A 26-year-old male presents with sudden onset of fever, chills, headache, and generalized myalgia for 3 days after harvesting rice. Physical exam: temperature 38.6°C, conjunctival congestion, heart rate 90 bpm, clear lungs. Initially treated as "upper respiratory infection" but symptoms persisted. Laboratory tests: WBC 21.6×10<sup>9</sup>/L (neutrophils 90%), microscopic agglutination test titer 1:400. Diagnosed with leptospirosis. The main clinical manifestations of leptospirosis are: