How common is HIV (human immunodeficiency virus) infection?

While human immunodeficiency virus (HIV) -- the infection that causes or is presumed to cause acquired immunodeficiency syndrome (AIDS) -- has traditionally been associated with gay men and intravenous drug users, the incidence of the disease is growing in other sectors of the population. Half a million to a million and a half people in the United States are infected with HIV, with six times as many men being infected as women. Infection rates are higher in the African-American and Latino communities, presumably because of other associated risk factors, such as higher rates of drug use. And 34 to 43 million people are infected with HIV worldwide. It is a true epidemic.