## HIV Transmission Routes: Global Epidemiology **Key Point:** Sexual transmission (both heterosexual and MSM) accounts for approximately 95% of new HIV infections globally, making it the dominant transmission route worldwide. ### Breakdown of Global HIV Transmission Routes | Transmission Route | Proportion of New Infections | Geographic Variation | |---|---|---| | Sexual transmission (heterosexual + MSM) | ~95% | Highest in Sub-Saharan Africa, South Asia, Latin America | | Intravenous drug use | ~3–5% | Concentrated in Eastern Europe, Central Asia, parts of Asia | | Mother-to-child transmission | ~1–2% | Declining with PMTCT programs | | Healthcare-related (needlestick) | <0.1% | Occupational risk ~0.3% per exposure | | Blood transfusion | <0.1% | Rare in countries with screening | **High-Yield:** This distribution is fundamental to understanding HIV prevention strategies and is heavily tested in epidemiology sections. ### Clinical Context for India In India, the primary transmission routes are: 1. Heterosexual transmission (~87% of cases) 2. Intravenous drug use (~5–10%, especially in northeast India) 3. Mother-to-child transmission (~2–3%) 4. MSM transmission (~3–5%) **Mnemonic:** **SIM** — Sexual transmission, Intravenous drug use, Mother-to-child transmission. Remember: Sexual >> IV >> MTCT >> Occupational. **Clinical Pearl:** Prevention strategies must prioritize sexual transmission reduction through condom promotion, PrEP, and treatment as prevention (U=U: undetectable = untransmittable). [cite:UNAIDS Global HIV Statistics 2023, Park 26e Ch 8]
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