SHM Converge Scientific Abstract ePoster Gallery-Rocky Mountain Spotted Fever Without the Spot: A Rare Atypical Presentation

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This case report describes a rare atypical presentation of Rocky Mountain Spotted Fever (RMSF) in a 79-year-old man with coronary artery disease who presented with one week of fever, chills, generalized weakness, myalgias, headache, cough, and diarrhea, but notably no rash. On examination he was febrile but otherwise stable and lacked the classic skin findings often associated with RMSF.<br /><br />Initial workup showed severe thrombocytopenia, elevated liver enzymes, acute kidney injury, and markedly increased inflammatory markers, including CRP and ferritin. Imaging was unremarkable. When he developed encephalopathy, lumbar puncture was performed, but cerebrospinal fluid studies were negative for infection. A respiratory viral panel was positive for human metapneumovirus, but tick-borne testing later revealed an RMSF IgG titer of 1:256.<br /><br />He was started on doxycycline, with subsequent clinical improvement. His fever and encephalopathy resolved, and his platelet count, inflammatory markers, transaminases, and renal function gradually improved.<br /><br />The report emphasizes that RMSF can present without rash, making diagnosis more difficult and delaying treatment. In patients with fever, thrombocytopenia, transaminitis, renal dysfunction, and systemic inflammation—especially in endemic areas or with possible tick exposure—RMSF should remain on the differential diagnosis. The authors stress that serologic testing is helpful, but treatment with doxycycline should not be delayed when suspicion is high, as early therapy is essential to reduce morbidity and mortality.

Asset Subtitle

Zhong Zheng

Meta Tag

Author List Chen Rong Phang, Heyue Du, Zhong Zheng

Category Clinical Vignettes

Concept Rocky Mountain Spotted Fever

Concept Doxycycline

Concept Multiorgan Dysfunction

Concept Empiric Treatment

Concept Fever

Distinguished Non-Finalist

Presenter Organization TidalHealth

Presenting Author Zhong Zheng

Track Adult

Keywords

Rocky Mountain Spotted Fever

RMSF

atypical presentation

no rash

thrombocytopenia

transaminitis

acute kidney injury

encephalopathy

doxycycline

tick-borne infection

Rocky Mountain Spotted Fever

Doxycycline

Multiorgan Dysfunction

Empiric Treatment

Fever