By having sex. You may become infected if you have anal, vaginal or oral sex with an infected partner whose semen,blood, or vaginal secretions enter your body.
From blood transfusions. In some cases, the virus may be transmitted through blood transfusions.
By sharing needles. HIV can be transmitted through syringes and needles contaminated with HIV infected blood.
During pregnancy or delivery or through breast-feeding.There is high chance that HIV Infected mothers can infect their babies during pregnancy or delivery or through breast-feeding. Proper treatment should be given to mother during pregnancy so that the baby will not get infected to HIV virus.