Epidemiology and Aetiology

  • Major health problem – 300 million carriers
  • Incubation 1 – 4 mths
  • Parenteral transmission – sexual, IV, perinatal
  • 0.5% of UK population are carriers, but this is as much as 10-15% in some countries in the developing world. in some far eastern countries, 1/3 of people are carriers. E.g. in Yemen ¼ of the population have hep B

Presentation

Acute Hepatitis B

  • Incubation period 6 weeks – 6 months
  • 1% of patients will develop liver failure
  • 90% will recover
  • 10% will go on to develop chronic hepatitis B infection
  • Jaundice, malaise, abdominal pain, nausea & fever – 1 to 3 months
  • 70% anicteric (not jaundiced)

Maternal transmission is different

  • 90% of newborns born to infected mothers will have chronic hepatitis B infection
  • Up to 25% will have chronic complications. Including:
    • Cirrhosis
    • Hepatocellular carcinoma

Diagnosis

  • Derranged LFTs
  • Positive HBsAg
  • Carrier status is indicated by presence of e antigen. ‘e-antigen positive carrier’

Understanding Hepatitis B testing

There are several antigens and antibodies that are present during, and following Hepatitis B infection. Understanding which of these is present and when can help you identify if a persen has a current or past infection, and their immunity status.

Clinical Status Serological Markers
Immunity following previous natural exposure Anti-HBc (may be negative if infection was a long time ago)
Anti-HBs
Previously Vaccinated Anti-HBs
Acute Infection HBs-Antigen
Anti-HBc
HBV-DNA
HBe-Antigen (may be negative depending on timing)
Chronic Infection HBs-Antigen
Anti-HBc
HBV-DNA
(all above still positive 6 months after diagnosis)

 

Pathology

In chronic disease, viral DNA may become incorporated into host DNA. HbsAg is present on the surface of infected hepatocytes, and this causes T cells to induce apoptosis in these cells. The pathogenesis is different to that of HAV (Hepatitis A Virus) , where the apoptosis is not induced by the immune system, but by the infected cell itself – thus HAV does not have the ability to cause chronic disease.

Complications

  • Acute liver failure rare – 0.1 to 0.5%
  • Chronic Hepatitis B is specified as viraemia at 6 months after initial diagnosis/sympotms
  • Chronic infection depends on age of infection:
    • 90% of people who get the disease in vertical transmission (i.e. from their mum) will develop chronic disease
    • 5-10% of adults will develop chronic disease
  • 30% of people with chronic infection will get cirrhosis
  • In chronic HBV 40% men and 15% women die from liver failure

Management

  • Antiviral therapy for selected patients with chronic infection
    • Lamivudine
    • Entecavir
    • Tenofovir (adefovir)
  • The aim of treatment is to reduce the risk of complications. Therefore patients who already have cirrhosis are likely not to benefit. Other factors when deciding who to treat include:
    • HBe-antigen status
    • Elevated Transaminase
    • HBV DNA levels
    • Not cirrhotic
  • Prevented by vaccination

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