HIV infects immune system cells called CD4 cells, or T-cells. HIV works to destroy those cells, lowering the overall immune system to the point where infections and diseases run rampant, and HIV infection turns into AIDS. The AIDS diagnosis comes when T-cells drop below a count of 200.

Statistics

More than 1 million people in the United States older than age 13 are estimated to be infected with HIV, with nearly 11 percent of them unaware of their infection, according to statistics from the Centers for Disease Control and Prevention. The majority of the afflicted are bisexual and gay men who have sex with other men, with black men being the largest group.

Unfortunately, despite massive education efforts, the total number of people with HIV infections is increasing, even though annual numbers remain relatively stable. There are an estimated 50,000 new infections each year, with more than 25,000 people developing AIDS. There have been close to 1.2 million people in the United States diagnosed with AIDS since the infection was first discovered. An estimated 658,000 people with an AIDS diagnosis have died in the United States. However, not all of them necessarily died from AIDS and may have passed away from unrelated causes, accidents or suicide.

The Origins of HIV

It's believed that HIV originated in Africa via animal-to-human transmission when hunters would seek "bush meat," or that of chimpanzees, to eat.

HIV/AIDS surged in the 1980s among gay men and intravenous drug users, primarily, and was largely ignored for several years until it affected other segments of the population, including heterosexual people and children. It is now known that bodily fluids such as semen and blood transmit the virus, which made it difficult to cross oceans when jet travel was not common.