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HIV and STIs — KMTC Medicine Study Notes

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PART 1: HIV/AIDS

1. Overview & Epidemiology

• ~39 million people worldwide living with HIV (2022); ~630,000 deaths/year
• Sub-Saharan Africa bears ~67% of global HIV burden — Kenya included
• ART has transformed HIV from a fatal disease into a manageable chronic illness
• UNAIDS 95-95-95 targets (by 2030): 95% know their status → 95% on ART → 95% virally suppressed
• Five countries already achieved this: Botswana, Eswatini, Rwanda, Tanzania, Zimbabwe
• First-line ART in low/middle-income countries now costs <$45/patient/year (down from >$10,000 in 2000)

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2. The Virus — Structure & Classification

• HIV-1 (predominant globally) and HIV-2 (West Africa)
• Retrovirus — carries RNA genome; uses reverse transcriptase to make DNA
• Key surface glycoproteins: gp120 (binds CD4) and gp41 (membrane fusion)
• Core contains: RNA genome, reverse transcriptase, integrase, protease

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3. Pathogenesis

Entry & Transmission

• Sexual contact (most common)
• Mother-to-child (vertical) — antenatal, intrapartum, breastfeeding
• Contaminated needles/blood products
• Healthcare worker needlestick

Mechanism of CD4+ T-cell Destruction

1. HIV binds CD4 receptor + co-receptor (CCR5 on macrophages/memory T cells; CXCR4 on T cells)
2. Virus enters, reverse transcriptase converts RNA → DNA
3. Viral DNA integrates into host genome (provirus) via integrase
4. Cell machinery produces new virions; protease cleaves viral precursors
5. Infected CD4+ T cells are killed — progressive immunodeficiency

Cellular Reservoirs

CNS Involvement

Natural History of HIV Infection

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4. WHO Clinical Staging

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5. AIDS-Defining Opportunistic Infections

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6. Diagnosis of HIV

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7. Antiretroviral Therapy (ART)

Drug Classes & Mechanism

Kenya First-Line ART (Adults)

• Alternative: AZT + 3TC + EFV (if DTG unavailable or contraindicated)

When to Start ART

• All HIV-positive patients regardless of CD4 count — "Treat All" policy (WHO 2015 onward)
• Start as early as possible after diagnosis and readiness counseling
• In OI co-infection: treat OI first, then start ART (except TB — start ART within 2–8 weeks)

Monitoring on ART

• Viral load at 6 months, 12 months, then annually — goal: undetectable
• CD4 count — baseline, then annually
• Clinical monitoring: weight, symptoms, drug toxicity

Common ART Side Effects

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8. Prevention of Mother-to-Child Transmission (PMTCT)

• Without intervention: transmission rate ~25–45%
• With full ART: transmission <1–2%
• Kenya PMTCT protocol: All HIV+ pregnant women start lifelong ART (Option B+)
• Infant receives NVP syrup for 6 weeks (prophylaxis)
• EID at 6 weeks (DNA PCR)
• Exclusive breastfeeding for 6 months if mother is on ART with VL suppressed

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9. Pre-Exposure Prophylaxis (PrEP) & Post-Exposure Prophylaxis (PEP)

• Preferred: TDF + 3TC + DTG × 28 days
• Must start as soon as possible; not effective if started >72 hours post-exposure

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10. HIV/TB Co-infection

• HIV is the strongest risk factor for TB reactivation
• CD4 <50: start ART within 2 weeks of TB treatment
• CD4 >50: start ART within 8 weeks
• Monitor for IRIS
• Cotrimoxazole Preventive Therapy (CPT): TMP-SMX daily — all HIV+ patients with CD4 <200 (prevents PCP, toxoplasma, isospora)

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PART 2: SEXUALLY TRANSMITTED INFECTIONS (STIs)

1. Overview

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2. Common STIs — Summary Table

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3. Syndromic Management (KMTC/Kenya Focus)

Urethral Discharge Syndrome (Male)

