A 52-year-old male presents with chills and fever for 14 days. Examination: temperature 39.5°C, blood pressure (BP) 75/50 mmHg, ecchymoses on the right upper limb, coarse breath sounds in both lungs, respiratory rate 30/min, liver not palpable below the costal margin, spleen just palpable below the costal margin; hemoglobin (Hb) 112 g/L, white blood cell count (WBC) 18×10<sup>9</sup>/L, prothrombin time (PT) 17 sec (control 12 sec), fibrinogen 1390 mg/L. The most likely diagnosis is: