Disease
Rocky Mountain spotted fever
Tick-borne rickettsial vasculitis with rash
High-yield clue
Fever, headache, and a rash starting on wrists/ankles then spreading to palms and soles is the classic RMSF clue.
Overview
A tick-borne rickettsial illness caused by Rickettsia rickettsii that infects small-vessel endothelium, studied for its fever plus centripetal petechial rash. It matters as a rapidly progressive vasculitic syndrome where the rash may appear late.
Classification
- Tick-borne rickettsial syndrome
- Small-vessel vasculitis mechanism
- Zoonosis via Dermacentor/Rhipicephalus ticks
- Region-linked (south-central/southeastern U.S.) framing
Lab & identification clues
- Rash begins wrists/ankles, spreads to palms/soles vocabulary
- Rash often appears days after fever (may be absent early) concept
- Petechial progression signaling severe disease term
- Thrombocytopenia and hyponatremia lab associations
Associations
- Transmitted by dog/wood ticks (Dermacentor, Rhipicephalus)
- Peak in spring-summer tick season
- At-risk framing: outdoor/dog exposure in endemic states
- Endothelial infection causing increased vascular permeability
Commonly confused with
- Lyme disease
- Meningococcemia
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.