The Changing Epidemic of HIV.

Now in its third decade, the epidemiology of human immunodeficiency virus (HIV) transmission in the United States has changed considerably since the epidemic began. Our increased understanding of the virus has fueled development of new treatments to prolong life, and research into a viable vaccine offers hope to those at risk in developed and less developed countries alike. In this review, we provide information about the current trends in HIV and Acquired Immune Deficiency Syndrome (AIDS) among those in the United States who are hardest hit by the epidemic. We also offer insights into and explanations of these changes; update the epidemiology of HIV subtypes and antiretroviral resistance; and describe current strategies for HIV surveillance.