Not the Cat's Fault

A 38-year-old woman from Corpus Christi, Texas presents to her primary care physician with a 10-day history of high fever, severe headache, and diffuse myalgias. She noticed a rash on day five of her illness that began as faint pink macules on her trunk and has since spread to her arms and legs. She works from home, has not traveled recently, and spends most of her time indoors with her three cats, which have outdoor access. She reports no tick bites. She brings in a small insect she found crawling on one of her cats, shown below.

On examination, temperature is 39.4°C, heart rate 102, blood pressure 114/72 mmHg. She appears fatigued and uncomfortable. There is a maculopapular rash over the trunk and proximal extremities, sparing the palms, soles, and face. No eschar is identified. No lymphadenopathy. The remainder of the examination is unremarkable.

Laboratory studies: WBC 3.8 k/mcL, hemoglobin 13.1 g/dL, platelets 94 k/mcL. AST 82 U/L, ALT 96 U/L, LDH 480 U/L. Creatinine 1.0 mg/dL. Serum sodium 131 mEq/L. Blood cultures are pending.