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- Acquired immune deficiency syndrome (AIDS)
- A viral disease that destroys the body's ability to fight infections, leaving the body susceptible to many other diseases.
- Deviation from normal
- Active Immunity:
- See Immunity, active.
- A short-term, intense health effect.
- Acute Hepatitis C:
- Newly acquired symptomatic hepatitis C virus (HCV) infection.
- Adefovir dipivoxil:
- FDA approved antiviral drug, given by mouth, for treatment of persons with chronic hepatitis B.
- Adverse Events:
- Undesirable experiences occurring after immunization that may or may not be related to the vaccine.
- a protien made in the liver that assists in maintaining blood volume in the arteries and veins. If albumin drops to very low levels, fluid may leak into tissues from the blood vessels, resulting in edema or swelling.
- Alanine aminotransferase. An enzyme made by the liver; an increased level of ALT in the blood indicates liver inflammation.
- Alkaline phosphatase:
- elevated levels of this liver enzyme are not commonly seen with HBV, although modest elevations may occur with the development of cirrhosis.
- Alpha-fetoprotein (AFP):
- A substance produced by the fetus that is found in fetal serum, amniotic fluid, and the mother's bloodstream. Elevated levels of AFP may indicate that the baby has a neural tube defect such as spina bifida (incomplete closure of the spinal column) which can lead toparalysis of the lower limbs, repeated urinary tract infections, mental retardation or hydrocephalus ("water on the brain"); it is also a useful nonspecific tumor-associated antigen (tumor marker) that, when elevated, can indicate liver cancer.
- The process of explaining an entity or idea by examining it in terms of its various parts (e.g., a statistical technique for defining and segregating the causes of variability affecting a set of observations).
- A substance that fights bacteria.
- 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.
- Foreign substances (e.g. bacteria or viruses) in the body that are capable of causing disease. The presence of antigens in the body triggers an immune response, usually the production of antibodies.
- Anti-HBe (Hepatitis B e antibody):
- The corresponding antibody to hepatitis B e antigen. The presence indicates low levels of virus in the blood of an hepatitis B virus (HBV) infected person; its presence also can indicate a good response to the treatment of chronic hepatitis B.
- Literally "against-virus" — any medicine capable of destroying or weakening a virus.
- AST (aspartate aminotransferase):
- An enzyme produced in the liver. Elevated levels may indicate liver damage.
- Presenting no symptoms of disease.
- Autoimmune disease:
- A condition when the immune system mistakenly attacks itself, targeting the cells, tissues, and organs of a person's own body.
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- Tiny one-celled organisms present throughout the environment that require a microscope to be seen. While not all bacteria are harmful, some cause disease. Examples of bacterial disease include diphtheria, pertussis, tetanus, Haemophilus influenza and pneumococcus (pneumonia).
- BCG (Bacille Calmette Guerin):
- vaccine prepared from a live attenuated strain of tubercle bacilli and used to vaccinate people against tuberculosis.
- The manner in which one acts; the actions or reactions of individuals under specific circumstances.
(see high-risk behavior)
- Not recurrent or progressive; nonmalignant; of a mild type or character that does not threaten health or life.
- a yellow pigment formed when red blood cells break down. Bilirubin levels may rise when liver function is impaired, leading to the development of jaundice, a yellowing of the eyes and skin.
- examination of a sample of liver cells to confirm diagnosis of HBV and determine the extent of damage to the liver. Biopsy is normally an outpatient procedure where a small number of liver cells are removed under local anesthetic using a needle.
- Booster Dose:
- An additional dose of an immunizing agent to increase the protection afforded by the original series of injections.
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- A person or animal that harbors a specific infectious agent without visible symptoms of the disease. A carrier acts as a potential source of infection.
- cccDNA (HBV):
- covalently closed circular DNA, the key template in hepadnavirus replication. This molecule is highly stable, with multiple copies in the nucleus of an infected cell, where it remains despite antiviral treatment. Clearing cccDNA from the liver cell would theoretically rid the liver of HBV infection.
- Childhood Immunizations:
- A series of immunizations that are given toprevent diseases that pose a threat to children. The immunizations in the United States currently include: Hepatitis B, Diphtheria, Tetanus, Acellular Pertussis, Haemophilus Influenzae type b, Inactivated Polio, Pneumococcal Conjugate, Measles, Mumps, Rubella, Varicella, and Hepatitis A.
- Chronic Health Condition:
- A health related state that lasts for a long period of time (e.g. multiple sclerosis, asthma).