• Likely: Gonorrhea + Chlamydia
• Tx: Ceftriaxone 500 mg IM + Azithromycin 1g PO (single dose)
• Partner notification and treatment

Vaginal Discharge Syndrome

• Likely: Trichomoniasis + BV (± Gonorrhea/Chlamydia in high-risk)
• Tx: Metronidazole 2g stat (or 400 mg BD × 7 days)
• If cervicitis signs: add Ceftriaxone + Azithromycin

Genital Ulcer Syndrome

• Likely: Syphilis + Chancroid (± Herpes)
• Tx: Benzathine Penicillin 2.4 MU IM + Azithromycin 1g stat
• If herpes suspected: add Acyclovir

Lower Abdominal Pain in Women (PID)

• Likely: Gonorrhea + Chlamydia + Anaerobes
• Outpatient Tx: Ceftriaxone 500 mg IM stat + Doxycycline 100 mg BD × 14 days + Metronidazole 400 mg BD × 14 days
• Inpatient Tx: Cefoxitin/Clindamycin + Gentamicin IV

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4. Pelvic Inflammatory Disease (PID) — Detail

• Inflammation of upper female genital tract: endometritis, salpingitis, tubo-ovarian abscess, pelvic peritonitis
• Caused by ascending infection from cervix
• Pathogens: N. gonorrhoeae, C. trachomatis → secondary invasion by Bacteroides, Gram-negatives, Group B Strep
• Minimum clinical criteria: lower abdominal tenderness + adnexal tenderness ± cervical motion tenderness
• Complications:
  • Tubal-factor infertility: 7% after 1 episode, 28% after ≥3 episodes
  • Ectopic pregnancy risk ↑ 7–10 fold
  • Chronic pelvic pain
  • Tubo-ovarian abscess (Fitz-Hugh–Curtis if perihepatitis)

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5. Neonatal Infections from STIs

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6. HIV and STIs — Interconnection

• STIs increase HIV transmission 2–5 fold — ulcerative STIs (syphilis, herpes, chancroid) disrupt mucosal barriers; inflammatory STIs recruit CD4+ T cells to genital mucosa
• HIV+ patients have more severe/atypical STI presentations
• STI treatment is a key HIV prevention strategy
• All patients diagnosed with an STI should be offered HIV testing
• Concurrent testing for Gonorrhea, HIV, and Syphilis recommended with any Chlamydia diagnosis

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7. STI Prevention (5 Cs)

1. Counseling — risk reduction, behaviour change
2. Condom use — male and female condoms
3. Contact tracing — partner notification and treatment
4. Compliance — adherence to full treatment courses
5. Check-up — follow-up and screening (test of cure for Gonorrhea)

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8. Special Populations

• Tetracyclines and quinolones are contraindicated
• Chlamydia: Azithromycin 1g stat (preferred over doxycycline)
• Gonorrhea: Ceftriaxone 250 mg IM
• Syphilis: Benzathine Penicillin (no alternative — desensitize if allergic)
• Screen for: HIV, Syphilis (RPR), Hepatitis B at first ANC visit

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9. Key Investigations Summary

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Quick Revision — High-Yield Points for KMTC Exams

📌 HIV enters via CD4 receptor + CCR5/CXCR4 co-receptors 📌 AIDS defined as CD4 <200/μL OR presence of an AIDS-defining illness 📌 First-line ART in Kenya: TDF + 3TC + DTG (once daily) 📌 PEP must start within 72 hours of exposure 📌 Window period = time between infection and detectable antibodies (~3–12 weeks) 📌 Most common STI worldwide: Chlamydia trachomatis 📌 Painless chancre = Primary syphilis; Palm/sole rash = Secondary syphilis 📌 PID minimum criteria: lower abdominal + adnexal tenderness 📌 Syndromic management: treat without waiting for lab results 📌 STIs increase HIV transmission 2–5 fold 📌 PMTCT reduces MTCT from ~35% to <2% with full ART

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