Transmission of HIV

HIV can only be transmitted under specific conditions that allow contact with infected body fluids, including blood, semen, vaginal secretions, and breast milk.

Transmission of HIV occurs through sexual intercourse with an infected partner, exposure to HIV-infected blood or blood products, and perinatal transmission during pregnancy, at the time of delivery, or through breastfeeding.

HIV-infected individuals can transmit HIV to others within a few days after becoming infected. After that, the ability to transmit HIV is lifelong.  Duration and frequency of contact, volume of fluid, virulence and concentration of the organism, and host immune status all affect whether infection is established after an exposure.

Sexual Transmission.

Unprotected sexual contact with an HIV-infected partner is the most common mode of transmission. Sexual activity provides an opportunity for contact with semen, vaginal secretions, and/or blood, all of which have lymphocytes that may contain HIV.

Although men who have sex with men (MSM) still account for most cases of HIV . The riskiest sexual activity is unprotected anal intercourse. 

Contact with Blood and Blood Products.

HIV can be transmitted during exposure to blood through drug-using equipment. Used equipment may be contaminated with HIV and other blood-borne organisms, and sharing that equipment can result in disease transmission.

Perinatal Transmission.

Perinatal transmission is the most common route of infection for children. Transmission from an HIV-infected mother to her infant can occur during pregnancy, at the time of delivery, or after birth through breastfeeding. On average, 25% of infants born to untreated HIV-infected women will be born with HIV. This means that 75% of these infants would not have been infected even without treatment.