Human Papillomavirus Infections

Human Papillomavirus Infections

Human Papillomavirus Infections

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Human Papillomavirus Infections - Viral Villains

  • Small, non-enveloped, circular dsDNA virus; Icosahedral capsid; >200 types identified.
  • Epitheliotropic: infects basal keratinocytes of skin & mucosa.
  • High-risk (oncogenic) types: 16, 18, 31, 33, 45, 52, 58.
    • Key oncogenes: E6 (degrades p53), E7 (inactivates pRb).
  • Low-risk (genital warts/condyloma acuminata) types: 6, 11.
  • Transmission: Primarily sexual contact; also direct/indirect contact, vertical.

    ⭐ HPV types 16 and 18 are responsible for approximately 70% of all cervical cancers worldwide. HPV Virion and Genome Structure

Human Papillomavirus Infections - How HPV Invades

  • Entry: Via microabrasions to basal keratinocytes.
  • Oncogenes & Effects:
    • E6: Degrades p53 → ↓Apoptosis.
    • E7: Inactivates pRb → ↑Cell Cycle Progression.
  • Outcome: Malignant potential.

⭐ HPV 16 & 18 (high-risk) DNA integration → persistent E6/E7 → cancer.

Human Papillomavirus Infections - Warts to Worse

  • Double-stranded DNA virus; >150 types. Transmission: direct/sexual contact, fomites.
  • Clinical Spectrum:
    • Benign: Cutaneous warts (verruca vulgaris, plana), anogenital warts (condylomata acuminata; HPV 6, 11), laryngeal papillomas.
    • Malignant transformation: Cervical (HPV 16, 18, 31, 33), anal, penile, vulvovaginal, oropharyngeal cancers.
  • Diagnosis: Clinical; biopsy shows koilocytes (perinuclear halo).
  • Management: Topical (salicylic acid, podophyllin), cryotherapy, imiquimod, surgical excision.
  • Prevention: HPV vaccination (quadrivalent/nonavalent). Koilocytes in cervical smear

⭐ HPV types 16 and 18 account for approximately 70% of all cervical cancers globally and are considered high-risk types.

Human Papillomavirus Infections - Spotting the Signs

  • Clinical Lesions:
    • Anogenital warts (condylomata acuminata): cauliflower-like growths.
    • Cutaneous warts (verrucae): common, plantar, flat.
    • Recurrent respiratory papillomatosis (laryngeal).
  • Diagnostic Clues:
    • Visual inspection.
    • Acetowhitening: 3-5% acetic acid application reveals white lesions.
    • Cytology (Pap smear): koilocytic atypia.
    • Colposcopy: for abnormal cervical findings.
    • HPV DNA testing: identifies oncogenic types (e.g., 16, 18). HPV Infections: Background, Symptoms, Causes, Treatment

⭐ Koilocytes (cells with perinuclear halo and nuclear atypia) are pathognomonic for HPV cytopathic effect seen in Pap smears or biopsies.

Human Papillomavirus Infections - Managing Manifestations

  • General Options: Watchful waiting; Medical (patient-applied: Imiquimod, Podophyllotoxin; provider-applied: TCA, Cryotherapy); Surgical (Excision, Laser).
  • Anogenital Warts (Condyloma Acuminata):
    • Patient-applied: Imiquimod 5% cream, Podophyllotoxin 0.5% solution.
    • Provider-administered: Cryotherapy, Trichloroacetic acid (TCA) 80-90%, Surgical excision.
  • Cutaneous Warts (Verruca Vulgaris): Salicylic acid, Cryotherapy.
  • Cervical Intraepithelial Neoplasia (CIN): Observation for low-grade; LEEP/LLETZ or conization for high-grade.

⭐ Most anogenital warts are caused by low-risk HPV types 6 and 11.

Human Papillomavirus Infections - Vaccine Victories

  • Goal: Prevent HPV infection & related cancers (cervical, anogenital, oropharyngeal).
  • Vaccines (L1 VLP-based):
    • Bivalent (Cervarix): HPV 16, 18.
    • Quadrivalent (Gardasil): HPV 6, 11, 16, 18.
    • Nonavalent (Gardasil 9): HPV 6, 11, 16, 18, 31, 33, 45, 52, 58.
  • Schedule (IAPCOI guidelines):
    • Age 9-14 yrs: 2 doses (0, 6 months).
    • Age ≥15 yrs: 3 doses (0, 1-2, 6 months).
  • Efficacy: High for targeted types; reduces warts, precancers, cancers.
  • Screening (e.g., Pap smear) remains crucial post-vaccination. and dosing schedule)

⭐ Gardasil 9 (Nonavalent vaccine) protects against HPV types causing approximately 90% of cervical cancers worldwide.

High‑Yield Points - ⚡ Biggest Takeaways

  • HPV, a DNA virus, is the most common STI globally.
  • High-risk types (16, 18) cause most cervical cancers; low-risk types (6, 11) cause genital warts.
  • Koilocytes (perinuclear halo) on Pap smear are pathognomonic.
  • HPV vaccines (e.g., Gardasil-9) offer primary prevention against cervical cancer.
  • Persistent high-risk HPV infection is key for cervical carcinogenesis.
  • Screening includes Pap smear and HPV DNA testing for early detection of cervical changes.

Practice Questions: Human Papillomavirus Infections

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