INTRODUCTION
Rocky Mountain spotted fever (RMSF) is a potentially lethal, but usually curable, tick-borne disease. RMSF occurs throughout the United States, Canada, Mexico, Central America, and in parts of South America. The etiologic agent, Rickettsia rickettsii, is a gram-negative, obligate intracellular bacterium causing a spectrum of disease ranging from mild to fulminant. Overall, mortality from RMSF has declined markedly, from 2.2 percent in 2000 to 0.3 percent in 2007 and has been mostly unchanged since that time, although mortality rates as high as 7 percent in some populations have been reported [1-3].The treatment of RMSF will be reviewed here. The basic biology of R. rickettsii, and the epidemiology, clinical manifestations, and diagnosis of RMSF are discussed separately. (See "Biology of Rickettsia rickettsii infection" and "Epidemiology, clinical manifestations and diagnosis of Rocky Mountain spotted fever".)
APPROACH
We recommend empiric therapy with doxycycline for patients with suspected RMSF, even if symptoms are mild. Early therapy is critical since a delay in treatment is associated with an increased risk of mortality.When to suspect RMSF — A diagnosis of RMSF should be suspected in patients who are from an endemic area (or have visited one within the past 14 days) if they:
●Present in the spring and summer months with fever and at least one of the following: headache, rash, constitutional symptoms, or laboratory abnormalities or thrombocytopenia and elevated liver functions tests. (See "Epidemiology, clinical manifestations and diagnosis of Rocky Mountain spotted fever", section on 'Clinical manifestations' and "Epidemiology, clinical manifestations and diagnosis of Rocky Mountain spotted fever", section on 'Laboratory findings'.)