This is an engorged deer tick (Ixodes dammini) embedded in the skin of a human host. In the United States, these ticks are the primary source of Lyme disease. (Image courtesy of the Centers for Disease Control and Prevention and M. Fergione.)
Review Date 1/31/2018
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.