Section VI. HEPATITIS D VIRUS (HEPATITIS B VIRUS, HEPATITIS D VIRUS )
7-23. VIRUS STRUCTURE
Little is known as to the true structure and classification of the hepatitis D virus (delta).
It is thought to be a single-stranded RNA virus and is considered to be a defective agent
since it requires the presence of HBsAg in order to replicate.
7-24. MODE OF TRANSMISSION
The HDV is transmissible via the parenteral route. Persons with frequent and
repeated blood exposures (drug addicts, hemophiliacs, multiple blood transfusions, and so forth)
appear to be at higher risk for contacting this virus. Since HDV requires the presence of
HBV, contact with body fluids contaminated with HBV may also result in the
transmission of HDV. A delta infection should be suspected in patients with fulminant
hepatitis and in chronic HBV carriers who have a sudden deterioration in clinical course.
7-25. INCUBATION PERIOD AND INFECTIVITY
Since the hepatitis D virus is strictly dependent upon HBV, its incubation period is
considered the same as HBV (45 days, range 30-120 days). The patient with a delta
infection is considered infectious as long as the HBsAg is detectable.
7-26. HEPATITIS D VIRUS IMMUNOLOGICAL ASSAYS
a. Anti-HDV IgM indicates acute infection.
b. Anti-HDV indicates recent HDV infection or progression to chronic infection.
7-27. TYPES OF HEPATITIS D VIRUS INFECTIONS
The clinical course of HDV infection depends upon the type of infection:
coinfection with HBV or superinfection in a patient who is already infected with HBV.
a. Coinfection. This type of infection is a simultaneous acute HDV infection in
conjunction with an acute HBV infection. Since the majority of the cases of acute HBV
are short lived, the severity of the HDV infection is limited. However, the liver damage
can become extensive and, when combined with the damage caused by the hepatitis B
virus, can induce a more severe case of hepatitis.
b. Superinfection. A superinfection of HDV in a hepatitis B chronic carrier
produces the most severe damage. It may produce new hepatitis symptoms or may
aggravate existing conditions. This type of infection is often severe and may cause
fulminant hepatitis. Many superinfected carriers go on to develop chronic delta