What are the top two causes of AIDS?

AIDS is caused by the human immunodeficiency virus (HIV). HIV is transmitted through contact with infected blood, semen, vaginal fluids, rectal fluids, and breast milk. The top two causes of HIV infection are:

* Unprotected sex: This is the most common way for HIV to be transmitted. When someone who is HIV-positive has unprotected sex with someone who is HIV-negative, the virus can be passed from one person to the other.

* Sharing needles: Sharing needles or other drug paraphernalia with someone who is HIV-positive can also lead to HIV infection. This is because HIV can live in blood outside the body for up to a week.