Introduction:
Tickborne disease occurs worldwide with recent recognition of changes in tick vector distributions. Rocky Mountain Spotted Fever (RMSF) is already widespread across the United States; however, it is being monitored for introduction to non-endemic areas.
Clinical Findings:
A 65-year-old male with a history of psoriatic arthritis on adalimumab and local tick exposures but no known recent bites presented to the emergency department with fevers, myalgias, arthralgias, and a maculopapular rash of unclear etiology. Initial testing showed transaminitis, worsened chronic thrombocytopenia, and slight neutropenia with absolute neutrophil count 2,330 (reference value: 2,400-7,600 cells per µL); however, he was stable and his tick panel including Lyme, anaplasma, babesia, and ehrlichia was negative so he was discharged.
Diagnoses, Therapeutics, and Outcomes:
The patient was then evaluated in clinic and found to have improving symptoms but worsening transaminitis. He was empirically started on doxycycline, and the same tick panel was repeated which resulted negative. Abdominal ultrasound, and viral serologies for Hepatitis B and C, Human Immunodeficiency Virus, Cytomegalovirus, Epstein-Barr Virus were negative. His Spotted Fever Group IgG then resulted positive and he completed empiric treatment with resolution of his symptoms and lab abnormalities. The case was reported to the state of Maine Center of Disease Control and Prevention.
Conclusion:
This case does not meet requirements for diagnostic confirmation of RMSF, but illustrates the diagnostic considerations for tickborne febrile illness in Maine
