HIV (human immunodeficiency virus) is a viral infection that gradually destroys the immune system. Practicing effective safe sex methods significantly reduces the risk of disease transmission.
Review Date 6/5/2018
Updated by: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.