Acute Infection: A suddenly occurring infection. It can end quickly or turn into a chronic (prolonged) infection, as often happens in hepatitis C [ed. note: or hepatitis B].

Alanine aminotransferase (ALT): An enzyme released from liver cells. A blood test that reveals ALT levels above normal may indicate liver damage.

Amino acids: Organic compounds that link together to build the proteins our bodies are made of.

Antibody: A protein molecule produced by cells of the immune system in response to a foreign body, such as a virus or bacteria. Antibodies circulate in the blood to protect against infection.

Anti-HBs (hepatitis B surface antibody): The antibody formed in response to the surface protein of the hepatitis B virus antigen (HBsAg). This antibody provides protective immunity against hepatitis B.

Anti-HCV (antibody to hepatitis C virus): The antibody directed against the hepatitis C virus (HCV). Its presence in the bloodstream often indicates HCV infection. This antibody has not been shown to protect people against hepatitis C.

Antigen: A foreign substance that the body's immune system identifies as potentially harmful, resulting in the production of antibodies to fight it. A virus protein is considered an antigen.

Ascites: Fluid, within the abdomen (belly), sometimes caused by cirrhosis.

Aspartate aminotransferase (AST): An enzyme released from liver cells. A blood test that reveals AST levels above normal may indicate liver damage.

Assay: A test or analysis.

Asymptomatic: Without signs of illness. Many patients with hepatitis C do not show signs of illness and are considered asymptomatic.

bDNA (branched DNA) assay: One of the two tests that reveal the presence in the bloodstream of minute quantities of DNA and RNA, such as RNA fragments from hepatitis C virus.

Biochemicals: Chemicals from which living organisms are made.

Bioengineering: Use of engineering principles to solve biomedical problems, such as creating chemicals or drugs that do not naturally occur. Also known as "genetic engineering."

Blood-borne substances: Those substances that are present in the blood and are carried by it throughout the body. Blood-borne substances, such as viruses, can be passed on to others through blood transfusions, needle-sharing, and even sharing a toothbrush.

Carcinoma: Any of several types of cancer.

Carrier: A person, generally in apparently good health, who has been infected with an organism and is capable of infecting and causing disease in others. Individuals persistently infected with hepatitis B and C are considered "carriers."

Centers for Disease Control and Prevention (CDC): This federal organization is concerned with the prevention and control of communicable diseases, conducts extensive research, and provides information about public health topics.

Chromosomes: Thread-like structures in the nucleus of an animal or plant cell that carry the genetic information that determines the characteristics of the particular organism.

Chronic infection: An infection that lasts for a long time or that returns after it had seemed to be cured. A patient with chronic hepatitis C is anyone with abnormally high ALT levels for more than 6 months.

Cirrhosis of the liver: The result of long-standing inflammation and damage in the liver, such as may be caused by a hepatitis C infection or alcohol. It is characterized by excess formation of scar tissue, also called fibrosis, and results in the loss of liver cells and increased resistance to the flow of blood through the liver.

Clinical trials: Carefully controlled tests that are conducted in humans to learn the effectiveness and safety of new medical products (such as all new drugs) and techniques.

Complications: New medical problems that arise while treating existing ones. Concomitant event: An event, such as a medical condition, that occurs at the same time as another.

Contagious disease: Disease spread by direct or indirect contact.

Course of infection: The stages an infection goes through from the appearance of the first problem, through treatment, to its conclusion.

Cytokines: Hormone-like proteins that are secreted by many different types of cells. Cytokines regulate the intensity and duration of immune responses.

Cytotoxic substances: Substances that can destroy cells.

DNA (deoxyribonucleic acid): A component in the cells of all living matter that carries hereditary genetic information. DNA helps determine what an organism will be-a virus, a human-as it develops to maturity.

ELISA (enzyme-linked immunosorbent assay): This is a test that provides information on the presence or amount of antibodies in the bloodstream. This test is sometimes referred to as an "EIA."

Encephalopathy: A variety of brain function abnormalities experienced by some patients with liver disease. These most commonly include confusion, disorientation, and insomnia, and may progress to coma.

Enzymes: Naturally occurring chemical substances in the human body that help a chemical reaction take place.

