Viral Infections in Immunocompromised Hosts

Viral Infections in Immunocompromised Hosts

Viral Infections in Immunocompromised Hosts

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Intro: IC Viral Infections - The Ground Rules

  • Core issue: Impaired Cell-Mediated Immunity (CMI) is the primary defect.
  • Impact: Leads to ↑ susceptibility, ↑ severity, prolonged duration, and atypical clinical presentations.
  • Common pattern: Reactivation of latent viruses (e.g., HSV, VZV, CMV) is frequent.
  • New infections: Can also be unusually severe and disseminated.
  • Diagnostic challenge: Atypical lesions often necessitate skin biopsy for confirmation.
  • Management principles: Higher antiviral doses, longer treatment courses; be alert for drug resistance. Prophylaxis is key in select groups.

⭐ Viral infections in IC hosts often manifest with unusually large, numerous, persistent, ulcerative, or even necrotic skin lesions.

Herpesviruses (HSV & VZV) - Fiery Foes

  • Opportunistic infections in IC hosts; atypical presentations common.
  • HSV (Herpes Simplex Virus):
    • Chronic, ulcerative, hypertrophic, or verrucous lesions common.
    • Dissemination risk: hepatitis, pneumonitis, encephalitis.
    • Dx: PCR (gold standard), Tzanck smear (multinucleated giant cells).
    • Tx: Acyclovir (high-dose). Resistance: Foscarnet, Cidofovir.
  • VZV (Varicella-Zoster Virus):
    • Zoster: ↑ severity, duration, pain; ↑ risk of dissemination (cutaneous/visceral).
    • Chronic VZV: persistent, hyperkeratotic lesions.
    • ↑ risk/severity of Post-Herpetic Neuralgia (PHN).
    • Tx: Valacyclovir, Famciclovir. IV Acyclovir for severe/disseminated cases.

⭐ Hutchinson's sign (vesicles on tip/side/root of nose) in Herpes Zoster Ophthalmicus indicates nasociliary (V1) involvement, high risk of ocular complications. Hutchinson's sign in Herpes Zoster Ophthalmicus

Poxviruses & HPV - Persistent Pests

  • Molluscum Contagiosum (MC) in Immunocompromised:
    • Manifestations: Numerous, large (>1 cm, giant), atypical (e.g., crusted, verrucous), persistent lesions.
    • Common sites: Face, neck, intertriginous, anogenital.
    • Indicator: Often reflects severe immunosuppression (e.g., HIV with CD4 < 100 cells/µL).
    • Management: HAART in HIV is primary. Destructive (cryo, curettage), topical (cidofovir, imiquimod).
    • Giant molluscum contagiosum on face
  • Human Papillomavirus (HPV) in Immunocompromised:
    • Manifestations: Extensive, recalcitrant warts (common, plantar, flat, anogenital).
    • Increased risk: Dysplasia and squamous cell carcinoma (SCC), especially with high-risk types (16, 18, 31, 33).
    • Management: Difficult due to high recurrence. Destructive methods, topical (imiquimod, 5-FU), intralesional cidofovir. Regular screening for malignancy.

⭐ In transplant recipients, HPV-associated SCCs are more frequent, aggressive, and often multiple.

CMV & HHV-8 (Kaposi's) - Deeper Threats

  • Cytomegalovirus (CMV):
    • Reactivates in immunosuppression (AIDS CD4 < 50/µL, transplant).
    • Sites: Retina ("pizza-pie" fundoscopy), GI (colitis, esophagitis), pneumonitis.
    • Dx: PCR, biopsy ("owl's eye" inclusions).
    • Rx: Ganciclovir, Valganciclovir, Foscarnet.
  • Human Herpesvirus-8 (HHV-8) / Kaposi's Sarcoma (KS):
    • HHV-8 driven angioproliferative malignancy, common in AIDS.
    • Clinical: Violaceous/brownish patches, plaques, nodules (skin, oral mucosa). May involve GI, lungs.
    • Dx: Biopsy (spindle cells, neovascularization).
    • Rx: HAART (AIDS-KS); local (cryo, intralesional chemo); systemic chemo for advanced disease. Kaposi Sarcoma Lesions

⭐ Kaposi's Sarcoma is the most common malignancy in untreated AIDS patients; HAART often induces regression.

High‑Yield Points - ⚡ Biggest Takeaways

  • Herpesviruses (HSV, VZV, CMV) cause severe, disseminated, or chronic infections.
  • Atypical clinical presentations are frequent, often delaying diagnosis.
  • CMV commonly affects retina, GIT, and lungs, especially in AIDS/transplant patients.
  • Molluscum contagiosum can be giant, numerous, or widespread, particularly in HIV.
  • HPV infections: extensive warts and ↑ risk of malignancy.
  • Early diagnosis, aggressive antiviral therapy, and prophylaxis are critical.
  • Watch for antiviral drug resistance (e.g., acyclovir-resistant HSV).

Practice Questions: Viral Infections in Immunocompromised Hosts

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Flashcards: Viral Infections in Immunocompromised Hosts

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Which herpesvirus groups are associated with pityriasis rosea?_____

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Which herpesvirus groups are associated with pityriasis rosea?_____

HHV 6, HHV 7, HHV 8, HSV 2

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