HIV (human immunodeficiency virus) is more frequently transmitted through unprotected sex or sharing contaminated needles. Transmission from mother to fetus or through blood products has significantly declined in the United States.
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.