Rocky Mountain Spotted Fever Presenting as an Ischemic Stroke: A Rare Manifestation.

Rocky Mountain spotted fever (RMSF) is among the most severe tick-borne rickettsial infections encountered in the United States. Its presentation ranges from the classic triad of fever, headache, and rash to central nervous system (CNS) conditions, including meningitis, encephalitis, and seizures. Notably, RMSF presenting as an ischemic stroke due to CNS vasculitis is rare, which can prove fatal if recognition is delayed.We present the case of a woman in her 50s with a history of well-controlled diabetes mellitus type 2 and hypertension, who presented with fever, chills, body aches, and rash. She developed a headache and confusion. Routine laboratory tests showed thrombocytopenia, hyponatremia, and transaminitis. Brain magnetic resonance imaging (MRI) with and without gadolinium demonstrated scattered punctate foci of restricted diffusion throughout both cerebral hemispheres, consistent with acute lacunar infarcts involving multiple vascular territories, raising concern for vasculitis. Initial RMSF immunoglobulin G (IgG) was negative, but repeat testing showed a greater than fourfold elevation of IgG level, along with a positive plasma microbial cell-free DNA assay (Karius Inc., Redwood City, California, United States) for Rickettsia rickettsii. She was treated successfully with two weeks of oral doxycycline. This case highlights the importance of considering RMSF as one of the differential diagnoses when there is neurovascular involvement in a suspected tick-borne illness, especially in endemic areas. Early recognition and prompt treatment are essential to limit neurovascular injury and improve clinical outcomes.