Ticks are small, insect-like creatures that live in woods and fields. They can attach to people or animals as they brush past bushes, plants, and grass. Ticks can be fairly large, as big as a pencil eraser, or so small that they are almost impossible to see. While most ticks do not carry diseases, some ticks can cause Lyme disease, Rocky Mountain spotted fever, Colorado tick fever, and tularemia.
Review Date 3/15/2021
Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate 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.