Immunizations and Antibiotics for Overseas Travel Glossary of Medical Terms

These are medical definitions of medical terms from the MedTerms.com medical dictionary that appear in the Immunizations and Antibiotics for Overseas Travel article.

Aspirin: A good example of a tradename that entered into the language, Aspirin was once the Bayer trademark for acetylsalicylic acid .
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Bacteria: Single-celled microorganisms which can exist either as independent (free-living) organisms or as parasites (dependent upon another organism for life).
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Bacterial: Of or pertaining to bacteria . For example, a bacterial lung infection .
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Bicarbonate: In medicine, bicarbonate usually refers to bicarbonate of soda (sodium bicarbonate, baking soda) white powder that is common ingredient in antacids. Also, the bicarbonate level is an indirect measure of the acidity of the blood that is determined when electrolytes are tested. The normal serum range for bicarbonate is 22-30 mmol/L.
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Breastfeeding: Feeding a child human breast milk . According to the American Academy of Pediatrics , human breast milk is preferred for all infants. This includes even premature and sick babies, with rare exceptions. It is the food least likely to cause allergic reactions; it is inexpensive; it is readily available at any hour of the day or night; babies accept the taste readily; and the antibodies in breast milk can help a baby resist infections.
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Centers for Disease Control and Prevention: The US agency charged with tracking and investigating public health trends. The stated mission of the Centers for Disease Control and Prevention, commonly called the CDC, is "To promote health and quality of life by preventing and controlling disease, injury, and disability."
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Chickenpox: A highly infectious viral disease also known medically as varicella -- in many countries, this disease is always called "varicella" -- that causes a blister-like rash, itching, fatigue and fever. The rash crops up first on the face and trunk and can spread over the entire body resulting in 250 to 500 itchy blisters.


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Chloride: The major anion (negatively charged substance) in the blood and extracellular fluid (the body fluid that lies outside cells). Blood and other body fluids have almost the same concentration of chloride ion as sea water. The balance of chloride ion (Cl-) is closely regulated by the body.
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Cholera : A devastating and sometimes lethal disease with intense vomiting and profuse watery diarrhea leading to dehydration which, unless immediately treated, may be fatal.
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Diarrhea : A familiar phenomenon with unusually frequent or unusually liquid bowel movements, excessive watery evacuations of fecal material. The opposite of constipation . The word "diarrhea" with its odd spelling is a near steal from the Greek "diarrhoia" meaning "a flowing through." Plato and Aristotle may have had diarrhoia while today we have diarrhea. There are myriad infectious and noninfectious causes of diarrhea.
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Diphtheria: An acute infectious disease that typically strikes the upper respiratory tract including the throat. It is caused by infection with the bacteria Corynebacterium diphtheriae. Symptoms include sore throat and mild fever at first. As the disease progresses, a membranous substance forms in the throat that makes it difficult to breathe and swallow.
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Encephalitis: Inflammation of the brain. Encephalitis occurs, for example, in 1 in 1,000 cases of measles . It may start (up to 3 weeks) after onset of the measles rash and present with high fever , convulsions, and coma. It usually runs a blessedly short course with full recovery within a week. Or it may eventuate in central nervous system impairment or death.
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Endemic: Present in a community at all times but in relatively low frequency. Something that is endemic is typically restricted or peculiar to a locality or region.
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Fever : Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered to have a significant fever until the temperature is above 100.4 degrees F (38 degrees C.).
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Glucose: The simple sugar (monosaccharide) that serves as the chief source of energy in the body. Glucose is the principal sugar the body makes. The body makes glucose from proteins, fats and, in largest part, carbohydrates. Glucose is carried to each cell through the bloodstream. Cells, however, cannot use glucose without the help of insulin . Glucose is also known as dextrose.
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Hepatitis: Inflammation of the liver from any cause.
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Hepatitis A: Inflammation of the liver caused by the hepatitis A virus (HAV). HAV is usually transmitted from person to person by food or drink that has been contaminated with the stool of a person with hepatitis A. This type of transmission is called "fecal-oral." The virus is more easily spread in areas where there are poor sanitary conditions or where good personal hygiene is not observed. In 2003 there were hepatitis A outbreaks in the US associated with eating raw or lightly cooked green onions (scallions). Casual contact, as in a school, office, or another work setting, does not spread the virus.
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Hepatitis B: Inflammation of the liver due to the hepatitis B virus (HBV), once thought to be passed only through blood products. It is now known that hepatitis B can also be transmitted via needle sticks, body piercing and tattooing using un sterilized instruments, the dialysis process, sexual and even less intimate close contact, and childbirth. Symptoms include fatigue, jaundice , nausea, vomiting, dark urine, light stools. Diagnosis is by blood test. Treatment is via anti-viral drugs and/or hepatitis B immunoglobulin (HBIG).
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Immunity: The condition of being immune. Immunity can be innate (for example, humans are innately immune to canine distemper) or conferred by a previous infection or immunization.
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Immunization: Vaccination. 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 immunize against bacterial diseases, it is generally possible to use only 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 Immunizations (in the plural) and Immunization of a specific type (such Immunization, Polio).
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Immunoglobulin: A protein produced by plasma cells and lymphocytes and characteristic of these types of cells. Immunoglobulins play an essential role in the body's immune system. They attach to foreign substances, such as bacteria, and assist in destroying them. Immunoglobulin is abbreviated Ig. The classes of immunoglobulins are termed immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM), immunoglobulin D (IgD) and immunoglobulin E (IgE).
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Incidence: The frequency with which something, such as a disease, appears in a particular population or area. In disease epidemiology, the incidence is the number of newly diagnosed cases during a specific time period. The incidence is distinct from the prevalence which refers to the number of cases alive on a certain date.
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Infection: The growth of a parasitic organism within the body. (A parasitic organism is one that lives on or in another organism and draws its nourishment therefrom.) A person with an infection has another organism (a "germ") growing within him, drawing its nourishment from the person.
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Influenza: The flu is caused by viruses that infect the respiratory tract which are divided into three types, designated A, B, and C. Most people who get the flu recover completely in 1 to 2 weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia . Much of the illness and death caused by influenza can be prevented by annual influenza vaccination.
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Kidney: One of a pair of organs located in the right and left side of the abdomen which clear "poisons" from the blood, regulate acid concentration and maintain water balance in the body by excreting urine. The kidneys are part of the urinary tract. The urine then passes through connecting tubes called "ureters" into the bladder. The bladder stores the urine until it is released during urination.