- Chronic Hepatitis B Virus Infection:
- The clinical definition for an individual for whom the hepatitis B surface antigen test is positive (indicates HBV in the blood and infectiousness) for more than six months; in the past, it was referred to as hepatitis B carrier.
- Chronic Hepatitis C Virus Infection:
- Liver inflammation in patients with chronic HCV infection; characterized by abnormal levels of liver enzymes.
- Centers for Disease Control and Prevention.
- Chronic Liver Disease:
- A disease of the liver of long duration.
- Enhanced chemiluminescence immunoassay; FDA licensed and approved laboratory screening test that detects HCV antibody.
- Irreversible scarring of the liver, due to ongoing damage, which may affect liver function. Cirrhosis can lead to liver failure and even death.
- Clotting Factors:
- proteins made in the liver that are important in maintaining normal blood clotting. Disruption in the blood's abililty to clot may indicate that the liver is not creating enough clotting factors. A severe shortage in clotting factors may indicate that a liver transplant is needed.
- The condition of an organism or individual cells being infected simultaneously by two different pathological microorganisms, such as infection with both HIV and hepatitis C virus (HCV).
- Combination Vaccine:
- Two or more vaccines combined and administered at once in order to reduce the number of shots given. For example, the MMR (measles, mumps, rubella) vaccine.
- Capable of spreading disease. Also known as infectious.
- One who has been recently exposed to an infectious agent.
- Capable of being transmitted from one person to another by contact or close proximity.
- To make unfit for use through the introduction of a substance that is harmful or injurious; to make impure or unclean.
- Any circumstance or symptom that makes a method of treatment inadvisable in a particular case.
- Controlled clinical trials:
- Trials in which the outcome of a group given one treatment is compared with the outcome of a group given no treatment or given a different treatment.
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- Symptomatic sickness, illness or loss of health.
- Killing of infectious agents outside the body by direct exposure to chemical or physical agents; high-level disinfection might kill all microorganisms with the exception of high numbers of bacterial spores; it requires extended exposure to ensure killing of most bacterial spores; it is achieved, after thorough detergent cleaning, by exposure to specific concentrations of certain disinfectants (e.g., 2% glutaraldehyde, 6% stabilized hydrogen peroxide and up to 1% peracetic acid) for at least 20 minutes; intermediate-level disinfection does not kill spores; it can be achieved by pasteurization (75 deg. C. [167 deg. F.] for 30 minutes) or by appropriate treatment with EPA-approved disinfectants.
- Decompensated Cirrhosis:
- a late-stage cirrhosis accompanied by abnormal blood tests and other complications. At this stage of the disease, evaluation for liver transplant becomes an option.
- Deoxyribonucleic acid; DNA molecules carry the genetic information necessary for the organization and functioning of most living cells and control the inheritance of characteristics.
- DNA Polymerase:
- an enzyme essential to the replication of HBV DNA.
- One who abandons treatment.
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- Enzyme immunoassay; an assay that uses an enzyme-bound antibody to detect antigen. The enzyme catalyzes a color reaction when exposed to substrate.
- The occurrence of disease within a specific geographical area or population that is in excess of what is normally expected.
- The study of the spread of diseases. Epidemiologists are often sent to investigate outbreaks.
- The continual, low-level presence of disease in a community.
- Relating to, or being within the small intestine.
- Proteins (or rarely, RNA) that catalyzes a chemical reaction; are produced by living cells and catalyze specific biochemical reactions at body temperatures.
- Coming in direct contact with an agent that might cause a disease or infectious process (e.g., exposure to HBV might result in hepatitis B disease).
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- False negative:
- Test result that indicates that an abnormality or disease is not present when, in fact, it is.
- False positive:
- Test result that indicates that an abnormality or disease is present when, in fact, it is not.
- Mode of transmission of an infectious agent from person toperson by putting something in the mouth that has been contaminated with the stool of an infected person.
- scar tissue developed as a result of chronic infection and inflammation. The presence of fibrosis usually means several years of active infection have taken place.
Fulminant - Occurring suddenly, with lightning-like rapidity, and with great intensity or severity.
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- Global Alliance for Vaccines and Immunizations.
- Genetic makeup of the virus that describes the ≥family≤ to which the specific virus belongs; there are at least 6 distinct HCV genotypes identified genotype 1 is the most common genotype seen in the United States.
- GGT (gamma-gutamyl transferase):
- a liver enzyme that may be elevated in patients with hepatitis.
Guillain-Barre syndrome - An inflammation of the nerves of unknown cause characterized especially by muscle weakness and paralysis.
