Hepatitis D Virus (HDV)

Categorization
Genome: RNA Virus

Transmission

Parenteral Transmission
Sexually Transmitted Disease
Mother-to-Child Transmission

Viral Components

Hepatitis D Virus is solely composed of a nucleocapsid and uses the envelope of Hepatitis B Virus (HBV) to spread from cell to cell. Consequently, HDV can only replicate if a patient is simultaneously infected with HBV.

Sequences of Infection

Co-infection: HBV and HDV may be transmitted simultaneously during a single infective event. Superinfection: HDV may be transmitted to a patient already chronically infected with HBV.

Serology

The immune system elaborates Anti-HDV IgM following infection which in many cases switches to Anti-HDV IgG later on. However, in many cases Anti-HDV IgM does not switch to IgG; therefore, the sole presence of IgM cannot distinguish between acute or chronic infection with HDV.

Clinical Consequences

Co-infection:

Co-infection usually results in acute viral hepatitis similar to that of acute HBV infection alone. However, the presence of HDV does increasee the risk of fulminant hepatitis.

Superinfection:

Superinfection of HDV on a background of chronic HBV infection may appear as a flareup in chronic viral hepatitis or resemble a syndrome akin to acute viral hepatitis. However, in most cases HDV infection also enters a chronic course but increases the risk of developing cirrhosis above that of single infection with HBV.