How is it true that HIV can be passed between individuals?

HIV is primarily transmitted through specific routes that involve the exchange of bodily fluids such as blood, semen, vaginal fluids, rectal fluids, and breast milk. Direct blood exposure, as stated in the chosen answer, is one of the primary means of transmission. This can occur through activities such as sharing needles among intravenous drug users or through transfusions of infected blood.

The other routes mentioned do not facilitate the transmission of HIV. Casual contact, sharing drinks, or skin contact do not provide the conditions necessary for HIV to be transmitted. The virus cannot survive long outside the human body, and it does not spread through air, water, or casual touch, which are common misconceptions. Understanding these transmission routes is crucial for prevention and for educating others about how HIV spreads.