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Hepatitis B

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Hepatitis B virus is a DNA virus. It can cause both acute viral hepatitis and chronic hepatitis. It's usually prevented by a childhood vaccine. Treatment exists for chronic hepatitis B.

Etiology

HBV is very infective, 50 – 100 times more infective than HIV. Like hepatitis C and D, transmission usually occurs due to:

  • Parenteral
  • Sexual (esp. men who have sex with men)
  • Perinatal

Clinical features

Hepatitis B can cause both acute and chronic hepatitis.

For acute hepatitis, about 30% of persons are asymptomatic. Symptomatic persons generally have jaundice and nonspecific symptoms like fatigue and anorexia.

Chronic hepatitis occurs more frequently in children than adults. It’s usually asymptomatic, but problematic because it can cause chronic liver disease and hepatocellular carcinoma.

Microbiology

The virus consists of the so-called Dane particle and the coat and free particles. The Dane particle contains the virus core, the core antigen (HBcAg), and the e antigen (HBeAg). The coat and free particles contain the surface antigen (HBsAg).

Diagnosis and evaluation

Diagnosis is based on serology, including anti-HBs, anti-HBc, and anti-HBe, and detection of the two HBV antigens, HBeAg and HBsAg.

  • HBsAg – general marker of HBV infection
  • HBeAg – marker for infectiveness (indicates replicating virus)
  • HBV-DNA – marker for infectiveness (indicates replicating virus)
  • Anti-HBs – general marker of immunity
  • Anti-HBc IgM – marker of acute infection
  • Anti-HBc IgG – marker for past or chronic infection

In acute infection, HBsAg, HBeAg, and IgM anti-HBc are present. Seroconversion from HBsAg to anti-HBs indicates resolved infection.

In chronic infection, HBsAg and IgG anti-HBc are present.

In a vaccinated person, anti-HBs alone is present.

Treatment

Acute hepatitis B requires no treatment.

Chronic hepatitis B is treated with pegylated interferon or nucleoside analogues like entecavir or tenofovir.

Prevention

HBV can be prevented by vaccine. The vaccine is part of the childhood vaccination programme and is given right after birth (in Hungary) or at 3 months (in Norway). For those who were not vaccinated in childhood, the vaccine is recommended for those at high risk, like health care workers, and teenagers.

Passive immunization (HBIG) is used as post-exposure prophylaxis and must be given within 48 hours.