HIV attacks and destroys a type of white blood cell called a CD4 cell. This cell's main function is to fight disease. When a person's CD4 cell count gets low, they are more susceptible to illnesses.
A person gets HIV when an infected person's body fluids (blood, semen, fluids from the vagina or breast milk) enter his or her bloodstream. The virus can enter the blood through linings in the mouth, anus or sex organs (the penis and vagina), or through broken skin.
The most effective treatment for human immunodeficiency virus (HIV) is highly active antiretroviral therapy (HAART) - a combination of several antiretroviral medications that aims to control the amount of virus in your body. Other treatments include keeping your immune system strong, taking medications as prescribed, and monitoring your CD4+ (white blood cells) counts to slow the multiplication of the virus in your body.