Enzyme immunoassay (EIA): A test that provides information on the presence or amount of antibodies in the bloodstream. This test is sometimes referred to as an "ELISA."

Epidemiology: Investigation of the causes of, and ways to control, diseases.

False-positive: A test result which mistakenly gives a positive reading.

Flavivirus: A group of related viruses, including the viruses that cause yellow fever, St. Louis encephalitis, and hepatitis C.

Follow-up: Checking on results periodically after treatment has been prescribed.

Food and Drug Administration (FDA): A federal organization, charged with protecting the public health, that establishes safety and effectiveness guidelines and rules for healthcare products, such as the drugs that are used to treat hepatitis.

Gastroenterology: The branch of medicine that focuses on the function and disorders of the esophagus, stomach, pancreas, intestines, and liver.

Genotype: A pattern of genetic information that is unique to a group of organisms or viruses. Doctors may determine the genotype of hepatitis C to help decide the best treatment.

HBsAg (hepatitis B surface antigen): A protein of the hepatitis B virus (HBV) that may be detected in blood and is an indicator of infection.

HCV RNA (hepatitis C virus ribonucleic acid): Fragments of the replicating hepatitis C virus (HCV). These can be detected using sophisticated testing (see: "bDNA assay" and "PCR") to determine the level of hepatitis C virus present in the serum.

Hepatic: Related to the liver.

Hepatitis: Inflammation of the liver caused by infection or toxic agents. There are several types:

Hepatitis A: Formerly called infectious hepatitis, hepatitis A is caused by the hepatitis A virus (HAV). It is an acute infection and does not progress to chronic hepatitis or cirrhosis. Most patients recover completely within 6 to 10 weeks. Hepatitis A is spread mainly via feces and contaminated food and water.

Hepatitis B: Formerly called serum hepatitis, it is caused by the hepatitis B virus (HBV). About 10% of cases progress to chronic hepatitis. [ed. note: If an infant is infected vertically, he/she has a 90% chance of progressing to chronic HBV] It is spread primarily through intravenous drug use, intimate contact with infected individuals, and exposure to infected body fluids. A vaccine against the hepatitis B virus is available.

Hepatitis C: A form of hepatitis that was previously known as non-A, non-B hepatitis and is caused by the hepatitis C virus (HCV). The Centers for Disease Control estimates 150,000 new cases each year, 6% to 10% of which are transfusion related. Of patients diagnosed with hepatitis C, 40% have no identified risk factors. Fifty percent of patients with recent hepatitis C infection develop chronic hepatitis C. Cirrhosis may develop in 20% of patients with chronic hepatitis C.

Hepatitis D: Also called delta hepatitis, hepatitis D is caused by the hepatitis D virus (HDV). HDV can only infect patients who already carry HBV. Hepatitis D infection is rare in the United States. It occurs primarily in recipients of multiple blood transfusions, including patients with hemophilia or undergoing renal dialysis, and among those who share contaminated needles.

Hepatitis E: Also referred to as enterically transmitted non-A, non-B hepatitis, hepatitis E is caused by a waterborne virus (HEV). It occurs primarily in developing countries and rarely occurs in the United States. Hepatitis E infection results in an acute infection much like hepatitis A. It does not cause chronic infection. It is spread by fecal contamination in water.

Hepatocellular carcinoma (hepatoma): A malignant tumor of the liver. Some types of chronic viral hepatitis (B and C) may place patients at some degree of risk (usually slight) for developing hepatocellular carcinoma.

Hepatocyte: A liver cell.

Hepatologist: A doctor who specializes in the study and treatment of liver disease.

Hepatology: The branch of medicine that focuses on diseases of the liver.

Histology: Sometimes called microscopic anatomy, histology focuses on the relationships of the minute structures of cells, tissue, and organs to their functions.

Immune system: The body's defense against invasion by bacteria, viruses, fungi, parasites, and malignant cells.

Immunology: The branch of medicine that focuses on the immune system, immunity, and allergy.

Infection: The results of the presence of harmful microorganisms in the body. Infections can be acute (sudden) or chronic (prolonged).

Inflammation: A condition caused by injury or abnormal stimulation by a physical, chemical, or biologic agent, and typified by redness, pain, heat, and swelling.

