Different types of fleas prefer specific animals as hosts, but will infest humans if their specific hosts are unavailable. Fleas can carry plague and typhus. They are also thought to transmit several other diseases. (Image courtesy of the Centers for Disease Control and Prevention.)
Review Date 9/23/2019
Updated by: Jacob L. Heller, MD, MHA, Emergency Medicine, Emeritus, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.