena cava returns blood to the heart from the lower part of the body.

Venereal: Having to do with sexual contact. The word venereal comes from Venus, the Roman godess of love. A venereal disease (a morbus venereus) is contracted and transmitted by sexual contact.

Venereal warts: Warts confined primarily to the moist skin of the genitals due to viruses belonging to the family of human papilloma viruses (HPVs) transmitted through sexual contact. Most infected people have no symptoms but these viruses increase a woman’s risk for cancer of the cervix. The virus can also be transmitted from mother to baby during childbirth. HPV infection is the most common sexually transmitted disease in the United States. It is also the leading cause of abnormal PAP smears and pre-cancerous changes of the cervix in women. There is no cure for genital warts virus infection. Once contracted, the virus can stay with a person for life.

Ventral: The front or anterior side of a structure.

Ventricular arrhythmias: Abnormal rapid heart rhythms (arrhythmias) that originate in the lower chambers of the heart (the ventricles). Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation. Both are life threatening arrhythmias most commonly associated with heart attacks or scarring of the heart muscle from previous heart attack.

Ventricular fibrillation: An abnormal irregular heart rhythm whereby there are very rapid uncoordinated fluttering contractions of the lower chambers (ventricles) of the heart. Venticular fibrillation disrupts the synchrony between the heartbeat and the pulse beat. Ventricular fibrillation is most commonly associated with heart attacks or scarring of the heart muscle from previous heart attack. It is life threatening. Ventricular fibrillation is most commonly associated with heart attacks or scarring of the heart muscle from previous heart attack. It is life threatening.

Ventricular septal defect (VSD): A hole in the interventricular septum, the wall between the ventricles, the lower chambers of the heart. Commonly called a VSD. VSDs constitute a class of heart deformity that is present at birth (congenital cardiac malformation).

Ventricular septum: The wall separating the lower chambers (the ventricles) of the heart. Also called the interventricular septum.

Ventricular tachycardia: An abnormal heart rhythm that is rapid, regular and originates from an area of the ventricle, the lower chamber of the heart. Ventricular tachycardias are life threatening arrhythmias most commonly associated with heart attacks or scarring of the heart muscle from previous heart attack.

Ventilator: A ventilator is a machine which mechanically assists patients in the exchange of oxygen and carbon dioxide (sometimes referred to as artificial respiration).

Ventricles: Chambers of an organ. For example, the four connected cavities (hollow spaces) in the central brain or the four chambers of the heart.

Vertebra: A vertebra is one of 33 bony segments that form the spinal column of humans. There are 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused into one sacrum bone) and 4 coccygeal (fused into one coccyx bone).

Vertex: The top of the head, in medicine. In Latin, vertex means a whirlpool, whirlwind, top of the mountain, or top of the head, it is thought, because the hairs there often form a whorl. In a vertex delivery, the top of the head comes first.

Vesical: Refers to the urinary bladder. The word comes from the Latin vesica meaning a bag or bladder.

Vesicle: A small skin blister, in dermatology. A small pouch, in anatomy. The word vesicle comes from the Latin diminuitive vesiculum meaning a small bag or bladder.

Vesicular: The adjective for vesicle. A vesicular rash has small blisters on the skin.

Vesicular rickettsiosis: A mild infectious disease first observed in New York City, caused by Rickettsia akari, transmitted from its mouse host by chigger or adult mite bites. There is fever, a dark spot that becomes a small ulcer at the site of the bite, swollen glands (lymphadenopathy) in that region, and a raised blistery (vesicular) rash. Also known as rickettsialpox.

Viral hepatitis: Liver inflammation caused by viruses. Specific hepatitis viruses have been labeled A, B, C, D, E, F, and G. While other viruses can also cause hepatitis, their primary target is not the liver.

Virus: A virus is a microbe which cannot grow or reproduce apart from a living cell. It is smaller in size than a bacterium. Viruses cause most of the common human infections, but are also responsible for causing many rare illnesses. Examples of viral illnesses include the common cold and acquired immunodeficiency disease syndrome (AIDS).

