A 20 year old women has 48 hour history of progressive headache and fever that are associated with nausea, vomiting, epigastric pain. On examination, she appears restless and confused. Temp 38.10, HR 110/min. BP 150/90 mmHg, RR 22/min. reminder of physical examination is unremarkable. Laboratory studies show Hb 9.7 g/dl, MCV 102 fL, WBC 6000/ul, PLT 5000/ul, haptoglobin 10 mg/dl, LDH 600 U/l, and creatinine 1,7 mg/dl. A peripheral blood film shows fragmented RBCs. Which of the following is the most likely diagnosis?