Final answer:
HIV can be transmitted through direct contact with infected body fluids like blood, semen, or breast milk. Sexual contact and the use of contaminated needles are common modes of HIV transmission. Blood transfusions used to transmit HIV, but this is no longer the case due to improved screening.
Step-by-step explanation:
HIV is transmitted through direct contact of mucous membranes or body fluids such as blood, semen, or breast milk. It can be transmitted through sexual contact or the use of contaminated hypodermic needles. It can also be transmitted from an infected mother's blood during late pregnancy or childbirth or through breast milk after birth. Blood transfusions used to transmit HIV in the past, but this is no longer the case because donated blood is now screened for HIV.