Notes on Viral Hepatitis

Overview of Hepatitis Types

• Discussion of 5 types: Hepatitis A, B, C, D, E
• Common question formats in university exams:
  • Long questions: Often on Hepatitis B
  • Short questions: All types of viral hepatitis are important

Anatomy of the Liver

Normal Liver Anatomy

• Largest organ in the human body
• Composed of right and left lobes:
  • Right lobe: 4x larger than left lobe

Dual Blood Supply of the Liver

• Unique feature of the liver: Dual blood supply
  • Hepatic artery: Supplies oxygenated blood from aorta
  • Portal vein: Carries deoxygenated blood from GI tract
• Single exit through the hepatic vein (Central vein)

Classical Lobule Model of the Liver

• Structure divided into hexagonal lobules
• Central vein at the center surrounded by portal triads (hepatic artery, portal vein, bile duct)
• Hepatocytes connect between the central vein and portal triads
• Sinusoids: Blood capillaries lined by endothelial cells and Kupffer cells

Key Points about Viral Hepatitis

Types of Hepatitis Viruses

| Type | Virus Name | Family | RNA/DNA | Envelope | Transmission Root | |-------|----------------------|--------------------------|---------|---------------|--------------------------| | A | Hepatitis A virus | Picornaviridae | RNA | No | Fecal-oral | | B | Hepatitis B virus | Hepadnaviridae | DNA | Yes | Parenteral, sexual, vertical | | C | Hepatitis C virus | Flaviviridae | RNA | Yes | Parenteral, sexual, vertical | | D | Hepatitis D virus | Delta virus | RNA | Yes | Parenteral, sexual, vertical | | E | Hepatitis E virus | Hepeviridae | RNA | No | Fecal-oral |

Transmission Routes

• Hepatitis A and E: Transmitted via fecal-oral route (contaminated food/water)
• Hepatitis B, C, D: Transmitted mainly via:
  • Parenteral route: Blood products, shared syringes
  • Sexual route: Less common
  • Vertical route: From mother to fetus via placenta

Incubation Periods

• Hepatitis A: Approximately 30 days
• Hepatitis E: Approximately 40 days
• Hepatitis C: Approximately 50 days
• Hepatitis B and D: Approximately 60-90 days

Clinical Features

• Acute hepatitis: All five types can cause
• Fulminant hepatitis: Rare, but can occur in all types
• Chronic hepatitis: Only B, C, and D can cause; A and E do not lead to chronic infection
• Chronic hepatitis can lead to:
  • Carrier state
  • Hepatocellular carcinoma (HCC)
  • Cirrhosis

Laboratory Diagnosis

• For each hepatitis type, focus on:
  • Positive agent
  • Morphology of the virus
  • Mode of transmission
  • Clinical features
  • Lab diagnosis
• Hepatitis A:
  • Antibodies: IgM (recent infection), IgG (past infection)
  • Virus detected in blood and stool
• Hepatitis B:
  • Antigen-antibody markers (e.g., HBsAg, HBeAg)
  • Sequence of markers indicates infection status
• Hepatitis C, D, E:
  • Similar approach with focus on respective virus characteristics

Histopathological Features

• Acute hepatitis microscopy: Similar across all five types
  • Balloon degeneration, Councilman bodies, necrosis, and inflammatory infiltrate
• Chronic hepatitis microscopy: Features differ from acute
  • Piecemeal necrosis, portal triad inflammation, and bridging fibrosis

Prognosis

• Generally excellent for Hepatitis A and E
• Hepatitis B and C: Vary based on acute or chronic stages

Conclusion

• Understanding anatomy, transmission, clinical features, lab diagnostics, and pathologic aspects are crucial for mastering the topic of viral hepatitis.