Viral Infections (Hepatitis, Herpes, etc.)

Viral Infections (Hepatitis, Herpes, etc.)

Viral Infections (Hepatitis, Herpes, etc.)

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Hepatitis Viruses - Liver's Viral Foes

  • General: Viral liver inflammation. Jaundice, fatigue, ↑ALT/AST.
  • HAV (RNA): Fecal-oral ("A for Anus"). Acute only. Vaccine: Yes. IgM anti-HAV (acute).
  • HBV (DNA): Blood/Body fluids ("B for Blood"). Acute; Chronic (5-10% adults, 90% neonates). Vaccine: Yes.
    • Markers: HBsAg (active), Anti-HBs (immune), Anti-HBc IgM (acute), HBeAg (↑infectivity).
    • ⭐ Window period in HBV infection is characterized by positive Anti-HBc IgM and negative HBsAg & Anti-HBs.

  • HCV (RNA): Blood/Body fluids ("C for Circulation"). Acute; Chronic (>70%). Vaccine: No. Dx: Anti-HCV, HCV RNA.
  • HDV (RNA): Needs HBV ("D for Defective/Dependent"). Worsens HBV. Parenteral.
  • HEV (RNA): Fecal-oral ("E for Enteric"). Acute. 📌 Severe in pregnancy ("E for Expectant"). Vaccine: Limited.

Herpesviruses - The Latent Menace

  • Ubiquitous DNA viruses; establish lifelong latency, reactivation common.
  • Transmission: Direct contact, respiratory, vertical.
  • Key Members & Diseases:
    • HSV-1/2: Oral/genital herpes, keratitis, encephalitis.
    • VZV: Chickenpox (varicella), Shingles (zoster).
    • EBV: Infectious mononucleosis, Burkitt's lymphoma, nasopharyngeal Ca. 📌 "MONO Kissing Disease"
    • CMV: Congenital defects; severe disease in immunocompromised.

      ⭐ CMV infection in immunocompromised patients (e.g., transplant recipients) can cause retinitis, colitis, or pneumonitis; histology often shows characteristic 'owl's eye' inclusions.

    • HHV-6/7: Roseola infantum (Exanthem subitum).
    • HHV-8: Kaposi's sarcoma (esp. HIV/AIDS).
  • Diagnosis: PCR (gold standard), serology, Tzanck smear (multinucleated giant cells).
  • Treatment: Acyclovir & prodrugs (valacyclovir). Ganciclovir for CMV. Foscarnet for resistance.

Systemic & Neuro Viruses - Widespread Impact

  • Dengue (Arbovirus)

    • Vector: Aedes aegypti.
    • Spectrum: DF, DHF, DSS.
    • DF: "Breakbone fever"; high fever, retro-orbital pain, rash, myalgia.
    • DHF/DSS warning: Abd pain, vomiting, mucosal bleed, ↓platelets, ↑HCT.
  • Influenza (Orthomyxovirus)

    • Types A & B (epidemics); droplet spread.
    • Sx: Abrupt fever, cough, sore throat, myalgia.
    • Complications: Pneumonia.
    • Antivirals (Oseltamivir) if <48 hrs.
  • Rabies (Rhabdovirus)

    • Zoonotic; animal bite (saliva).
    • CNS: Retrograde axonal transport; Negri bodies (pathognomonic).
    • Phases: Prodromal → Furious (hydrophobia) / Paralytic → Death.
    • PEP: Wound care, vaccine, RIG.

⭐ Rabies has the highest case-fatality rate of any infectious disease; post-exposure prophylaxis is crucial and highly effective if administered promptly.

Negri bodies in neurons from rabies-infected brain

High-Yield Points - ⚡ Biggest Takeaways

  • Hepatitis B serology is key: HBsAg (active infection), Anti-HBs (immunity/recovery), IgM Anti-HBc (acute).
  • Hepatitis C: Often asymptomatic, high risk of chronic liver disease & HCC; DAAs offer cure.
  • Herpes Simplex (HSV): Painful grouped vesicles; Tzanck smear shows multinucleated giant cells; Acyclovir is mainstay.
  • Varicella-Zoster (VZV): Shingles is unilateral, painful dermatomal vesicular eruption; risk of post-herpetic neuralgia.
  • Dengue fever: High fever, retro-orbital pain, thrombocytopenia, rash; monitor for warning signs like bleeding.

Practice Questions: Viral Infections (Hepatitis, Herpes, etc.)

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A 2 month old baby presented with acute icteric viral hepatitis. The mother is a known hepatitis B carrier. Mother's hepatitis B virus serological profile is MOST likely to be:

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Flashcards: Viral Infections (Hepatitis, Herpes, etc.)

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Most common cause of chronic hepatitis (prevalence) is hepatitis _____

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Most common cause of chronic hepatitis (prevalence) is hepatitis _____

B

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