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Liter: A metric measure of capacity that, by definition, is equal to the volume of a kilogram of water at 4 degrees centigrade and at standard atmospheric pressure of 760 millimeters of mercury.

  • Metric equivalents -- There are 1000 cubic centimeters or 1 cubic decimeter in 1 liter.
  • U.S. equivalent -- A liter is a little more than a quart (1.057 U.S. liquid quarts).

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Malaria : An infectious disease caused by protozoan parasites from the Plasmodium family that can be transmitted by the sting of the Anopheles mosquito or by a contaminated needle or transfusion. Falciparum malaria is the most deadly type.
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Measles : An acute and highly contagious viral disease characterized by fever , runny nose, cough, red eyes, and a spreading skin rash . Measles , also known as rubeola, is a potentially disastrous disease. It can be complicated by ear infections, pneumonia , encephalitis (which can cause convulsions, mental retardation, and even death), the sudden onset of low blood platelet levels with severe bleeding (acute thrombocytopenic purpura), or a chronic brain disease that occurs months to years after an attack of measles (subacute sclerosing panencephalitis).
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Medical school: A school with a curriculum leading to a medical degree. The mission of every medical school includes medical teaching, research, and patient care. All medical schools share the goal of preparing students in the art and science of medicine, and providing them with the background necessary to enter the period of graduate medical education. The years of medical school preceding graduate medical education are typically divided into a preclinical phase and a clinical phase.
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Meningococcus: A type of bacteria now formally known as Neisseria meningitidis, which is responsible for a number of meningococcal diseases including epidemic bacterial meningitis, an inflammation of the coverings of the brain and spinal cord.
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Methotrexate : A drug that acts as an antimetabolite and specifically as a folic acid antagonist that inhibits the synthesis of DNA , RNA , and protein .
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Mumps : An acute (sudden, shortlived) viral illness that usually presents with inflammation of the salivary glands, particularly the parotid glands. A child with mumps often looks like a chipmunk with a full mouth due to the swelling of the parotids (the salivary glands near the ears).
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Oral rehydration therapy: The administration of special fluids by mouth treat dehydration . Abbreviated ORT. See also: Oral rehydration salts.
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Passive immunity: Immunity produced by the transfer to one person of antibodies that were produced by another person. Protection from passive immunity diminishes in a relatively short time, usually a few weeks or months. For example, antibodies passed from the mother to the baby before birth confer passive immunity to the baby for the first 4-6 months of life. See also, by contrast: Active immunity .
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Pertussis : Whooping cough, a communicable, potentially deadly illness characterized by fits of coughing followed by a noisy, "whooping" indrawn breath. It is caused by the bacteria Bordetella pertussis . The illness is most likely to affect young children, but sometimes appears in teenagers and adults, even those who have been previously immunized. Immunization with DPT (diphtheria-pertussis-tetanus) vaccine provides protection, although that immunity may wear off with age. When teenagers and adults get pertussis, it appears first as coughing spasms, and then a stubborn dry cough lasting up to eight weeks.
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Pharmacy: A location where prescription drugs are sold. A pharmacy is, by law, constantly supervised by a licensed pharmacist.
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Plague: The plague is an infectious disease due to a bacteria called Yersinia pestis .
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Polio: Abbreviation for poliomyelitis, an acute and sometimes devastating disease caused by a virus. Man is the only natural host for polio virus. The virus enters the mouth and multiplies in lymphoid tissues in the throat and intestine. Small numbers of virus enter the blood and go to other sites where the virus multiplies more extensively. Another round of viremia (virus in the bloodstream) leads to invasion of the central nervous system (CNS), the spinal cord and brain, the target sites struck by the virus.
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Potassium: The major positive ion (cation) found inside of cells. The chemical notation for potassium is K+.
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Pregnant: The state of carrying a developing fetus within the body.
