Hepatitis E and Hepatitis D

Hepatitis E

• Family: Hepeviridae
• Genus: Hepevirus

Virion morphology and size:

• Nonenveloped, icosahedral nucleocapsid symmetry, spherical particles, 30-34 nm diameter
• Like HAV

Nucleic acid:

• Linear, positive-sense, single-stranded RNA, ~7.2 kb in length 

Common Human Exposure Routes:

• Most epidemics water-borne, some food-borne from a fecally contaminated cause
• Person-to-person spread relatively uncommon
• Blood transmission is rare but has been reported.

Incubation Period:

• Usually 3-8 weeks, but longer and shorter periods have been reported.

Clinical Manifestations

• Associated with cholestasis.
• Most important cause of fulminant hepatitis in pregnancy.
• In India, it is the most common form of acute hepatitis of adults
• Overall most common is Hepatitis A
• High case fatality rate (20-40%) in pregnant women, especially in the last trimester of pregnancy.

Laboratory Test(s)(none FDA approved)

• IgG and IgM antibody assays have been developed but vary widely in sensitivity and specificity.
• Virus detected by RT-PCR

Hepatitis D (HDV) or Delta virus

• Genus: Genus Deltavirus

Important Point:

• It is defective RNA virus dependent on the helper function of HBV for its replication and expression.

Morphology

• It contains single-stranded RNA (ssRNA) – Defective RNA.
• It has no independent existence and can survive and replicate only as long as HBV infection persists in the host.
• It resembles some plant viruses, such as viroids or satellite viruses.
• Delta core of HDV is encapsidated by an outer envelope of HBs Ag, so it requires the cooperative function of HBV.
• Intracellular replication of HDV RNA can occur without HBV but liver injury requires the presence of HBV.

Clinical Manifestations:

• HDV can cause two types of infection.
• HDV superinfection of a person with chronic Hepatitis B (HBV) has the worst prognosis with high likelihood of fulminant hepatitis and death.

Treatment:

• IFN-alpha