Acute Hepatitis B Virus Infection

 

Incubation Period :

  • – Few weeks to 6 months
  • – Average incubation period : 60-90 days

Prodromal Features :

  • – Malaise
  • – Nausea
  • – Vomiting
  • – Serum-sickness-like illness : fever, arthralgia, arthritis, rash

Pathogenesis of Prodromes :

  • – HBsAg-anti HBs Ab complexes that activate complements that are deposited in the synovium and walls of cutaneous blood vessels
  • – Jaundice develops only in 30% cases
  • – Clinical symptoms and jaundice usually disappear within 1-3 months
  • – In 80% cases HBsAg disappears by 12 weeks after the onset of illness

Lab findings of acute HBV

  • – Typical : ALT : 1000-2000 U/L
  • – Peak ALT does not correlate with prognosis
  • – INR is the best predictor of prognosis
  • ‘Late onset liver failure’ occur more in patients older than 40 years

Clinical outcome of HBV infection 

Acute HBV :

  • – Perinatal exposure causes chronic HBV carrier state in 95% of persons
  • – Children exposed during 1st 5 years of life have a 30% chance developing chronic HBV
  • – Only 2-5% of adults with intact immune system become chronically infected
  • – 2/3rd patients have asymptomatic or subclinical illness that goes unrecognised

Chronic HBV :

  • – Progressive liver disease (cirrhosis + HCC) develop in one quarter to one third of patients who acquire the infection in the first few years of life
  • – HCC is 4 times more common in male in comparison to female
  • – Clearance of HBsAg from serum in HBV related cirrhosis is associated with improved liver histology and function and improved long term survival
  • – HBsAg clearance is not an absolute safeguard against future HCC development

 


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