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Quarantine: The period of isolation decreed to control the spread of infectious disease. Before the era of antibiotics, quarantine was one of the few available means for halting the spread of infectious diseases. It is still employed as needed. The list of quarantinable diseases in the US includes cholera , diphtheria , infectious tuberculosis , plague , smallpox , yellow fever , and viral hemorrhagic fevers (such as Marburg, Ebola and Congo-Crimean disease). In 2003, SARS (severe acute respiratory syndrome) was added as a quarantinable disease.
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Rabies : A potentially fatal viral infection that attacks the central nervous system .
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Rehydration: The process of restoring lost water to the body tissues and fluids. Prompt rehydration is imperative whenever dehydration occurs, from diarrhea , exposure, lack of drinking water, or medication use. Rehydration can be by the oral route or by the intravenous administration of fluids.
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Resistance: Opposition to something, or the ability to withstand it. For example, some forms of staphylococcus are resistant to treatment with antibiotics.
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Sodium: The major positive ion (cation) in fluid outside of cells. The chemical notation for sodium is Na+. When combined with chloride, the resulting substance is table salt.
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Tetanus : An often fatal infectious disease caused by the bacteria Clostridium tetani (C. tetani) which usually enters the body through a puncture, cut, or open wound. Tetanus is characterized by profoundly painful spasms of muscles, including "locking" of the jaw so that the mouth cannot open (lockjaw). C. tetani releases a toxin that affects the motor nerves, (the nerves which stimulate the muscles).
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Therapy: The treatment of disease .
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Tongue: The tongue is a strong muscle anchored to the floor of the mouth. It is covered by the lingual membrane which has special areas to detect tastes.
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Traveler's diarrhea: Diarrhea that results from infections acquired while traveling to another country. Among the causes of traveler's diarrhea are enterotoxigenic E. coli and a variety of viruses.
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Tuberculosis : A highly contagious infection caused by the bacterium called Mycobacterium tuberculosis. Abbreviated TB. Tubercles (tiny lumps) are a characteristic finding in TB. Diagnosis may be made by skin test, which if positive should will be followed by a chest X-ray to determine the status (active or dormant) of the infection. Tuberculosis is more common in people with immune system problems, such as AIDS, than in the general population. Treatment of active tuberculosis is mandatory by law in the US, and should be available at no cost to the patient through the public health system. It involves a course of antibiotics and vitamins that lasts about six months. It is important to finish the entire treatment, both to prevent reoccurrence and to prevent the development of antibiotic-resistant tuberculosis. Most patients with tuberculosis do not need to be quarantined, but it is sometimes necessary.
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Typhoid: See: Typhoid fever .
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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).
See the entire definition of Vaccination

Vaccines: Microbial preparations of killed or modified microorganisms that can stimulate an immune response in the body to prevent future infection with similar microorganisms. These preparations are usually delivered by injection.
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Viral: Of or pertaining to a virus. For example, "My daughter has a viral rash ."
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World Health Organization: An agency of the United Nations established in 1948 to further international cooperation in improving health conditions. Although the World Health Organization inherited specific tasks relating to epidemic control, quarantine measures, and drug standardization from the Health Organization of the League of Nations (that was set up in 1923) and from the International Office of Public Health at Paris (established in 1909), the World Health Organization was given a broad mandate under its constitution to promote the attainment of "the highest possible level of health" by all people. WHO defines health positively as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity."
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Yellow fever: An acute systemic (bodywide) illness caused by a virus called a Flavivirus . In severe cases, the viral infection causes a high fever, bleeding into the skin, and necrosis (death) of cells in the kidney and liver. The damage done to the liver from the virus results in severe jaundice which yellows the skin. Hence, the "yellow" in "yellow fever."
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Yellow fever vaccination: A live attenuated (weakened) viral vaccine that is recommended for people traveling to or living in tropical areas in the Americas and Africa where yellow fever occurs. Because it is a live vaccine, it should not be given to infants or people with immune-system problems.
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