Virus, human papilloma (HPV): A family of over 60 viruses responsible for causing warts. The majority of the viruses produce warts on the hands, fingers, and even the face. Most of these viruses are innocuous, causing nothing more than cosmetic concerns. Several types of HPV are confined primarily to the moist skin of the genitals, producing genital warts and elevating the risk for cancer of the cervix. These viruses that cause wartlike growths on the genitals and contribute to cancer of the cervix are sexually transmitted.

Viruses: Small living particles that can infect cells and change how the cells function. Infection with a virus can cause a person to develop symptoms. The disease and symptoms that are caused depend on the type of virus and the type of cells that are infected.

Vital: Necessary to maintain life. Breathing is a vital function.

Vitamins: Essential nutrients of food required for normal metabolism in the body. Lack of a vitamin in the diet can lead to a vitamin deficiency disease. Overly high doses of some vitamins can also lead to disease.

Vitamin A: Retinol. Carotene compounds reponsible for transmitting light sensation in the retina of the eye. Deficiency leads to night blindness.
Beta carotene: An antioxidant which protects cells against oxidation damage that can lead to cancer. Beta carotene is converted, as needed, to vitamin A. Food sources of beta carotene include vegetables such as carrots, sweet potatoes, spinach and other leafy green vegetables; and fruit such as cantaloupes and apricots. Excessive carotene in the diet can temporarily yellow the skin, a condition called carotenemia, commonly seen in infants fed largely mushed carrots.
Vitamin B1: Thiamin, acts as a coenzyme in body metabolism. Deficiency leads to beriberi, a disease of the heart and nervous system.
Vitamin B2: Riboflavin, essential for the reactions of coenzymes. Deficiency causes inflammation of the lining of the mouth and skin.
Vitamin B3: Niacin, an essential part of coenzymes of body metabolism. Deficiency causes inflammation of the skin, vagina, rectum and mouth, as well as mental slowing.
Vitamin B6: Pyridoxine, a cofactor for enzymes. Deficiency leads to inflammation of the skin and mouth, nausea, vomiting, dizziness , weakness and anemia.
Folate (folic acid): Folic acid is an important factor in nucleic acid synthesis (the genetic material of all cells). Deficiency leads to megaloblastic anemia.
Vitamin B12: An essential factor in nucleic acid synthesis (the genetic material of all cells). Deficiency leads to megaloblastic anemia, as can be seen in pernicious anemia.
Vitamin C: Ascorbic acid, important in the synthesis of collagen, the framework protein for tissues of the body. Deficiency leads to scurvy, characterized by fragile capillaries, poor wound healing, and bone deformity in children.
Vitamin D: A steroid vitamin which promotes absorption and metabolism of calcium and phosphorus. Under normal conditions of sunlight exposure, no dietary supplementation is necessary because sunlight promotes adequate vitamin D synthesis in the skin. Deficiency can lead to osteomalcia in adults and bone deformity (rickets) in children.
Vitamin E: Deficiency can lead to anemia.
Vitamin K: An essential factor in the formation of blood clotting factors. Deficiency can lead to abnormal bleeding.
Vocal cords: Two small bands of muscle within the larynx. They close to prevent food from getting into the lungs, and they vibrate to produce the voice.
Void: To urinate. Just as we can void a check and empty it of value, so can we void our bladder and empty it of urine. According to Merriam Webster’s Collegiate Dictionary, the intransitive form of the verb "void" means "to eliminate solid or liquid waste from the body." We do not agree with this definition. "Void" in this sense is only applied to "liquid waste" (urine), never to "solid waste’ (feces).

Vomit: Vomit is the ejected matter from the stomach which occurs with symptoms of nausea. When reddish or coffee-ground colored it can represent serious internal bleeding.

von Recklinghausen’s disease: Hereditary disorder characterized by cafe-au-lait (coffee-with-milk spots on the skin and a tendency to develop nerve tumors) also known as neurofibromatosis.

VSD: Ventricular septal defect. Please see: Ventricular septal defect.

Vulva: The external genitalia of the female.