The human immunodeficiency virus, or HIV, is transmitted through sex with an infected person, blood transfusions and sharing needles. A mother with HIV can pass the virus to her child through pregnancy and breastfeeding.
The Mayo Clinic states that HIV is transmitted through vaginal secretions, infected blood and semen. It cannot be transmitted through activities such as sharing a cup, hugging, and kissing. It also cannot be transmitted through insect bites and water. The risk of contracting HIV is increased for people who have unprotected sex or who have recently had a sexually transmitted disease. Men who engage in sexual intercourse with other men and people with multiple sex partners are also at an increased risk.
One of the best ways to prevent the transmission of HIV is to practice safe sex. Safe sex practices include using a latex condom and dental dam during sex. People with an increased risk of contracting HIV can take the drug Truvada. The drug has to be used with safe sex practices to be most effective. Drug users can avoid transmission of the virus by not injecting drugs or by avoiding sharing paraphernalia such as needles. Some clinics have programs that will exchange dirty equipment for clean versions, to help reduce the spread of the virus.
A person can be infected with HIV for years before it becomes AIDS. People are considered to have AIDS when their CD4 white-blood cell count drops below 200 or they contract an AIDS-defining illness such as tuberculosis or pneumocystis pneumonia.