HEPATITIS

Hepatitis A Virus is a picornavirus.
Hepatitis B Virus is a hepadnavirus.
Hepatitis C Virus is a flavivirus. It is a single-stranded RNA virus.


Hepatitis B
A positive anti-HBc (IgM) and HBsAg suggests acute infection.

When the infection resolves, HBsAg becomes negative and anti-HBc (IgG) is positive.

In patients who have been vaccinated, HBsAg is negative and anti-HBs is positive.

HbcAg is the first detectable antigen in acute infection but is also detectable in chronic infection.

HbsAg is detectable in chronic infection.

HbsAb is a sign of previous infection or immunisation.

HBeAg (not HBcAg) is the best marker of infectivity, and is used as an important criteria for selection of patients who have chronic hepatitis B for interferon (α-2B)
therapy.
HBV DNA and HBeAg levels are measured in response to the therapy and undetectable levels would be considered successful treatment.

10% of patients with hepatitis B develop chronic infection (as compared to hepatitis C where 80% develop chronic infection).

30% of patients with hepatitis C develop hepatocellular carcinoma over 30 years. 20% develop cirrhosis over 20 years.

The treatment options are ribavirin or PEG (polyethylene glycolated) interferon.

IFN α is only effective in clearing the virus in 25% of patients.

Meta-analysis of data strongly suggests a two to three-fold enhanced efficacy of interferon-ribavirin combination therapy over interferon monotherapy in all major subgroups of chronic hepatitis C patients.

In hepatitis C, response to therapy is determined by normalisation of hepatic transaminases and undetectability of hepatitis C RNA in plasma.

Hepatitis D (delta) is a superimposed infection to Hepatitis B.

Hepatitis E causes acute illnesses, and does not result in a chronic carrier state. It is usually transmitted in a faeco oral route (similar to hepatitis A). It occurs mostly in developing countries and is widespread in India, Asia, Africa and Central America.

Hepatitis G virus or GBV-C does not appear to cause progressive liver disease.

Autoimmune hepatitis occurs in younger to middle aged women. 25% present as acute hepatitis, but the onset is usually insidious. Amenorrhoea is relatively common. It is associated with hyperglobulinaemia rather than hypoglobulinaemia. 60% are associated HLAB8, DR3 and DW3. The sicca syndrome (xerostomia/dry eyes,keratoconjunctivitis sicca may occur).

Category: Gastroenterology Notes