Rocky Mountain Spotted Fever

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Rocky Mountain spotted fever facts

  • Close to 2,000 cases of Rocky Mountain spotted fever (RMSF) are reported in the United States each year.
  • RMSF is a potentially serious tick-borne disease that can cause fatalities, and it is the most common cause of fatal tick-borne diseases in the United States.
  • The incident of RMSF has increased from less than two cases per million people in the year 2000, to over six cases per million people in 2010.
  • Although RMSF cases have been reported throughout the United States, the highest incidence of cases in 2010 were in Arkansas, Delaware, Missouri, North Carolina, Oklahoma, and Tennessee.
  • RMSF is treatable with antibiotics, but it can have serious long-term effects and lead to death if not treated quickly and properly.

What is Rocky Mountain spotted fever?

Rocky Mountain spotted fever (RMSF) is a tick-borne disease caused by the bacterium Rickettsia rickettsii. This illness, which is found in North, Central, and South America, is transmitted via the bite of an infected tick. The illness affects the lining of blood vessels (causing a condition termed vasculitis), causing the blood vessels to leak, which ultimately can cause damage to nearly all internal organs.

What causes Rocky Mountain spotted fever?

RMSF is caused by Rickettsia rickettsii, a bacterium that is transmitted to humans via the bite of an infected tick. In the United States, these ticks include the Rocky Mountain wood tick (Dermacentor andersoni), American dog tick (Dermacentor variabilis), and brown dog tick (Rhipicephalus sanguineus).

The tick needs to bite humans and then attach itself for at least six to 10 hours for the transmission of the bacterium to occur, although transmission does not occur for up to 24 hours in some cases.

Medically Reviewed by a Doctor on 5/15/2014

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