Rocky Mountain Spotted Fever

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Presentation :

• Initially presents with non-specific febrile illness, followed 3-5 days later by rash
• Rash evolves from a macular eruption localized to the ankles or wrists, with central spread and progression to petechiae or purpura
  • Lesions are found on the palms and soles in as many as 50% of patients; the face is generally spared.
  • Purpura fulminans may occur and result in loss of digits or limbs.
• Up to 30% of patients present with meningoencephalitis.

Pathophysiology :

• Caused by Rickettsia rickettsii
• Transmitted by American dog tick (Dermacentor variabilis), the Rocky Mountain wood tick (Dermacentor andersoni), or the brown dog tick (Rhipicephalus sanguineus)

Diagnostic Testing:

• Immunohistochemical analysis of skin biopsy samples may be diagnostic
• Serology is insensitive during acute illness, and testing convalescent serum is often needed to confirm the diagnosis.

Treatment :

• Doxycycline should be given empirically when SFR is suspected because treatment delay is associated with more severe disease and increased mortality.

Prognosis:

References:

• MKSAP
• StatPearls