Rocky Mountain Spotted Fever (RMSF)

Rocky Mountain Spotted Fever



  • Rocky Mountain Spotted Fever is caused by Rickettsia rickettsia 

    Rocky Mountain Spotted Fever Tic Source:CDC

    Rocky Mountain Spotted Fever Tick

  • Prevalent in western states
  • A systemic small vessel vasculitis
  • Tick must attach and feed on blood for at least 4-6 hours to infect humans (less than Lyme disease which is minimum 24 hours)
  • Incubation period is 2-14 days
  • Thrombocytopenia develops in most patients
  • If untreated, the disease can persist for 3 weeks and affect CNS system, cardiac, pulmonary, renal & lead to DIC
  • Antibiotic therapy is the treatment
  • Doxycycline is the drug of choice



Clinical Signs & Symptoms

  • Signs & symptoms may not appear for up to 14 days
  • Flu-like symptoms: a severe headache, malaise, fever, chills nausea, vomiting, restlessness, insomnia, loss of appetite, abdominal pain
  • Photophobia
  • Conjunctival injection
  • Joint & muscle pain
  • Patient develops fever followed by a maculopapular rash (usually on 4th day)
  • Maculopapular rash (before 6th day of symptoms)
  • Rash spreads from wrists & ankles to trunk, neck, & face
  • Lesions become petechial if left untreated
  • The diagnosis of RMSF is made on clinical signs and symptoms, and can later be confirmed with specialized laboratory tests. Treatment should never be delayed pending laboratory tests or withheld on the basis of a negative finding for Rickettsia rickettsia




Diagnostic Tests

  • Weil-Felix test (detects antibodies that develop against Proteus antigens)
  • Gold standard serologic test for diagnosis of RMSF is the indirect immunofluorescence assay (IFA) with rickettsii antigen
  • PCR or immunohistochemical (IHC) staining can be performed on a skin biopsy taken from rash site
  • Thrombocytopenia


Differential Diagnosis

  • Typhoid fever
  • Atypical measles
  • Hypersensitivity reactions to drugs
  • Murine typhus
  • Meningococcemia
  • Meningococcal Infections
  • Pediatric Syphilis 


Treatment For RMSP


  • Doxycycline is the first line treatment for adults and children of all ages
  • Adults: 100 mg every 12 hours
  • Children under 45 kg (100 lbs): 2.2 mg/kg body weight given twice a day
  • Patients should be treated for at least 3 days after the fever subsides and until there is evidence of clinical improvement. Standard duration of treatment is 7-14 days
  • The use of doxycycline to treat suspected RMSF in children is standard practice recommended by the CDC and the AAP Committee on Infectious Diseases


Patient & Family Teaching

  • Wear protective clothing 
  • Avoid direct contact with ticks
  • Avoid brushy areas, high grass, wooded areas and leaf litter
  • Walk in the center of trails
  • Repel Ticks with DEET or Permethrin (use repellents that contain 20 to 30% DEET) 
  • May use other repellents registered by the Environmental Protection Agency (EPA)
  • If tick is found remove tick and notify health care provider immediately 
  • Shower after coming indoors 
  • Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body 
  • Check children for ticks under the arms, ears, belly button,knees, legs,waist, in hair
  • Examine clothing and pets
  • Tumble dry clothes in a dryer on high heat for 10 minutes to kill ticks on dry clothing after you come indoors
  • If clothing requires washing use hot water and tumble dry on high heat 



Center for Disease Control and Prevention (CDC) (n.d.). Public health image library (PHIL). Retrieved August 22, 2016, from

Centers for Disease Control and Prevention (CDC) (n.d.). Rocky mountain spotted fever (RMSF). Retrieved August 22, 2016, from

Dunphy, L.M., Winland-Brown, J. E. (2011).  Primary Care:  The Art and Science of Advanced Practice Nursing.  Philadelphia, PA.  F.A. Davis. 

Uphold, C.R., & Graham, M.V. (2013). Clinical guidelines in family practice. (5th ed.)      Gainesville, Fl.: Barmarrae Books, Inc.

Wolff, K., Johnson, R.A., SaaVedra, A. (2013). Fitzpatrick Color Atlas and Synopsis of   Clinical Dermatology (7th ed.). McGraw-Hill: New York

Boynton, R., Dunn, E.S., & Stephens, G.R. (2009). 6th edition.  Manual of Ambulatory Pediatrics.  Philadelphia:  Lippincott.