Unprotected sexual intercourse (vaginal and anal): Unprotected sex means having anal or vaginal intercourse and oral sex without using a condom. The virus may enter through body fluids, semen, tip of penis or mucus membrane within the vagina, however, HIV cannot be transmitted through sweat and saliva.
Mother-to-child: HIV and Sexually Transmitted Infections (e.g. syphilis, genital warts) can be transmitted from an infected woman to her child during pregnancy, childbirth (also called labour and delivery), or breastfeeding.
Blood and blood products: HIV can be transmitted through contact with blood, e.g. blood transfusion, reusing or sharing of needle, razor blade, or other sharp objects with an infected person. Even if a needle or a sharp object appears to be clean to the naked eyes, it can still contain bacteria and viruses. Therefore, we should never reuse a needle or syringe . And if it is necessary to make wound on body such as piercing, reliable professionals should be asked to handle the related work.
