Rocky Mountain Spotted Fever Symptoms, Causes, Treatment - What causes Rocky Mountain spotted fever? on MedicineNet

Rocky Mountain Spotted Fever (cont.)

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Medical Author:

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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What causes Rocky Mountain spotted fever?

RMSF is caused by a small bacterium known as Rickettsia rickettsii. R. rickettsii lives inside the cells that line the blood vessels of infected animals and humans.

The tick is the primary home or reservoir for R. rickettsii. Because ticks can also spread the organism to humans and other animals, they are sometimes referred to as vectors for transmission of RMSF. Several different types of ticks can carry R. rickettsii. For example, the American dog tick (Dermacentor variabilis) is the most common vector in the eastern, central, and Pacific U.S. In the West, the Rocky Mountain wood tick (Dermacentor andersoni) is the primary vector for RMSF. Ticks can pass the organism to their offspring, creating a new generation of infected ticks. Ticks can also be infected by feeding on an infected person or animal. Even in the woodlands and fields of high-risk areas, only a small proportion of ticks will carry R. rickettsii.