Sexual Contact:
- Vaginal/Anal Sex: 1–3 per 1,000 exposures (higher for receptive anal sex).
- Oral Sex: <1 per 1,000 exposures (low risk due to lower viral load in saliva).
- Rationale: Transmission depends on viral load, presence of STIs, and mucosal damage.
- Blood/Needle Exposure:
- Needle Stick: ~0.3% per exposure (higher for larger volumes).
- Blood Transfusion: Near 0% (due to screening).
- Mother-to-Child:
- Perinatal: 15–30% without ART; <1% with ART + PMTCT.
- Breastfeeding: 5–20% without ART; ~1% with ART.
- Other Routes:
- Kissing: No documented cases (saliva has low viral load, no blood exchange).
- Casual Contact (Hugging, Sharing Utensils): No risk (virus unstable outside body).
- Key Factors:
- Viral load (higher = increased risk).
- Presence of STIs (e.g., HSV, syphilis) disrupts mucosal barriers.
- ART reduces transmission risk by ~96% (UNAIDS, 2023).
Sources:
- WHO (2023), CDC (2022), UNAIDS (2023) guidelines.