A 28-year-old male farmer from Tamil Nadu presents with a 5-day history of high-grade fever, severe headache, myalgia, and conjunctival suffusion without exudate. On day 6, he develops jaundice, acute kidney injury (creatinine 3.2 mg/dL), and pulmonary hemorrhage with hemoptysis. Blood culture on day 2 was positive for a thin, motile, aerobic spirochete. What is the most likely diagnosis?