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- A sex-linked hereditary blood defect that occurs almost exclusively in males and is characterized by delayed clotting of the blood and consequent difficulty in controlling hemorrhage even after minor injuries.
- The use of a machine to clean wastes from the blood after the kidneys have failed; the blood travels through tubes to a dialyzer, a machine that removes wastes and extra fluid; the cleaned blood then goes back into the body.
- An inflammation of the liver; the most common cause is infection with one of the five hepatitis viruses; hepatitis can also be caused by other viruses, bacteria, parasites and toxic reactions to drugs, alcohol and chemicals.
- Hepatitis A:
- A liver disease caused by the hepatitis A virus (HAV). HAV is a 27-nm agent classified as a picornovirus and does not cause a chronic (long-lasting) illness. The virus is transmitted through close intimate contact with an infected person or through ingestion of contaminated food or water.
- Hepatitis B:
- A liver disease caused by the Hepatitis B virus (HBV). HBV is found in the blood of infected persons and is most commonly transmitted through unprotected sex.
Hepatitis B Core Antibody (anti-HBc) - Appears at the onset of symptoms in acute hepatitis B and persists for life. The presence of anti-HBc indicates previous or ongoing infection with HBV.
- Hepatitis B e Antibody (HBeAb or anti-HBe):
- produced by the immune system temporarily during acute HBV infection or consistently during or after a burst in viral replication. Spontaneous conversion from e antigen to e antibody (a change known as seroconversion) is a predictor of long-term clearance of HBV in patients undergoing antiviral therapy.
- Hepatitis B e Antigen (HBeAg
- A secreted product of the nucleocapsid gene of HBV and is found in serum during acute and chronic hepatitis B. Its presence indicates that the virus is replicating and the infected individual is potentially infectious.
- Hepatitis B Immune Globulin (HBIG)
- A product available for prophylaxis against hepatitis B virus infection. HBIG is prepared from plasma containing high titers of anti-HBs and provides short-term protection (3 - 6 months).
- Hepatitis B Surface Antibody (anti-HBs):
- The presence of anti-HBs is generally interpreted as indicating recovery and immunity from HBV infection.
- Hepatitis B Surface Antigen (HBsAg):
- A serologic marker on the surface of HBV. It can be detected in high levels in serum during acute or chronic hepatitis. The body normally produces antibodies to surface antigen as part of the normal immune response to infection.
- Hepatitis B Vaccination:
- Having received hepatitis B vaccine; hepatitis B immunization indicates that the person who received hepatitis B vaccine has developed adequate hepatitis B surface antibody and is protected against HBV infection.
- Hepatitis B Virus DNA (deoxyribonucleic acid):
- controls the manufacture of the hepatitis B virus. Presence of HBV DNA indicates active viral replication, with high levels of HBV DNA correlated with high rates of replication. HBV DNA levels are used to determine response to antiviral therapy.
- Hepatitis C:
- 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, most commonly through injection drug use.
- Hepatitis C Virus RNA (ribonucleic acid):
- Fragments of the replicating hepatitis C virus (HCV). These can be detected using sophisticated testing to determine the level of hepatitis C virus present in the serum.
- Hepatitis D:
- A liver disease caused by Hepatitis Delta virus (HDV). HDV is a defective virus that needs HBV to exist. HDV is found in the blood of persons infected with the virus and is transmitted in much the same way as HBV is transmitted; however the case fatality rate with HDV infection is higher than with Hepatitis B.
- Hepatitis E:
- A disease of the liver caused by the Hepatitis E virus (HEV). HEV is transmitted in much the same way as HAV. Hepatitis E, however, does not often originate in the United States. Mortality is high among pregnant women who have hepatitis E.
- Hepatocellular Carcinoma (HCC):
- The most common primary malignant liver tumor.
- High-Risk Behavior:
- unsafe behaviors (e.g., sharing needles or drug paraphernalia; having multiple sex partners).
High-Risk Group: A group in the community with an elevated risk of disease.
- Human immunodeficiency virus.
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- Injection Drug User.
Igm anti-HBc - Detected at onset of acute hepatitis B and persists for 3 to 12 months if the disease resolves. In patients who develop chronic hepatitis B, IgM anti-HBc persists at low levels as long as viral replication persists.
- Immune Globulin (IG):
- Proteins found in the blood that function as antibodies that fight infection. Previously known as gamma globulin.
- Immune System:
- The complex system in the body responsible for fighting disease. Its primary function is to identify foreign substances in the body (bacteria, viruses, fungi or parasites) and develop a defense against them. This defense is known as the immune response. It involves production of protein molecules called antibodies to eliminate foreign organisms that invade the body.
