Scope of the HIV Epidemic

Scope of the HIV Epidemic

Although HIV was first identified in 1983, studies of previously stored blood samples indicate that the virus entered the U.S. population sometime in the late 1970s. In the United States, 1,106,391 cases of AIDS, and 597,499 deaths among people with AIDS had been reported to the Centers for Disease Control and Prevention (CDC) by the end of 2008 and 2007, respectively. Approximately 40,000 new HIV infections occur each year in the United States, 70 percent of them among men and 30 percent among women. Of the new infections, approximately 40 percent are from male-to-male contact, 30 percent from heterosexual contact, and 25 percent from injection drug use. Minority groups in the United States have also been disproportionately affected by the epidemic.

Worldwide, an estimated 33 million people were living with HIV as of December 2008, according to the Joint United Nations Programme on HIV/AIDS (UNAIDS). Through 2008, cumulative AIDS-associated deaths worldwide numbered more than 33 million. Globally, approximately 2.7 million new HIV infections and approximately 1.7 million AIDS-related deaths, including an estimated 280,000 children under 15 years old, occurred in the year 2008 alone.

HIV is a retrovirus

HIV belongs to a class of viruses called retroviruses. Retroviruses are RNA (ribonucleic acid) viruses, and to replicate (duplicate). they must make a DNA (deoxyribonucleic acid) copy of their RNA. It is the DNA genes that allow the virus to replicate.

Like all viruses, HIV can replicate only inside cells, commandeering the cell's machinery to reproduce. Only HIV and other retroviruses, however, once inside a cell, use an enzyme called reverse transcriptase to convert their RNA into DNA, which can be incorporated into the host cell's genes.