Leptospirosis Presenting as Sepsis with Pancytopenia in an Outdoor Enthusiast.

We discuss the case of a 39-y-old outdoor enthusiast who developed sepsis with pancytopenia and transaminitis following backcountry camping in the southeastern United States and adventure travel in Costa Rica. Initial evaluation revealed persistent high fevers, leukopenia, thrombocytopenia, and transaminitis, with extensive infectious testing initially negative. Convalescent serology later confirmed leptospirosis. Febrile illness in wilderness travelers and outdoor athletes presents a diagnostic challenge, particularly when initial testing is unrevealing and exposures span both local and tropical environments. Leptospirosis is an underrecognized zoonotic infection that can mimic common viral and bacterial syndromes.