Injection: Using a needle to administer drugs or nutrients into the body in any of several ways, including:

Intramuscular: into muscle tissue.

Intravenous: into a vein.

Subcutaneous: beneath the skin.

Interferon: Protein that is in the body to protect against infection. Many different cells, including liver cells, produce natural interferon. Interferon also can be produced artificially through biotechnology.

Intravenous drug abuse (IVDA): Acquiring an addiction to narcotic-type drugs that require intravenous administration. The intravenous use and abuse of recreational and other illegal drugs is a common route of transmission for hepatitis C infection. [ed. note: This is also a common route for HBV infection]

Investigational drug: A new drug that is undergoing clinical trials to prove its effectiveness and safety.

Jaundice: A condition characterized by yellowness of the skin and eyes. Jaundice is a symptom of many disorders, including: obstruction of bile passageways by a gallstone; disease of the liver due to viral infection, alcoholism, or poisons; or breakdown of red blood cells.

Liver: The largest glandular organ in the body, the liver has many functions that include, but are not limited to: the production of protein and cholesterol, the production of bile, the storage of sugar in the form of glycogen, and the breakdown of carbohydrates, fats, and proteins. The liver also breaks down and excretes many medications.

Liver biopsy: The removal of a small piece of tissue from the liver using a special needle. The tissue is examined under a microscope to look for the presence of liver damage or inflammation.

Lymphocyte: A white blood cell that is part of the immune system. Lymphocytes help defend against infections.

Medical evaluation: Medical assessment of a patient's condition.

Medical history: A record of all the medical events in a person's life.

Natural killer (NK) cells: Components of a person's immune system that attack and destroy virus-infected cells.

Necrosis: The death of one or more cells, or of a portion of tissue or organ, such as the liver. For example, the damage caused by a chronic hepatitis virus infection.

Needle-stick: Accidental puncture of the skin while handling hypodermic needles. This is most common among healthcare providers such as physicians, nurses, and many hospital clinical care staff.

Non-A, non-B hepatitis: The term used until the late 1980s (before improved testing methods were developed) to identify all forms of hepatitis other than A and B.

Nonresponders: Patients who do not respond to therapy within a specified time frame.

Nosocomial infection: A new infection acquired during a patient's treatment in a hospital. An example could be a person who enters a hospital for a blood transfusion or organ transplant and inadvertently acquires an infection.

Parenteral: Introduction of a substance (such as a drug or nutrient) into the body through any route other than by mouth or suppository. Parenteral injections can be intravenous (into a vein), subcutaneous (beneath the skin), or intramuscular (within a muscle).

Pathologist: A physician who practices, evaluates, or supervises diagnostic tests, and who conducts experiments or other investigations to determine the causes or nature of diseases.

Patient compliance: Correctly following all the instructions about a course of therapy as directed by the physician and other healthcare providers.

PCR (polymerase chain reaction): A scientific method of detecting the presence in the bloodstream of minute quantities of DNA and RNA, such as RNA fragments from the hepatitis C virus.

Percutaneous: Passage or absorption of substances into the body through unbroken skin.

Perinatal transmission: Transmission of an infectious disease, such as hepatitis C, from mother to infant. It can happen in the uterus, or during or after birth.

Persistent: A disease or other medical condition that returns or continues over time.

Platelets: Circulating cells derived from the bone marrow and essential for blood coagulation (clotting).

Posttransfusion hepatitis: Hepatitis that occurs following a blood transfusion. This is now rare in the United States due to careful blood screening procedures.

Promiscuity: Having multiple partners in sexual relations.

Protein: A substance made of a string of amino acids. Proteins are the "building blocks" of the human body.

Prothrombin time: A laboratory measure of blood coagulation that is dependent on liver production of clotting factors. An indirect test of liver function.

Protocol: A step-by-step procedure followed to achieve an objective, such as the strictly followed methods used in clinical trials for new drugs.

Quasispecies: One or more subpopulations of a virus occurring in a single individual.

Recombinant DNA: Genetic material that has been altered and recombined through insertion of new DNA sequences using bioengineering. Many drugs are now produced using recombinant DNA methods.

