HIV and STIs

HIV Pathogenesis - Viral Villainy Unveiled

• HIV (retrovirus) infects CD4+ T-cells, macrophages, dendritic cells.
• Entry: gp120 binds CD4, then co-receptor (CCR5/CXCR4).
  • CCR5: Early infection, M-tropic strains.
  • CXCR4: Later infection, T-tropic strains, more cytopathic.
• Key Viral Enzymes: Reverse Transcriptase, Integrase, Protease.
• Replication Cycle:

• Outcome: Progressive ↓CD4 cell count, immune deficiency (AIDS).

⭐ HIV primarily utilizes the CCR5 co-receptor for entry in early infection (M-tropic), while CXCR4 usage (T-tropic) often emerges later and is associated with faster disease progression.

HIV Clinical & Diagnosis - Spotting The Enemy

• Acute Retroviral Syndrome (ARS): Flu/mono-like illness, high viral load (2-4 wks post-exposure).
• Clinical Latency: Asymptomatic, CD4 count gradually ↓.
• AIDS: CD4 < 200/µL or AIDS-defining illness (e.g., PCP, Kaposi Sarcoma). WHO Stage 4.
• Diagnosis:
  • Initial: 4th Gen (p24 Ag + HIV Ab) test. Window period: 2-6 weeks.
  • Confirmatory: HIV-1/HIV-2 differentiation assay or NAT.
  • NAT: Detects HIV RNA. Shortest window (1-4 weeks); for acute/neonatal Dx.

⭐ Most common opportunistic infection in HIV patients in India is Tuberculosis.

HIV Management - Fighting Back Smart

• ART Initiation: Start immediately for all PLHIV, regardless of CD4 count. Goal: viral suppression.
  • Monitoring: VL at 6, 12 months, then annually if suppressed (<50 copies/mL). CD4 if advanced/unsuppressed.
• PEP: ASAP (<2h ideal, max 72h) post-exposure; TDF + 3TC + DTG for 28 days.
• PrEP: Daily TDF/FTC or TDF/3TC for high-risk individuals.
• IRIS: Paradoxical worsening on ART; manage OI, continue ART.

⭐ Preferred first-line ART (NACO): Tenofovir (TDF) + Lamivudine (3TC) + Dolutegravir (DTG) as a fixed-dose combination.

Syphilis Spotlight - The Ancient Foe

• Agent: Treponema pallidum.
• Stages:
  • Primary: Painless chancre.
  • Secondary: Rash (palms/soles), condyloma lata.

    ⭐ Jarisch-Herxheimer Reaction: Post-Rx fever, chills, myalgia from treponemal lysis; self-limiting. Usually within 2-12h.

  • Latent: Asymptomatic (early/late).
  • Tertiary: Gummas, neurosyphilis, cardiovascular.
• Diagnosis: Screen: VDRL/RPR. Confirm: TPPA/FTA-ABS.
• Treatment (Penicillin G):
  • Early (1°, 2°, Early Latent): Benzathine 2.4 MU IM x1.
  • Late Latent/Tertiary: Benzathine 2.4 MU IM weekly x3.
  • Neurosyphilis: Aqueous Crystalline 18-24 MU IV daily x10-14d.

Gonorrhea & Chlamydia - Dual Trouble Duo

• Co-infection common. Dx: NAAT.
• Dual Tx for co-infection.

⭐ Fitz-Hugh-Curtis: perihepatitis (RUQ pain, violin-string adhesions) with PID (GC/CT).

Other STIs - Rapid Roundup Reel

• Trichomoniasis: T. vaginalis; frothy discharge, strawberry cervix. Metronidazole 2g PO single.
• HPV (Warts): HPV; condylomata acuminata. Podophyllin, Imiquimod.
• HSV (Herpes): HSV; painful vesicles. Acyclovir.
• Chancroid: H. ducreyi; painful ulcer. Azithromycin 1g PO single.
• LGV: C. trachomatis L1-L3; adenopathy. Doxycycline.

  ⭐ LGV: C. trachomatis L1-L3; pathognomonic "groove sign".

• Donovanosis: K. granulomatis; beefy-red ulcer, Donovan bodies. Azithromycin.

High‑Yield Points - ⚡ Biggest Takeaways

• HIV primarily targets CD4+ T-lymphocytes; HAART is crucial for management.
• Syphilis (Treponema pallidum) presents with a painless chancre; screen with VDRL/RPR, confirm with FTA-ABS/TPHA.
• Gonorrhea (Neisseria gonorrhoeae) shows Gram-negative diplococci; causes urethritis and cervicitis.
• Chlamydia (Chlamydia trachomatis) is often asymptomatic; can lead to PID and infertility.
• Genital Herpes (mainly HSV-2) is characterized by painful vesicular lesions.
• HPV serotypes 16 & 18 are linked to cervical cancer; 6 & 11 cause genital warts (condyloma acuminata).