PLE-2388

A 30-year-old male construction worker was admitted due to a fever of 3 days, associated with abdominal pain, diarrhea, myalgia, and headache. On physical examination, there was conjunctival suffusion and calf tenderness. History revealed that he waded in flood water. Vital signs were normal, good urine output, no jaundice, and no signs of meningeal irritation. What is the first-line drug?