الفهرس 
Review of Literature
The hepntitis virusesOnly 14 pages are availabe for public view
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Abstract
epatitis B is a global health problem, particularly in the developing countries. It is estimated that more than 300 million carriers of hepatitis B surface antigen (HBsAg) are present worldwide. Worldwide, hepatitis B is probably the most common cause of acute and chronic liver disease and hepatocellular carcinoma (Hoofnagle, 1981). Chronic hepatitis B virus (HBV) infection is particularly important, because these carriers are not only reservoirs of HBV, but also frequent victim of chronic liver disease (Viola et al., 1981). In tropical Africa everyone is infected with HBV during childhood, and 20% of children become chronic carriers (Tomatis et al., 1990). Hepatitis B is a round, double-shelled DNA containing virus, with diameter of 42 nm. It is classified as a hepandavirus (type 1) (Maureen, 1996).
In Egypt, recent surveys indicated the hepatitis carriers (HBsAg +ve) range between 5 - 10% of the general population according to the age (Sherif et al., 1985). Therefore around 5 million Egyptions who are HBV carriers. The need for a preventive measure against such infection of utmost importance vaccination against HBV has proved effective in preventing the transmission of the disease.