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Abstract
Hepatitis B virus (HBV) infection is one of the major health problems in the world with an estimation of 350 million people chronically infected. It is one of the major causes of chronic liver disease. It causes a broad spectrum of liver disease ranging from acute self limited hepatitis to fulminant hepatitis, chronic hepatitis including asymptomatic carrier state and chronic active hepatitis. It is also one of the main causes of liver cirrhosis and hepatocellular carcinoma (HCC) (Yalcin et al., 2003).
The proportion of patients suffering from liver disease of unknown cause ranges from 5% in chronic hepatitis up to 40% in fulminant hepatitis cases. These patients may develop severe liver injury leading to an increased risk of cirrhosis. Several studies have called attention to HBV infection in the absence of serological markers or in the presence of anti hepatitis B core (anti-HBc) alone. It has been demonstrated that the serum of some patients without detectable hepatitis B surface Ag (HBsAg) may contain infectious virus. Accumulated data indicated that a low level of HBV DNA remains detectable in serum and liver tissue in some patients who cleared HBsAg from either acute self limited or chronic HBV infection (Honarkar et al., 2004).
The frequency of HBV DNA in patients with cryptogenic chronic liver disease (persistent alteration in liver biochemistry and the etiology could not be determined from clinical, biochemistry or serological data) varies depending on the baseline prevalence of HBV infection in certain geographical area, population studied and techniques used to detect HBV DNA. One study performed on patients with cryptogenic chronic hepatitis found that one of them had detectable HBV DNA indicating an occult HBV infection. During follow up, repeated liver biopsy demonstrated that one fifth had progressed from chronic hepatitis to cirrhosis. These finding indicate that occult HBV infection is a common etiology of cryptogenic chronic hepatitis and a progressive disease at least in some patients (Chan et al., 2002).