Reconstitution: Adding liquid to a powder. Often injectable drugs are provided as a dry powder, and liquid must be added to the powder before it can be used.

Recreational drugs: Illegal drugs, such as marijuana, cocaine, and heroin that are used by people addicted to the drugs, or, if not addicted, who feel the effects of the drugs outweigh the risk factors associated with them.

Relapse: Return of disease symptoms after the disease was thought to be cured.

Remission: Partial or complete disappearance-or a lessening of the severity-of the symptoms of a disease. Remission may happen on its own or occur as a result of medical treatment.

Retreatment: Starting treatment again after the patient has suffered a relapse or has not responded to treatment the first time.

RIBA (recombinant immunoblot assay): A test that provides detailed information on the level of HCV antibodies in the bloodstream.

Risk factors: Certain behaviors (such as intravenous drug use or transfusions) linked to the development of an infection such as hepatitis C.

RNA (ribonucleic acid): Molecules, found in all cells, that translate DNA genetic information into proteins.

Route of transmission: The way or method by which a disease enters the body.

Screening: With blood donors, screening involves analyzing their blood for certain diseases (such as HCV, HBV, AIDS) before accepting it.

Self-administration: Therapy, such as injections, that patients give to themselves, instead of having it done for them by a physician or other healthcare providers.

Serology: A branch of medical testing that focuses on serum, particularly immune factors in serum.

Seronegative: When the suspected substance being searched for, such as hepatitis C virus, does not show up in a blood test.

Seropositive: When the suspected substance being searched for, such as hepatitis C virus, does show up in a blood test.

Seroprevalence: The frequency of a seropositive substance in a group of people.

Serotype: A subdivision of a species or subspecies on the basis of antigenic characteristics in serum.

Serum: The fluid portion of blood.

Sexual history: A record of all the sexual relations in a person's life.

Spleen: An organ located in the left upper abdomen that removes old red blood cells and other blood cells from circulation. The spleen can enlarge in a person who has cirrhosis.

STD(sexually transmitted disease): A disease that is transmitted through sexual contact.

Sustained response: A response to therapy that continues over a long time period. An example would be a patient who is successfully treated for hepatitis C, and remains free of the hepatitis C virus for 6 months after treatment has ended.

Symptom: A noticeable change in the body or its functions that indicates the presence of a disease.

T cells: A type of white blood cells that are involved in rejecting foreign tissue, regulating immunity, and controlling the production of antibodies to fight infection.

Therapy: Treatment of a disease.

Transaminases: An older term for the ALT and AST aminotransferases.

Transfusion: The introduction of whole blood or components of blood (such as plasma, platelets) from one person-or from pooled material or sources-into the bloodstream of another.

Transmission: Passing an infection or disease from one person to another.

Transplantation: Implanting tissue or an organ taken from one person into another person.

True-positive: A test result that accurately gives a positive reading.

Vaccine: A biological preparation introduced into the body to cause the production of antibodies that provide artificial immunity to a specific disease, such as hepatitis A.

Variceal bleeding: Bleeding from abnormal blood vessels in the esophagus (the tube that carries food from the mouth to the stomach). This may occur in patients with cirrhosis.

Viral hepatitis: A form of hepatitis caused by one of the hepatitis viruses (HAV, HBV, HCV, HDV, or HEV).

Viral load: The measurement of the amount of a given virus in the bloodstream.

Viremia: The presence of a given virus in the bloodstream.

Virus: A tiny organism-smaller than a bacterium-that can invade the body and cause disease. Hepatitis A, B, C, D, and E are caused by viruses.

Western blot assay: A test used in protein analysis.

White blood cells (WBCs): A group of cells originating in the bone marrow and essential for immune defense.

Amgen, with the help of Donald M. Jensen, MD, created a glossary of terms for understanding hepatitis. For more information, you may contact Amgen at:
Amgen Inc.
1840 DeHavilland Drive
Thousand Oaks, CA


Important disclaimer: The information on pkids.org is for educational purposes only and should not be considered to be medical advice. It is not meant to replace the advice of the physician who cares for your child. All medical advice and information should be considered to be incomplete without a physical exam, which is not possible without a visit to your doctor.

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