Viral Hepatitis

Hepatitis Viruses A & E - Acute Enteric Attackers

• General Features:

  • Transmission: Fecal-oral route. 📌 "Vowels from the Bowels" (A & E).
  • Illness: Acute hepatitis; generally no chronic state (exception: HEV in immunosuppressed).
  • Virus Type: RNA viruses.

• Hepatitis A Virus (HAV):

  • Family: Picornaviridae.
  • Incubation: 2-6 weeks (average 4 weeks).
  • Clinical: Jaundice, fever, nausea. Often asymptomatic/mild in children.
  • Diagnosis: ↑ Anti-HAV IgM (acute infection); Anti-HAV IgG (past infection/immunity).
  • Complications: Fulminant hepatitis rare (<0.5%).
  • Prevention: Vaccination, hygiene.

• Hepatitis E Virus (HEV):

  • Family: Hepeviridae.
  • Incubation: 2-10 weeks (average 5-6 weeks).
  • Clinical: Similar to HAV; self-limiting acute hepatitis.
  • Diagnosis: ↑ Anti-HEV IgM (acute infection); Anti-HEV IgG (past infection/immunity); HEV RNA.
  • Special Populations:

    ⭐ High mortality (15-25%) in pregnant women (especially 3rd trimester, with Genotypes 1 & 2).

  • Chronic HEV: Can occur in immunosuppressed individuals (Genotype 3).
  • Reservoir: Zoonotic (pigs for Genotypes 3 & 4).

Hepatitis B Virus - Decoding Serology's Maze

• DNA virus (Hepadnaviridae); Dane particle = complete infectious virion.
• Key Serological Markers & Interpretation:
  • HBsAg: Surface Antigen. Active infection (acute/chronic). Chronic if >6 months. (📌 Surface = Sick)
  • Anti-HBs: Surface Antibody. Immunity (resolved infection/vaccination). Protective if >10 mIU/mL. (📌 Anti-S = Safe)
  • Anti-HBc: Core Antibody.
    • IgM Anti-HBc: Acute infection/flare. Key for "window period". (📌 IgM = Miserable/Recent)
    • IgG Anti-HBc: Past/ongoing chronic infection. Lifelong. (📌 IgG = Gone/Long-term)
  • HBeAg: e Antigen. Active viral replication, high infectivity. (📌 e Ag = extra contagious)
  • Anti-HBe: e Antibody. Seroconversion, ↓ replication, ↓ infectivity.
  • HBV DNA: Viral load; monitors treatment.

⭐ Window Period: HBsAg cleared, Anti-HBs not yet up. IgM Anti-HBc is the sole positive marker.

Hepatitis C & D Viruses - Chronic Threats, Deadly Duet

Hepatitis C Virus (HCV)

• RNA virus (Flaviviridae); primarily parenteral transmission (IVDU, blood).
• High chronicity rate: ~80% progress to chronic infection.
• Leads to: Chronic hepatitis → Cirrhosis → Hepatocellular Carcinoma (HCC).
• Extrahepatic: Cryoglobulinemia, MPGN, Porphyria Cutanea Tarda (PCT), Lichen Planus.
  • 📌 Mnemonic: Creates Many Problems Later (Cryo, MPGN, PCT, Lichen Planus).
• Diagnosis: Anti-HCV Ab (screen), HCV RNA (active infection/viral load).
• Treatment: Direct-Acting Antivirals (DAAs) - high cure rates. No vaccine.

Hepatitis D Virus (HDV) - "Delta Agent"

• Defective RNA virus; requires Hepatitis B surface antigen (HBsAg) for replication & transmission.
• Transmission: Parenteral, similar to HBV.
• Two scenarios:
  • Co-infection (HBV+HDV simultaneously): Acute, severe hepatitis; often self-limiting. Lower chronic HDV risk.
  • Superinfection (HDV in chronic HBV carrier): Severe exacerbation; rapid progression to cirrhosis in ~70-80%.
• Diagnosis: Anti-HDV Ab, HDV RNA. Must have HBsAg.
• Treatment: Peg-IFNα (at least 48 weeks); Bulevirtide.
• Prevention: HBV vaccination (prevents HDV).

⭐ HDV superinfection in a chronic HBV carrier significantly accelerates progression to cirrhosis.

High‑Yield Points - ⚡ Biggest Takeaways

• HAV & HEV: Fecal-oral route; HAV is acute only; HEV severe in pregnancy.
• HBV: Parenteral/sexual/vertical transmission; HBsAg (infection), Anti-HBs (immunity); risk of HCC.
• HCV: Mainly parenteral; high chronicity (~80%); leads to cirrhosis, HCC.
• HDV: Defective virus requiring HBV; superinfection is more severe.
• Key Serology: IgM anti-HAV (acute A); HBsAg (HBV infection); HCV RNA (active C).
• Biopsy: Councilman bodies, ballooning degeneration, lymphocytes; ground-glass cells (HBV), lymphoid follicles (HCV).