A 43-year-old male presented with fever for 3 days accompanied by headache and general malaise. He visited a hospital on August 9 and was treated for upper respiratory infection without improvement. His temperature continued to rise, and he was hospitalized on day 10 of illness. Physical examination: temperature 40.2°C, somnolence, HR 100 bpm, soft S1, liver palpable 2 cm below the costal margin with soft consistency, spleen palpable 1 cm below the costal margin, mild abdominal distension. Laboratory tests: WBC 4.0×10⁹/L (N 68%, L 32%), ALT 160 U/L, anti-HBc (+), HAV-IgM (-), EKG showed myocardial damage. Widal test results: 'O' 1:80, 'H' 1:160. The most likely diagnosis is: