| Rocky Mountain Spotted Fever |
| Introduction |
Etiological agent = Rickettsia rickettsii
Like Lyme disease and ehrlichiosis, Rocky Mountain spotted fever (RMSF) is a tickborne disease that is not directly transmitted from animals to humans. But by harboring infected ticks, domestic animals may increase the chances for human exposure.
Contrary to its name, the majority of cases of RMSF occur east of the Rocky Mountain states, particularly in the Southeastern and South Central regions of the U.S.
Dermacentor variabilis and D. andersonii ticks are the major vectors that transmit R. rickettsii in the United States, and the organism is transmitted both transstadially and transovarially by these ticks. As such, ticks themselves can serve as a reservoir of the organism, along with rodents and small mammals. (Click here for a photo comparing Dermacentor and Ixodes ticks)
The pathogenesis of RMSF involves replication of the organism in endothelial cells, leading to vasculitis, increased vascular permeability and petechiae. This may progress to consumptive coagulopathy and shock.
| RMSF topics |
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