hepatitis B

The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

hepatitis B
A viral disease caused by the hepatitis B virus that is endemic worldwide, the areas of highest endemicity being China and Southeast Asia, sub-Saharan Africa, most Pacific islands, and the Amazon basin. The virus is shed in all body fluids by individuals with acute or chronic infections and by asymptomatic carriers, and is transmitted primarily by parenteral routes, such as by blood transfusion or by sharing of needles among drug users; oral transmission can occur but has low efficiency, and it can be spread by intimate personal contact, especially sexual contact, and by vertical transmission from mother to neonate. The incubation period averages about 90 days, with a range of 40 to 180 days, and the clinical course is more variable than in heptatitis A. In the prodromal phase there may be fever, malaise, anorexia, nausea, and vomiting, which decline with the onset of clinical jaundice, and urticaria, angioedema, arthritis, or, rarely, glomerulonephritis or a serum sickness-like syndrome may occur. Most patients recover completely and become HBsAg-negative in 3 to 4 months, but some remain chronic carriers or develop chronic active hepatitis or chronic persistent hepatitis. Massive hepatic necrosis (fulminant hepatitis) is an infrequent complication. In areas of high endemicity a relationship has been shown between hepatitis and virus infection, cirrhosis, and primary hepatocellular carcinoma, with the later being one of the most common neoplasms. Formerly called "inoculation hepatitis," "long-incubation hepatitis," "MS-2 hepatitis," "serum hepatitis," and "homologous serum hepatitis" or "jaundice."