Hepatitis D Virus: An Important Viral Agent in Hepatitis B Virus Endemic Regions a Review

More than 370 million individuals worldwide are Hepatitis B virus (HB V) carriers and about 5% of these individuals are co-infected with Hepatitis D virus (HDV). Hepatitis D virus is a defective virus that requires the obligatory help of Hepatitis B virus for its replication and expression. Hepatitis D virus is known to induce acute or chronic liver diseases. Individuals having HBV-HDV co-infection are prone to present with more severe acute disease and higher risk of fulminant hepatitis, cirrhosis and hepatocellular carcinoma (HCC) than those having Hepatitis B virus infection alone. Based on phylogenetic analysis, Hepatitis D virus is classified into 8 genotypes. Except genotype 1 which is found worldwide, genotypes 2-8 have specific geographical distribution. The transmission of Hepatitis D virus is similar to that of Hepatitis B virus (i.e. by blood and blood products, perinatal and also sexual intercourse). Hepatitis D virus can be diagnosed by serological analysis, molecular techniques and histo-immunochemistry. Several antiviral agents are under trial with varying degrees of efficacy. However, vaccination against Hepatitis B virus has helped in the control of Hepatitis D virus.