Rocky Mountain spotted fever (RMSF)


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

The onset of symptoms is abrupt with headache, high fever, chills, muscle pain. and then a 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 is important in reducing mortality.

The first person to describe the disease was an ear, nose and throat specialist, Edward Ernest Maxey. Maxey reported the disease in 1899. Seven years later, a pathologist named Howard Taylor Ricketts showed that it was transmitted by a tick bite. The agent that causes the disease was named for him — Rickettsia rickettsii.

Rocky Mountain spotted fever is also called spotted fever, tick fever, and tick typhus.

Read Also:

  • Rocky Mountain wood tick

    A tick that can transmit R. rickettsii, the agent of Rocky Mountain spotted fever. This tick is found in the Rocky Mountain states and in southwestern Canada. The life cycle of this tick may require up to 2 to 3 years for completion. Adult ticks feed primarily on large mammals. Larvae and nymphs feed on […]

  • Rod

    A type of specialized light-sensitive cell (photoreceptor) in the retina of the eye that provides side vision and the ability to see objects in dim light (night vision). By contrast, the cones are the retinal photoreceptors that provide sharp central vision and color vision.

  • Rodbell, Martin

    Paul, Suzanne, Andrew, and Phillip. In 1954, Rodbell completed his doctoral thesis, under the direction of Donald Hanahan, on aspects of the metabolism of lecithin (a complex mixture of phospholipids) in the liver. In the fall of that year, Rodbell accepted a postdoctoral position as a research associate in biochemistry at the University of Illinois […]

  • Rodenticidal

    Capable of killing rats or other rodent pests or preventing them from damaging food, crops, etc.

  • Rodenticide

    A chemical or other agent used to destroy rats or other rodent pests or prevent them from damaging food, crops, etc. Rat poison is a familiar rodenticide.


Disclaimer: Rocky Mountain spotted fever (RMSF) definition / meaning should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. All content on this website is for informational purposes only.