- Protection against a disease. There are two types of immunity, passive and active. Immunity is indicated by the presence of antibodies in the blood and can usually be determined with a laboratory test. See active and passive immunity.
- Immunity, Active:
- Resistance developed in response to an antigen (infecting agent or vaccine) and usually characterized by the presence of antibody produced by the host.
Immunity, Passive: Immunity conferred by an antibody produced in another host. This type of immunity can be acquired naturally by an infant from its mother or artificially by administration of an antibody-containing preparation (antiserum or immune globulin).
- The process by which a person or animal becomes protected against a disease.
- Any condition in which the immune system functions in an abnormal or incomplete manner; such conditions are more frequent in the young, the elderly, and individuals undergoing extensive drug or radiation therapy.
- Producing immunity; capable of inducing an immune response; for example, hepatitis B vaccine produces a protective immune response in 90%-95% of young healthy adults.
- Preventing the spread of disease by providing physiological immunity.
- When the immune system is unable toprotect the body from disease. This condition can be caused by disease (like AIDS) or by certain drugs (like those used in chemotherapy). Individuals whose immune systems are compromised should not receive live, attenuated vaccines.
- 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.
- An invasion of an organism by a pathogen such as bacteria or viruses. Some infections lead to disease.
- Capable of spreading disease. Also known as communicable.
- Infectious Agents:
- Organisms capable of spreading disease (e.g. bacteria or viruses).
- A protein produced naturally by the cells of our bodies; interferon increases the resistance of surrounding cells to attacks by viruses; one type of interferon, alpha interferon, is effective against certain types of cancer and is used in the treatment of chronic hepatitis B and chronic hepatitis C; others might prove effective in treating autoimmune diseases.
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- Yellowing of the eyes and skin. This condition is often a symptom of viral hepatitis infection.
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- FDA approved antiviral drug, administered by mouth, for use in treating chronic hepatitis B.
- A large reddish-brown glandular organ located in the upper right portion of the abdominal cavity; secretes bile and functions in metabolism of protein and carbohydrate and fat; synthesizes substances involved in the clotting of the blood; synthesizes vitamin A; detoxifies poisonous substances and breaks down worn-out erythrocytes; the liver is capable of repairing itself in some instances, but a person must have some liver function to survive; liver damage caused by HCV infection is the primary cause for liver transplantation.
- Liver Enzymes:
- proteins that catalyze chemical reactions needed for bodily functions. Levels of certain enzymes, such as ALT and AST, are higher when the liver is injured, as they leak into the bloodstream when the cell is injured or destroyed.
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- A device or substance used to indicate or mark something; an identifying characteristic or trait that allows apparently similar materials or disease conditions to be differentiated; this term is often used when discussing blood tests; for example, the hepatitis B surface antigen test is a serologic marker for current infectiousness with hepatitis B virus.
- Tiny organisms (including viruses and bacteria) that can only be seen with a microscope.
- Morbidity and Mortality Weekly Report.
- Any departure, subjective or objective, from a state of physiological or psychological well-being.
- The number of deaths in a given time or place.
- Men who have sex with men.
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- National Institute of Health.
- Referring to an infection acquired by a patient while in a hospital.
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- Beginning of the disease.
- Any living thing. Organisms include humans, animals, plants, bacteria, protozoa, and fungi.
- Sudden appearance of a disease in a specific geographic area (e.g. neighborhood or community) or population (e.g. adolescents).
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- An epidemic occurring over a very large area.
- Passive Immunity:
- See Immunity, Passive.
- Any organism that lives in or on another organism without benefiting the host organism; commonly refers topathogens, most commonly in reference toprotozoans and helminths.
- A route through which medicine can be taken into the body or given in a manner other than through the digestive tract (e.g., intravenous or intramuscular injection).
- Bacteria, viruses, parasites, or fungi that can cause disease.
- Pegylated interferon:
- FDA approved antiviral drug for treatment of chronic hepatitis C in persons 18 years and older; pegylated interferon remains active in the bloodstream longer and at a more constant level than standard interferon and can be given less often than standard interferon; combination therapy using pegylated interferon and ribavirin is the treatment of choice for chronic hepatitis C.
- Passed through the skin.
- Passed through the mucosa, which is a lining of various organs (e.g., mucosal lining of the mouth).
- Pharmaceutical clinical trial:
- A carefully designed and executed investigation of the effects of a drug administered to human subjects; the goal is to define the clinical efficacy and pharmacological effects (toxicity, side effects, incompatibilities or interactions); the federal government requires strict testing of all new drugs before their approval for use as therapeutic agents.
