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Viral Hepatitis & Liver Anatomy

Jun 7, 2025

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Overview

This lecture covers the five main types of viral hepatitis (A, B, C, D, E), focusing on their virology, transmission, clinical features, diagnosis, and liver pathology, highlighting key differences for exam preparation.

Normal Liver Anatomy & Histology

  • Liver is the largest human organ, divided into right and left lobes; right lobe is four times larger than left.
  • Liver receives dual blood supply: hepatic artery (oxygenated blood) and portal vein (deoxygenated blood).
  • Blood exits via the hepatic (central) vein; bile produced by hepatocytes drains through the bile duct.
  • Liver lobules are hexagonal structures centered on a central vein with portal triads (branches of hepatic artery, portal vein, and bile duct) at the corners.
  • Hepatocytes form cords connecting the central vein and portal triads, with sinusoids (capillaries) lined by endothelial and Kupffer cells.
  • Space of Disse lies between hepatocytes and sinusoids, contains Ito cells (fat/vitamin A storage, can cause fibrosis when activated).

Overview of Viral Hepatitis Types (A-E)

  • Hepatitis A, C, D, E are RNA viruses; Hepatitis B is a DNA virus.
  • Virus families: A—Picornaviridae, B—Hepadnaviridae, C—Flaviviridae, D—Deltaviridae, E—Hepeviridae.
  • A & E are non-enveloped; B, C, D are enveloped.
  • A & E transmitted by fecal-oral route; B, C, D by parenteral (blood/needles), sexual, and vertical (mother-to-child) routes.
  • Incubation periods: A (30 days), E (40 days), C (50 days), B & D (60-90 days).

Clinical Features & Course

  • Acute hepatitis can be caused by all types; fulminant (severe) form seen in all, especially E in pregnancy.
  • Chronic hepatitis occurs only with B, C, D—not A or E.
  • Chronic hepatitis can lead to carrier state, cirrhosis, and hepatocellular carcinoma (HCC); A and E do not cause chronicity or sequelae.
  • Hepatitis A: common cause of acute hepatitis in children; E: common in adults and pregnancy-related fulminant hepatitis.
  • B: more prevalent globally; C has higher rate of chronicity.

Diagnosis & Serology

  • Hep A: diagnosed by virus/antigens in blood/stool, anti-HAV IgM (acute), and IgG (past infection).
  • Hep B: serological markers include two antigens (HBsAg, HBeAg) and four antibodies (anti-HBs, anti-HBe, anti-HBc IgM & IgG).
    • HBsAg = current infection, anti-HBs = recovery/vaccination.
    • HBeAg = high infectivity, anti-HBe = low infectivity.
    • IgM anti-HBc = acute; IgG anti-HBc = chronic.
  • Hep C: diagnosed by viral antigens and anti-HCV antibodies (1st to 3rd generation).
  • Hep D: requires Hep B (defective virus); diagnosis depends on presence of anti-HDV and Hep B markers.
    • Co-infection: B and D enter together (mostly acute, good prognosis).
    • Superinfection: D infects a B carrier (mostly chronic, poor prognosis).
  • Hep E: diagnosed by anti-HEV IgM (acute) and IgG (past).

Pathological Spectrum: Acute & Chronic Hepatitis

  • Acute hepatitis (all types): balloon degeneration, Councilman bodies, dropout necrosis, bridging necrosis, portal tract lymphocytes.
  • Chronic hepatitis (B, C, D): piecemeal necrosis (limiting plate loss), interface hepatitis (lymphocytes at limiting plate), bile duct proliferation, triaditis, Councilman bodies, Kupffer cell hyperplasia, bridging necrosis and bridging fibrosis (centro-central, porto-portal, centro-portal).

Key Terms & Definitions

  • Portal Triad — Group of hepatic artery, portal vein, and bile duct at liver lobule corner.
  • Kupffer Cell — Specialized macrophage in liver sinusoids.
  • Space of Disse — Space between hepatocytes and sinusoids, contains Ito cells.
  • Balloon Degeneration — Swollen hepatocytes seen in acute hepatitis.
  • Councilman Body — Apoptotic hepatocyte with eosinophilic cytoplasm, no nucleus.
  • Bridging Necrosis/Fibrosis — Necrosis or fibrosis that connects portal-to-portal, portal-to-central, or central-to-central areas.
  • Piecemeal Necrosis — Destruction of hepatocytes at the limiting plate (seen in chronic hepatitis).

Action Items / Next Steps

  • Review and draw diagrams and flowcharts for hepatitis types and liver histology.
  • Memorize serological markers, their sequence, and clinical interpretation for Hepatitis B.
  • Complete all related long/short answer and MCQ questions in the notes and app question bank.

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