Hepatitis Viruses

Hepatitis Viruses Overview - Liver's Viral Foes

• Five main hepatotropic viruses: Hepatitis A (HAV), B (HBV), C (HCV), D (HDV), and E (HEV), primarily targeting liver cells.
• Key Transmission Routes:
  • Fecal-Oral (Enteric): HAV, HEV (📌 "Vowels go through bowels")
  • Parenteral, Sexual, Vertical: HBV, HCV, HDV (Blood-borne, body fluids)
• Genomic Classification:
  • RNA Viruses: HAV, HCV, HDV, HEV
  • DNA Virus: HBV (Family: Hepadnaviridae)

⭐ All hepatitis viruses are RNA viruses except Hepatitis B virus (HBV), which is a DNA virus (Hepadnaviridae family).

HAV & HEV - Enteric Attackers

• Transmission: Fecal-oral. 📌 "Vowels (A,E) from Bowels".
• Virus: RNA, non-enveloped.
  • HAV: Picornavirus.
  • HEV: Hepevirus.
• Illness: Acute hepatitis; usually self-limiting. No chronic state (except HEV in immunocompromised).
• Diagnosis: IgM anti-HAV/HEV (acute); IgG (past/immunity). HEV RNA.
• Key Points:
  • HAV: Outbreaks (food/water); children often asymptomatic.

  ⭐ Hepatitis E virus (HEV) infection during pregnancy, particularly in the third trimester, is associated with a high risk of fulminant hepatic failure and mortality (around 20-30%).

• Prevention: Hygiene. HAV vaccine.

oka

HBV - B-ware the Beast

• Partially dsDNA virus (Hepadnaviridae); Dane particle is infectious virion.
• Transmission: Parenteral, sexual, perinatal (📌 Blood, Birthing, Bonking).
• Incubation: 45-180 days. High risk of chronicity (adults 5-10%, neonates ~90%), leading to cirrhosis, HCC.
• Pathology: "Ground-glass" hepatocytes (HBsAg accumulation).
• HBeAg: high infectivity; Anti-HBe: lower replication.
• Extrahepatic: Polyarteritis nodosa, glomerulonephritis.
• Vaccination: Recombinant HBsAg. Treatment: Antivirals (e.g., Tenofovir).

⭐ HBsAg indicates active HBV infection (acute or chronic). Anti-HBs indicates immunity (either from vaccination or resolved infection). Anti-HBc IgM is a marker of acute infection.

HCV & HDV - C-quel & D-pendent Duo

• HCV (Hepatitis C Virus):
  • RNA virus (Flaviviridae); parenteral transmission (IVDU).
  • High chronicity (~80%) → Cirrhosis, HCC. 📌 C: Chronic, Cirrhosis, Carcinoma.
  • Dx: Anti-HCV, HCV RNA. Rx: DAAs. No vaccine.
• HDV (Hepatitis D Virus):
  • Defective RNA virus; requires HBsAg (HBV). 📌 D: Defective, Dependent.
  • Transmission: Parenteral.
  • Superinfection (on chronic HBV) worse than coinfection.
  • Prevention: HBV vaccine.

⭐ Hepatitis D virus (HDV) is a defective RNA virus that requires HBsAg (from HBV) for its replication and transmission; HDV superinfection in a chronic HBV carrier has a more severe prognosis than HBV/HDV co-infection.

Hepatitis Dx & Prevention - Test, Treat, Thwart

• Diagnosis (Dx):
  • Serology: Detects antibodies (IgM/IgG) & antigens (HBsAg, HBeAg, Anti-HCV). Core for staging.
  • NAT/PCR: Quantifies viral load (HBV DNA, HCV RNA); guides treatment.
• Prevention (Thwart):
  • Vaccination: HAV, HBV (universal & high-risk groups).
  • Screening: Blood donors, pregnant women (HBV, HCV), high-risk individuals.
  • Hygiene: Handwashing, safe water (HAV, HEV).
  • Safe Practices: Safe sex, no needle sharing.

⭐ Effective vaccines are available for Hepatitis A Virus (HAV) and Hepatitis B Virus (HBV), forming a cornerstone of prevention strategies.

High‑Yield Points - ⚡ Biggest Takeaways

• HAV: RNA virus, fecal-oral route, acute infection only, IgM anti-HAV diagnoses.
• HBV: DNA virus, parenteral/sexual/vertical, causes cirrhosis/HCC, HBsAg marker, ground-glass hepatocytes.
• HCV: RNA virus, parenteral (IVDU), high chronicity & HCC risk, HCV RNA for diagnosis.
• HDV: Defective RNA virus, needs HBV (co/superinfection), superinfection more severe.
• HEV: RNA virus, fecal-oral route, high mortality in pregnant women.
• Vaccines: Available for HAV & HBV; none for HCV.
• HBV serology: (HBsAg, anti-HBs, anti-HBc) crucial for infection status.