The most common means of HIV transmission worldwide is through

• A. Intimate sexual contact.
• B. Blood transfusions.
• C. Sharing of needles in intravenous drug use.
• D. Transplacental passage of the virus.

Answer: (A)

HIV spreads most often through intimate sexual contact. This route exposes large numbers of people to infected fluids—semen and vaginal secretions—in a way that allows the virus to enter the body through mucous membranes or tiny cuts. Even though the per-exposure risk is relatively modest, the sheer frequency of sexual encounters worldwide makes this the dominant way the virus is transmitted globally.

Blood transfusions become risky mainly in areas without strict screening; with modern testing, they contribute far fewer new infections than sexual contact. Sharing needles in intravenous drug use is a major route in certain populations or regions, but it does not account for the majority of transmissions worldwide. Transplacental transmission occurs from mother to child during pregnancy, birth, or breastfeeding, but it represents a smaller share of total transmissions, though it remains an important prevention focus in perinatal care.