- Post-exposure Prophylaxis (PEP)
- Prevention or treatment of disease after a possible exposure.
- The number of disease cases (new and existing) within a population at a given time.
- Prodromal phase:
- Pertaining to the initial stage of a disease; the interval between the earliest symptoms and the appearance symptoms.
- Measures designed topreserve health (as of an individual or of society) and prevent the spread of disease (e.g., HBIG and hepatitis B vaccine given to a baby born to an HBV infected mother is a prophylactic treatment toprevent perinatal HBV transmission).
- A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene that codes for the protein. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs; and each protein has unique functions. Examples are hormones, enzymes, and antibodies.
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- To isolate an individual who has or is suspected of having a disease, in order toprevent spreading the disease to others; alternatively, to isolate a person who does not have a disease during a disease outbreak, in order toprevent that person from catching the disease (this is called reverse isolation) . Quarantine can be voluntary or ordered by public health officials in times of emergency.
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- An oral antiviral medication, when combined with interferon improves the effectiveness of interferon in treating chronic hepatitis C; combination therapy that includes pegylated interferon and ribavirin is the current treatment of choice for chronic hepatitis C.
- Recombinant immunoblot assay; FDA licensed and approved supplemental laboratory test that detects antibodies against HCV and is used to verify a positive anti-HCV by EIA.
- The likelihood that an individual will experience a certain event.
- Ribonucleic acid; chemical found in the nucleus and cytoplasm of cells; plays an important role in protein synthesis and other chemical activities of the cell; the structure of RNA is similar to that of DNA; there are several classes of RNA molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each serving a different purpose.
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- Development of antibodies in the blood of an individual who previously did not have detectable antibodies.
- The rate at which a given population tests positive for certain diseases or conditions at a certain point in time.
- Measurement of antibodies, and other immunological properties, in the blood serum.
- An antigenic property of a cell (e.g., bacteria, RBC) or virus identified by serological methods.
- Side Effect:
- Undesirable reaction resulting from immunization or other medication, treatment, etc.
- Safe Injection Global Network; SIGN is a voluntary coalition of stakeholders aiming to achieve safe and appropriate use of injections throughout the world; the Essential Health Technologies (EHT) department of the World Health Organization (WHO) provides the secretariat for the network.
- A portion or quantity of material for use in testing, examination or study (e.g., stool specimen).
- occurring occasionally or in scattered instances.
- Sexually Transmitted Disease.
- A new infection caused by an organism different from that which caused the initial infection; the microbe responsible is usually resistant to the treatment given for the initial infection; for example, this term is used when a person with chronic hepatitis B contracts a superinfection with hepatitis Delta virus.
- The systematic collection, analysis, interpretation, and dissemination of health data on an ongoing basis, to gain knowledge of the pattern of disease occurrence and potential in a community, in order to control and prevent disease in the community.
- Unprotected against a certain disease.
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- A mercury-containing preservative used in some vaccines and other products since the 1930's. No harmful effects have been reported from thimerosal at doses used in vaccines, except for minor reactions like redness and swelling at the injection site. However, in July 1999, the Public Health Service (PHS) agencies, the American Academy of Pediatrics (AAP), and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure. Today, all routinely recommended pediatric vaccines manufactured for the U.S. market contain no thimerosal or only trace amounts.
- The concentration of a substance in solution as determined by titration; antibody concentrations are measured this way; titers are often listed as dilutions, like 1:20, the higher the dilution the greater the amount that was originally present.
- An incident in which an infectious agent is transmitted.
Twinrix: Combined hepatitis A and hepatitis B vaccine manufactured by Glaxo-SmithKline.
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- United Nations International Children's Emergency Fund; an organization works for children's rights, their survival, development and protection.
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- Injection of a killed or weakened infectious organism in order toprevent the disease.
- A product that produces immunity therefore protecting the body from the disease. Vaccines are administered through needle injections, by mouth and by aerosol.
- Vaccine Schedule:
- A chart or plan of vaccinations that are recommended for specific ages and/or circumstances.
- Viral load:
- Measurement of the actual amount of virus in the bloodstream (e.g., HBV and HCV viral load).
- The presence of viruses in the bloodstream
- A tiny organism that multiples within cells and causes disease such as chickenpox, measles, mumps, rubella, pertussis and hepatitis. Viruses are not affected by antibiotics, the drugs used to kill bacteria.
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- World Health Organization.
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Based on information published by the Centers for Disease Control.
Division of Viral Hepatitis
Centers for Disease Control and Prevention
National Center for Infectious Diseases
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