Review Question - QID 212827

A 60-year-old man presents to the emergency department with a rapid change in his behavior. The patient recently returned from a vacation in rural Mexico and recovered from several episodes of bloody diarrhea. He has had a notable and rapid decline in his memory which started this morning. His personality has also changed, has not been sleeping, and seems generally apathetic. Brief and involuntary muscle twitches have been noted as well. The patient has a past medical history of hypertension and diabetes. His temperature is 99.8°F (37.7°C), blood pressure is 152/98 mmHg, pulse is 97/min, respirations are 14/min, and oxygen saturation is 99% on room air. Physical exam is notable for a confused and apathetic man who is not compliant with the neurological exam. The patient is admitted to the ICU; however, during his hospital course, the patient ultimately dies. Which of the following was most likely to be found in this patient upon initial presentation?