Rocky Mountain Spotted Fever (Legs)

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Rocky Mountain Spotted Fever (RMSF)

Rocky Mountain spotted fever (RMSF) is an acute febrile disease, initially recognized in the Rocky Mountain states, caused by Rickettsia rickettsii and transmitted by hard-shelled (ixodid) ticks. It occurs only in the Western Hemisphere. Anyone frequenting tick-infested areas is at risk for RMSF.

The onset of symptoms is abrupt, including headache, high fever, chills, muscle pain, and a subsequent rash. The rickettsiae grow within damaged cells lining blood vessels, which may become blocked by clots. Blood vessel inflammation (vasculitis) is widespread.

Early recognition of RMSF and prompt antibiotic treatment are critical to reducing mortality.

The disease was first described in 1899 by Edward Ernest Maxey, an ear, nose, and throat specialist. In 1906, pathologist Howard Taylor Ricketts demonstrated that it was transmitted by a tick bite. The causative agent was named Rickettsia rickettsii in his honor.

Rocky Mountain spotted fever is also known as spotted fever, tick fever, or tick typhus.

Image Source: Color Atlas of Pediatric Dermatology, Samuel Weinberg, Neil S. Prose, Leonard Kristal, Copyright 2008, 1998, 1990, 1975, by the McGraw-Hill Companies, Inc. All rights reserved.
Text Source: MedTerms™ Medical Dictionary by MedicineNet, Inc.